CARDIONET, INC. v. THE SCOTTCARE CORPORATION et al

Filing 231

ORDER THAT UPON CONSIDERATION OF DEFENDANTS' MOTION FOR JUDGMENT ON THE PLEADINGS, OR, IN THE ALTERNATIVE, FOR SUMMARY JUDGMENT (DOC. 211 ) IT IS HEREBY ORDERED THAT THE MOTION IS GRANTED. SIGNED BY HONORABLE PETRESE B. TUCKER ON 07/11/2019. 07/12/2019 ENTERED AND COPIES MAILED AND E-MAILED.(nd, )

IN THE UNITED STATES DISTRICT COURT
FOR THE EASTERN DISTRICT OF PENNSYLVANIA
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CARDIONET, LLC, et al.,
Plaintiffs,
v.
THE SCOTTCARE CORPORATION,
et al.,
Defendants.

CIVIL ACTION
NO. 12-2516

MEMORANDUM
Tucker, J.

July__11___, 2019

In the present motion, Defendants, The ScottCare Corporation and Ambucor Health
Solutions, Inc., ask that the Court grant their Motion for Judgment On The Pleadings Or, In The
Alternative, Summary Judgment (“Motion”) (Doc. 211) with respect to Plaintiffs’ asserted
claims of United States Patent Nos. 7,587,237 (the “ʼ237 Patent”) and 7,941,207 (the “ʼ207
Patent”). For the reasons set forth more fully below, Defendants’ Motion is GRANTED.
I.

FACTUAL AND PROCEDURAL BACKGROUND
Plaintiffs, CardioNet, LLC and Braemar Manufacturing, LLC 1 (collectively, “Plaintiffs”

or “CardioNet”) bring this patent infringement action against Defendants, The ScottCare
Corporation and Ambucor Health Solutions, Inc. (collectively, “Defendants” or “ScottCare”),
alleging that Defendants are infringing five patents originally owned by CardioNet, which

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CardioNet, LLC moved to amend its First Amended Complaint to add Braemar Manufacturing,
LLC as co-party to the present action. Braemar Manufacturing, LLC was added to this suit on
May 10, 2013. During the Markman Hearing, the only parties present were CardioNet, LLC and
ScottCare Corporation.
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CardioNet assigned to Braemer Manufacturing, LLC. 2 Pls.’ Second Am. Compl., Doc. 58. The
patents-in-suit 3—two of which are the subject of the pending motion 4—are directed to multiple
aspects of an electrocardiographic (“ECG”) telemetry device and its software. Pls.’ Second Am.
Compl., Doc. 58. The ECG telemetry device uses a monitor to record and transmit the electrical
activity of the heart over a period of time. Pls.’ Second Am. Compl., Ex. C, Doc. 58. This device
helps medical professionals monitor a patient’s cardiac activity and detect cardiac irregularities.
Pls.’ Second Am. Compl., Ex. C, Doc. 58. The cardiac data recorded by the ECG telemetry
device is transmitted to a remote location where medical technicians review the information.
Pls.’ Second Am. Compl., Ex. C, Doc. 58. This information can then be sent to a medical
professional for further review and diagnosis. Pls.’ Second Am. Compl., Ex. C, Doc. 58.
Plaintiffs allege that Defendants have infringed and are continuing to infringe their
patents by making, using, selling, and/or offering for sale ScottCare’s TeleSentry Mobile Cardiac
Telemetry System, which consists of a device that records and processes a patient’s ECG signal
and a monitoring service whereby personnel at Ambucor evaluate the cardiac data transmitted by
the device. Pls.’ Second Am. Compl., Doc. 58.
A. Overview of CardioNet’s Mobile Cardiac Outpatient Telemetry
(“MCOT™”) Device
CardioNet LLC, a corporation having its principal place of business in Conshohocken,
Pennsylvania, provides continuous, real-time ambulatory “outpatient management solutions for

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On December 31, 2012, CardioNet assigned all rights, title, and interest in the five patents-insuit to Braemar Manufacturing, LLC, and Braemar Manufacturing, LLC granted CardioNet an
exclusive license to make, use, offer to sell, sell, import, license, and exploit the patents-in-suit.
Pls.’ Second Am. Compl. 3, Ex. L, Doc. 58.
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U.S. Patent Nos. 7,212,850 (the “ʼ850 Patent”), 7,907,996 (the “ʼ996 Patent”), 6,569,095 (the
“ʼ095 Patent”), ʼ237 Patent, and the ʼ207 Patent.
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The ʼ237 and ʼ207 Patents.
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monitoring clinical information regarding an individual’s health.” Pls.’ Second Am. Compl. 1,
Doc. 58. CardioNet LLC, through its MCOT™ device, focuses on the diagnosis and monitoring
of cardiac arrhythmias, or heart rhythm disorders. Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 5,
Doc. 224. A cardiac arrhythmia is a disorder of the heart rate or rhythm—i.e. a person’s heart
beats too quickly, too slowly, or with an irregular pattern. Pls.’ Opp’n To Defs.’ Mot. J.
Pleadings 2, Doc. 224. A physician can diagnose an arrhythmia remotely by monitoring a
patient’s heart rhythm. See Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 4–5, Doc. 224. If done
remotely, an ambulatory cardiac monitoring device will record the patient’s heart rate either
intermittently or continuously. See Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 4–5, Doc. 224.
The MCOT™ device enables heartbeat-by-heartbeat ECG monitoring, analysis, and
response, at home or away, 24 hours a day, 7 days a week, 365 days a year. Pls.’ Opp’n To
Defs.’ Mot. J. Pleadings 5, Doc. 224. The MCOT™ device includes a patient-worn sensor
attached to electrodes that capture two-channel ECG data, measuring electrical activity of the
heart and communicating wirelessly with a company-handheld-monitor. Pls.’ Second Am.
Compl., Ex. J, Doc. 58. The monitor analyzes incoming heartbeat-by-heartbeat information from
the sensor on a real-time basis by applying algorithms designed to detect abnormal heart
“events”—i.e. arrhythmias. See Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 4–5, Doc. 224. When the
monitor detects an arrhythmia, “it automatically transmits [ECG] information to [] CardioNet[’s]
monitoring center for analysis and response.” Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 5, Doc.
224.
B. Overview of the ’237 Patent (Patent No. 7,587,237)
The ’237 Patent—entitled “Biological Signal Management”—relates to systems and
techniques for analyzing and handling a patient’s biological signal for medical purposes,

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including notifying cardiac monitoring technicians when an arrhythmia has been detected by the
device. ’237 Patent, Abstract, Ex. A 5. Biological signals are electrical or optical streams that, in
the medical context, include information relating to the physiological state of an organism which
can be used to diagnose and treat disease. ’237 Patent, 1:7–11, Ex. A. The handling of biological
signals includes notifying medical personnel at a remote location when an “event,” such as atrial
fibrillation or atrial flutter (collectively “AF”), is identified. An event is a period in time when
the information content of the cardiac electrical activity is of increased relevance. ’237 Patent,
4:19–23, Ex. A.
The claimed method of the’237 Patent involves receipt of cardiac biological signals
involving events; determining a measure of merit for each identified event; comparing the
measure of merit to a merit criterion; transmitting information of the events meeting the merit
criterion to a remote medical receiver; and discarding information of the events that do not meet
the merit criterion. ’237 Patent, Abstract, Ex. A. The ’237 Patent describes a method of
analyzing biological signals before handling to reduce data clutter and handling costs. ’237
Patent, 2:43–50, Ex. A. By analyzing the biological signal before handling and only transmitting
meritorious events to the monitoring center for review, the volume of data that is handled by the
system is reduced, including the volume of data that is reviewed by medical technicians. ’237
Patent at 2:46–50, Ex. A. “Such reductions in data clutter can be used to quickly provide
physicians with relevant information, decreasing the cost of data review and increasing the
likelihood that diagnosis and/or treatment is appropriately delivered.” ’237 Patent, 2:46–50, Ex.
A.

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Attached hereto as Exhibit A.
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C. Overview of the ’207 Patent (Patent No. 7,941,207)
The ’207 Patent—entitled “Cardiac Monitoring”—relates to “[s]ystems and techniques
for monitoring cardiac activity.” ’207 Patent, Abstract, Ex. B. 6 The systems and techniques
collect information describing variability in heart beats and determine whether that variability is
indicative of AF. Pls.’ Second Am. Compl. Ex. K, Doc. 58. The patented method accomplishes
this by: (1) “determining a beat-to-beat variability in cardiac electrical activity,” (2) “determining
a relevance of the variability to one of atrial fibrillation and atrial flutter,” and (3) “identifying . .
. an atrial fibrillation [] and atrial flutter event based on the determined relevance.” ’207 Patent,
1:49-56, Ex. B.
D. Overview of the Pending Motion
On September 11, 2018, Defendants filed the instant Motion arguing that the ’237 and
’207 Patents are directed to abstract ideas and that the asserted claims do not contain inventive
concepts, thereby rendering the Patents ineligible under 35 U.S.C. § 101 (“§ 101”). Defs.’ Mot.
for J. On The Pleadings, Or In The Alternative Summ. J. 1, Doc. 211. Defendants further allege
that Plaintiffs are collaterally estopped from asserting infringement of claims 1, 2, 8, 9, 10, 21,
22, and 23 of the ’207 Patent because Judge Talwani of the District Court for the District of
Massachusetts (“Massachusetts District Court”) found the ’207 Patent ineligible under § 101.
CardioNet, LLC v. InfoBionic, Inc., 348 F. Supp. 3d 87 (D. Mass. 2018); Defs.’ Reply in Supp.
of Mot. for J. On The Pleadings, Or In The Alternative Summ. J. 2, Doc. 228.
Plaintiffs respond that the ’237 Patent focuses on a specific method, not an abstract idea
and the asserted claims recite an inventive concept for analyzing ECG data. Pls.’ Opp’n To
Defs.’ Mot. J. Pleadings 11–16, Doc. 224. Regarding the ’207 Patent, Plaintiffs claim that

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Attached hereto as Exhibit B.
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collateral estoppel does not apply because the Massachusetts District Court did not adjudicate
identical issues. Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 17, Doc. 224. Plaintiffs further argue
that the ’207 Patent is a specific device rather than an abstract idea and the claims recite
inventive concepts that improve AF diagnosis. Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 21–24,
Doc. 224.
II.

STANDARD OF REVIEW
Under Federal Rule of Civil Procedure 12(c), a party may move for judgment on the

pleadings after the pleadings are closed, as long as the party does so early enough not to delay
the trial. Fed. R. Civ. P. 12(c). Courts in this Circuit construe motions for judgment on the
pleadings that assert failure to state a claim under the same standard as motions to dismiss made
pursuant to Rule 12(b)(6). Katzenmoyer v. City of Reading, 158 F. Supp. 2d 491, 496 (E.D. Pa.
2001). “The only notable difference between these two standards is that the court in a motion on
the pleadings reviews not only the complaint but also the answer and written instruments
attached to the pleadings.” Sprague v. Neil, No. 1:05-CV-1605, 2007 WL 3085604, at *2 (M.D.
Pa. Oct. 19, 2007).
To survive a motion to dismiss under Rule 12(b)(6), “a complaint must contain sufficient
factual matter, accepted as true, to ‘state a claim to relief that is plausible on its face.’” Ashcroft
v. Iqbal, 556 U.S. 662, 678 (2009) (quoting Bell Atlantic Corp. v. Twombly, 550 U.S. 554, 570
(2007)). A complaint is plausible on its face when its factual allegations allow a court to draw a
reasonable inference that a defendant is liable for the harm alleged. Santiago v. Warminster
Twp., 629 F.3d 121, 128 (3d Cir. 2010). A court must accept as true all factual allegations
contained in a complaint and interpret them in the light most favorable to the plaintiff. Argueta v.
U.S. Immigration & Customs Enf’t, 643 F.3d 60, 74 (3d Cir. 2011). “While as a general rule, a

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court ma[]y not consider anything beyond the four corners of the complaint on a motion to
dismiss pursuant to 12(b)(6), the Third Circuit has held that a court may consider certain
narrowly defined types of material without converting the motion to dismiss [to one for summary
judgment pursuant [to] Rule 56].” Nasdaq, Inc. v. IEX Group, Inc., 2019 WL 102408, at *2 (D.
N.J. 2019) (citing In re Rockefeller Ctr. Props. Sec. Litig., 184 F.3d 280, 287 (3d Cir. 1999).
“[D]ocument[s] integral to or explicitly relied upon in the complaint may be considered.” In re
Burlington Coat Factory Sec. Litig., 114 F.3d 1410, 1426 (3d Cir. 1997) (internal quotations
omitted).
III.

DISCUSSION
In its Motion, Defendants argue that the ’237 and ’207 Patents are ineligible under § 101

because they are directed to an abstract idea and the asserted claims do not contain an inventive
concept. Defs.’ Mot. for J. On The Pleadings, Or In The Alternative Summ. J. 2, Doc. 211.
Defendants further argue that Plaintiffs are collaterally estopped from alleging infringement of
the asserted claims of the ’207 Patent. Defs.’ Reply in Supp. of Mot. for J. On The Pleadings, Or
In The Alternative Summ. J. 2, Doc. 228. For the reasons that follow, the Court agrees and,
therefore, Defendants’ Motion is GRANTED.
A. Patent Eligibility Under § 101
A patent may be obtained for “any new and useful process, machine, manufacture, or
composition of matter, or any new and useful improvement thereof.” 35 U.S.C. § 101. “Laws of
nature, natural phenomena, and abstract ideas[, however,] are not patentable.” Ass’n. for
Molecular Pathology v. Myriad Genetics, Inc., 133 S. Ct. 2107, 2116 (2013) (internal brackets
omitted) (quoting Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66, 70 (2012)).
The Supreme Court has established a two-step framework through which courts assess patent

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eligibility under § 101. See Alice Corp. Pty. Ltd. v. CLS Bank Int’l., 134 S. Ct. 2347, 2354–55
(2014).
First, a court must determine whether the claims at issue are directed to a patentineligible concept—i.e. laws of nature, natural phenomena, or abstract ideas. Id. at 2355. Second,
if the claims are directed to a patent-ineligible concept, a court then examines whether “the
additional elements transform the nature of the claim into a patent-eligible application.” Id.
(internal quotations omitted). To transform an abstract idea into a patent-eligible application, the
claims must do “more than simply stat[e] the abstract idea while adding the words ‘apply it.’” Id.
at 2357. Stated otherwise, a court must determine whether the elements of the claim, considered
“both individually and as an ordered combination,” contain an “inventive concept.” Id. at 2355
(internal quotations omitted). The presence of an inventive concept will “‘transform the nature of
the claim’ into a patent-eligible application.” Id. (internal quotations omitted).
B. The ’237 Patent
i. Claims 25 and 37 are Representative of All Asserted Claims of the
’237 Patent
District courts are not required to assess each asserted claim of infringement where a
patent’s claims are substantially similar to the representative claims and linked to the same
abstract idea. See Content Extraction & Transmission LLC v. Wells Fargo Bank, Nat’l Ass’n, 776
F.3d 1343, 1348 (Fed. Cir. 2014) (holding that where all of the claims are directed to the same
abstract idea, “addressing each of the asserted patents . . . [is] unnecessary”); Planet Bingo, LLC
v. VKGS LLC, 576 F. App’x 1005, 1007 (Fed. Cir. 2014) (affirming district court’s finding that
“[t]he system claims recite the same basic process as the method claims, and the dependent
claims recite only slight variations of the independent claims.”). The ’237 Patent asserts four (4)

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independent claims—1, 22, 25, and 37—and six (6) dependent claims—4, 6, 11, 17, 29, and 32.
Claims 25 and 37 are representative of the asserted claims of the ’237 Patent.
The ‘237 patent is generally directed to methods of filtering information into different
groups based on identifying characteristics and transmitting a portion of this information to the
cardiac monitoring center for review by medical technicians. ’237 Patent, Abstract, Ex. A.
Claims 1, 22, 25, and 37 explain how information is classified into groups based on certain
attributes that relate to specific cardiac conditions; given a measure of merit; and then
transmitted or discarded based on a comparison between the measure of merit and merit
criterion. ’237 Patent, 15:10–62; 17:4–32; 17:40–18, 18:59–20–3, Ex. A.
Claims 1 i and 25 ii are substantially similar in that they provide the same procedure,
except that Claim 25 is directed to the software for performing the steps of Claim 1. Compare
’237 Patent, 15:10–62, Ex. A with 17:40–18:17, Ex. A. Likewise, Claim 22 iii mirrors the
procedure of Claim 37, iv except that Claim 37 is directed to the software for performing the steps
of Claim 22. Compare ’237 Patent, 17:4–32, Ex. A with 18:59–20–3, Ex. A. The method
claims—Claims 1 and 22—are no different from the software claims—Claims 25 and 37—in
substance; each are directed to the same abstract idea of collecting, classifying, or otherwise
filtering cardiac data. See Alice, 134 S. Ct. at 2360. The method claims recite the abstract idea of
“monitoring a cardiac biological signal using [ECG] monitoring instrumentation” while the
software claims recite programming instructions “to cause one or more machines to perform
[the] operations for monitoring a cardiac biological signal using [ECG] monitoring
instrumentation.” ’237 Patent, 15:10–62; 17:4–32; 17:40–18, 18:59–20–3, Ex. A. Accordingly,
Claims 25 and 37 accurately represent the asserted independent claims of the ’237 Patent. See
Alice, 134 S. Ct. at 2360.

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The dependent claims—Claims 4, 6, 11, 17, 29, and 32—“recite only slight variations of
the independent claims.” Planet Bingo, 576 F. App’x at 1007. Claims 4, v 6, vi and 17, vii depend
on Claim 1 and Claim 11 viii depends on Claim 9, ix which in turn depends on Claim 1. ’237
Patent, 16:4–57, Ex. A. Claim 29 x depends on Claim 27, xi which, in turn, depends on Claim 25;
and Claim 32 xii depends on Claim 25. ’237 Patent, 18:32–37; 18:44–45, Ex. A. Dependent
Claims 4, 6, 11, 17, 29, and 32 define further particulars of Claims 1 and 25, including: (1) using
the same filtering process over a certain time span, and excluding events occurring outside of
that certain time span; (2) providing that the cardiac biological signal will comprise of a
measurement of electrical potential; (3) providing that the information will have a time stamp;
and (4) providing that the cardiac biological signal will comprise an ECG signal. ’237 Patent,
16:4–57, 18:32–37; 18:44–45, Ex. A. The dependent claims merely provide additional
information relating to Claims 1 and 25 by “recit[ing] only slight variations.” Planet Bingo, 576
F. App’x at 1007. Because Claim 25 is representative of Claim 1, Claim 25 accurately represents
the asserted dependent claims of the ’237 Patent.
Accordingly, Claims 25 and 37 accurately represent the asserted claims—Claims 1, 4, 6,
11, 17, 22, 29, and 32—of the ’237 Patent.
ii. Alice Step One Analysis: Patent-Ineligible Concepts
When determining whether computerized technology is directed to an abstract idea,
courts “ask whether the focus of the claims is on the specific asserted improvement in computer
capabilities . . . or, instead, on a process that qualifies as an ‘abstract idea’ for which computers
are merely invoked as a tool.” Enfish, LLC v. Microsoft Corp., 822 F.3d 1327, 1335–36 (Fed.
Cir. 2016), see also In re TLI Commc’ns LLC Patent Litig., 823 F.3d 607, 612 (Fed. Cir. 2016)
(“[A] relevant inquiry at step one is to ask whether the claims are directed to an improvement to

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computer functionality versus being directed to an abstract idea.”) (internal citation omitted)
(internal quotations omitted). If “the plain focus of the claim is on an improvement to computer
functionality itself, not on economic or other tasks for which a computer is used in its ordinary
capacity,” it is not directed to an abstract idea. Enfish, 822 F.3d at 1336. Conversely, if the
claims “are directed to a[n] abstract idea of organizing information through mathematical
correlations with recitation of only generic gathering and processing activities,” or “recite[] a
purely conventional computer implementation of a mathematical formula,” it is directed to an
abstract idea. Id. at 1338–39. Additionally, “[w]here every aspect of the patented method could
be carried out manually, courts tend to find that the method is too abstract to be patentable.”
SkillSurvey, Inc. v. Checkster, LLC, 178 F. Supp. 3d 247, 256 (E.D. Pa. 2016).
Patent claims that “merely collect, classify, or otherwise filter data” are patent-ineligible
under § 101. Intellectual Ventures I LLC v. Erie Indem. Co., 850 F.3d 1315, 1327 (Fed. Cir.
2017); see also TLI, 823 F.3d at 611 (concluding that the patent was directed to the abstract idea
of classifying and storing digital images in organized manner); Content Extraction, 776 F.3d at
1347 (concluding that the patent was “drawn to the abstract idea of 1) collecting data, 2)
recognizing certain data within the collected data set, and 3) storing that recognized data in a
memory”); Bascom Glob. Internet Servs., Inc. v. AT&T Mobility LLC, 827 F.3d 1341, 1348–49
(Fed. Cir. 2016) (concluding that “content filtering system for filtering content retrieved from an
[i]nternet computer network” was directed to an abstract idea); Cyberfone Sys., LLC v. CNN
Interactive Grp., Inc., 558 F. App’x 988, 992 (Fed. Cir. 2014) (“the well-known concept of
categorical data storage, i.e., the idea of collecting information in classified form, then separating
and transmitting that information according to its classification, is an abstract idea that is not
patent-eligible.”).

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a. The asserted claims of the ’237 Patent are directed to an
abstract idea.
Defendants argue that the asserted claims of the ’237 Patent are “directed to the abstract
idea of organizing human behavior.” Defs.’ Mot. for J. On The Pleadings, Or In The Alternative
Summ. J. 16, Doc. 211. Specifically, Defendants contend that the asserted claims are “analogous
to a medical professional checking a patient’s physiological heart data, looking for changes and
similarities in the data, filtering the data the medical professional deems most valuable, and
storing that data for later use.” Defs.’ Mot. for J. On The Pleadings, Or In The Alternative
Summ. J. 14, Doc. 211.
Plaintiffs counter that the asserted claims of the ’237 Patent are not directed to an abstract
idea because “each claim recites a detailed, computer-implemented method governing the flow
and analysis of information between an ECG monitoring instrumentation . . . and a remote
medical receiver.” Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 11, Doc. 224.
The asserted claims of the ’237 Patent recite systems and techniques for monitoring “a
cardiac biological signal.” ’237 Patent, Abstract, Ex. A. This includes determining a “measure of
merit” for each monitored cardiac event. ’237 Patent, 1:28–30, Ex. A. The measure of merit
encompasses both the severity of the cardiac condition related to the event and the amount of
noise in the information describing the event. ’237 Patent, 1:35–37, Ex. A. The measure of merit
for each event is subsequently compared with a merit criterion. ’237 Patent, 1:56–61, Ex. A.
Events that have measures of merit meeting the merit criterion are transmitted to a remote
medical receiver for review by medical technicians; events that have measures of merit that fail
to meet the merit criterion are discarded. ’237 Patent, 1:56–61, Ex. A.
Representative Claims 25 and 37 do not focus “on an improvement to computer
functionality itself,” rather the asserted claims are directed to the abstract idea of merely
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collecting, classifying, or otherwise filtering data into different groups based on identifying
characteristics and transmitting relevant information for review. ’237 Patent, Abstract, Ex. A.
Courts have found these types of patent claims to be abstract ideas. Intellectual Ventures, 850
F.3d at 1327; Content Extraction, 776 F.3d at 1351; Bascom Glob., 827 F.3d at 1348–49;
Cyberfone Sys., 558 F. App’x at 990–92.
In Content Extraction, the Federal Circuit found the asserted claims invalid as patent
ineligible under § 101. Content Extraction, 776 F.3d at 1351. The claims asserted methods of
“extracting data from hard copy documents using an automated digitizing unit such as a
scanner,” “recognizing specific information from the extracted data,” and “storing that
information in a memory.” Id. at 1344. In conducting step one of its Alice analysis, the Federal
Circuit determined that the claims of the asserted patent were generally directed to “the abstract
idea of 1) collecting data, 2) recognizing certain data within the collected data set, and 3) storing
that recognized data in a memory.” Id. at 1347. The court explained that “[t]he concept of data
collection, recognition, and storage is undisputedly well-known,” and emphasized that “humans
have always performed these functions.” Id. The court rejected Plaintiff’s argument that the
claims were patent eligible because they required hardware to perform functions that humans
cannot—processing and recognizing the stream of bits output by the scanner. Id. Comparing the
asserted claims to “the computer-implemented claims in Alice,” the court concluded that the
claims were “drawn to the basic concept of data recognition and storage,” even though they
recited a scanner. Id.
Like the Plaintiff in Content Extraction, Plaintiffs have failed to show that the focus of
the asserted claims of the ’237 Patent are directed to an improvement in computer functionality,
as opposed to generic gathering and processing activities that can be carried out manually.

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Representative Claims 25 and 37 reflect analysis that medical professionals have performed. As
Plaintiffs explain, “the asserted claims of the ’237 Patent . . . enable accurate, automatic review
of a large volume of cardiac monitoring data that was previously reviewed manually by trained
technicians. The claims save physicians or other trained medical personnel from performing
costly review of less clinically-significant data.” Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 12,
Doc. 224 (emphasis added). The asserted claims of the ’237 Patent are directed to the abstract
idea of collecting, classifying, and selectively transmitting relevant data. Having made this
determination, the Court proceeds to the second step of the Alice analysis.
iii. Alice Step Two Analysis: Inventive Concept
An abstract idea does not, in and of itself, render it patent ineligible. Alice, 134 S. Ct. at
2354. A patent that contains an inventive concept will transform the claimed abstract idea into a
patent-eligible application. Id. at 2357. To constitute an inventive concept, the claimed abstract
idea must be more than “well-understood, routine, conventional activity.” Mayo, 566 U.S. at 79.
“[G]eneric computer implementation” is insufficient to transform an abstract idea into a patenteligible invention. Alice, 134 S. Ct. at 2352, 2357.
a. Use of generic computer technology does not render this
otherwise abstract idea inventive.
Defendants argue that the asserted claims of the ’237 Patent add nothing inventive to the
underlying abstract idea because they “merely automate or otherwise make more efficient,
traditional methods or techniques existing in the medical field.” Defs.’ Mot. for J. On The
Pleadings, Or In The Alternative Summ. J. 19, Doc. 211.
Plaintiffs contend that the asserted claims of the ’237 Patent “do not merely computerize
conventional techniques,” but instead recite an inventive concept by “creat[][ing] a combined
measurement of the severity of adverse cardiac events together with the signal noise level, to
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automatically identify less clinically-significant events.” Pls.’ Opp’n To Defs.’ Mot. J. Pleadings
16, Doc. 224. Plaintiffs further argue that the asserted claims of the ’237 Patent are inventive
under the “machine-or-transformation” test because the claims are “tied to a particular machine
or apparatus, namely [ECG] monitoring instrumentation.” Pls.’ Opp’n To Defs.’ Mot. J.
Pleadings 17, Doc. 224.
In Bascom Glob., the Federal Circuit found that patent claims directed to “filtering
Internet content” were patent-eligible under § 101. Bascom Glob., 827 F.3d at 1355. Although
the Federal Circuit found the asserted claims to be directed to the abstract idea of filtering
content, the court determined that the asserted claims contained an inventive concept that
transformed the abstract idea into patent-eligible subject matter. Id. at 1350–52. In so doing, the
Federal Circuit determined that the asserted claims do not: 1) “merely recite the abstract idea of
filtering content along with the requirement to perform it on the Internet, or to perform it on a set
of generic computer components,” and (ii) “preempt all ways of filtering content on the Internet”
or on generic computer components performing conventional activities. Id. at 1350. The court
focused on the technical aspect of the claimed invention and stated that while “[f]iltering content
on the Internet was already a known concept, [] the patent describes how its particular
arrangement of elements is a technical improvement over prior art . . . filters [that] were either
susceptible to hacking and dependent on local hardware and software, or confined to an
inflexible one size-fits-all scheme.” Id. at 1350. The Federal Circuit stated that “[b]y taking a
prior art filter solution (one-size fits-all filter at the ISP server) and making it more dynamic and
efficient (providing individualized filtering at the ISP server) the claimed invention represents a
software-based invention[ ] that improve[s] the performance of the computer system itself.” Id.
at 1351.

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Unlike the claims in Bascom Glob., representative Claims 25 and 37 add nothing
inventive to the abstract idea of collecting, classifying, and selectively transmitting relevant data.
The claim elements, individually or collectively, recite performing the abstract idea with
conventional technology and fail to provide any specific, inventive technological improvement.
Claims 25 and 37 describe “[a]n article comprising one or more machine-readable storing
instructions operable to cause one or more machines to perform operations for monitoring a
cardiac biological signal using [ECG] instrumentation.” ’237 Patent, 17:40–44; 18:59–63, Ex. A.
Notably, a “machine-readable medium” is described as “any computer program product,
apparatus and/or device . . . used to provide machine instructions and/or data to a programmable
processor” and the term “‘machine-readable signal’ refers to any signal used to provide machine
instructions and/or data to a programmable processor.” ’237 Patent, 14:17–31, Ex. A. The claims
do not provide any specific, inventive technological improvement, but rather provide processing
instructions for use on any type of “machine-readable medium.” The ’237 Patent discloses that a
“vari[ety] of implementations of systems and techniques” can be used to implement the Patent’s
claimed process. ’237 Patent, 14:6–57, 14:32–57, Ex. A. Reciting such conventional computer
components is insufficient to transform an abstract idea into a patent-eligible invention. Alice,
134 S. Ct. at 2352, 2357.
i.

The asserted claims of the ’237 Patent do not satisfy the
machine-or-transformation test.

Under the machine-or-transformation test, a claimed process is patent eligible under §
101 if “it is tied to a particular machine or apparatus” and “the use of a specific machine or
transformation of an article . . . impose meaningful limits on the claim’s scope.” SiRF Tech., Inc.
v. Int’l Trade Com’n, 601 F.3d 1319, 1332 (Fed. Cir. 2010) (internal citation omitted). “In order
for the addition of a machine to impose a meaningful limit on the scope of a claim, it must play a
16

significant part in permitting the claimed method to be performed, rather than function solely as
an obvious mechanism for permitting a solution to be achieved more quickly.” Id. at 1333.
“[S]imply implementing a mathematical principle on a physical machine, namely a computer,
[i]s not a patentable application” of an otherwise abstract idea. Alice, 134 S. Ct. at 2357 (internal
citation omitted).
In SiRF Tech., the Federal Circuit held that certain patents related to global positioning
systems (“GPS”) were patent-eligible under § 101. SiRF Tech., 601 F.3d at 1333. The patent
claims were directed to a method of “estimating a plurality of states associated with a satellite
signal receiver” and “forming a dynamic model relating the plurality of states, the dynamic
model operative to compute position of the satellite signal receiver.” Id. at 1332. In concluding
that the patents satisfied the machine-or-transformation test, the court found that the “GPS
receiver” was held to be a “particular machine” that was “integral to each of the claims at issue.”
Id. The court emphasized that the “methods at issue could not be performed without the use of a
GPS receiver,” and there was no evidence that “the calculations [ ] c[ould] be performed entirely
in the human mind.” Id. at 1332–33. Because the claimed method could not be “performed
without a” GPS receiver, the receiver was indispensable to the patented process. Id.
For the reasons stated above, the ’237 Patent fails under the machine-or-transformation
test. Unlike the claims in SiRF Tech., Plaintiffs’ claims are not tied to any particular machine that
is integral to the claimed systems and techniques for monitoring cardiac biological signals. The
asserted claims merely recite conventional computer components for “permitting a solution to be
achieved more quickly” through a machine-readable medium that can be “any computer program
product, apparatus and/or device.” SiRF Tech., 601 F. 3d at 1333. Because the asserted claims of
the ’237 Patent are not directed to a specific machine, they do not contain an inventive concept

17

sufficient to transform the abstract idea into patent-eligible subject matter. For these reasons, the
’237 Patent is directed to an abstract idea and the asserted claims do not add an inventive
element. Accordingly, the asserted claims of the ’237 Patent are patent-ineligible under § 101.
C. The ’207 Patent
Defendants argue that Plaintiffs are collaterally estopped from alleging infringement of
claims 1, 2, 8, 9, 10, 21, 22, and 23 of the ’207 Patent following the Massachusetts District
Court’s decision in CardioNet, LLC v. InfoBionic, Inc. 348 F. Supp. 3d 87 (D. Mass. 2018);
Defs.’ Reply in Supp. of Mot. for J. On The Pleadings, Or In The Alternative Summ. J. 2, Doc.
228. In that case, in ruling on defendant’s motion to dismiss, Judge Talwani determined that
claims 1, 2, 3, 7, 10, 11, 12, and 22 of the ’207 Patent were ineligible under § 101. InfoBionic,
348 F. Supp. at 89. Judge Talwani concluded that “the ’207 patent is directed to an abstract idea
and the asserted claims do not add [] inventive elements.” Id. at 98.
With respect to unadjudicated claims 8, 9, 21, and 23, Defendants maintain that “they
present identical issues” and are representative of Claim 1, which was previously invalidated in
InfoBionic. Defs.’ Reply in Supp. of Mot. for J. On The Pleadings, Or In The Alternative Summ.
J.6, Doc. 228.
Plaintiffs argue that collateral estoppel does not apply to the asserted claims of the ’207
Patent because the Massachusetts District Court did not adjudicate claims 8, 9, 21, and 23 of the
’207 Patent. Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 17, Doc. 224. Plaintiffs further argue that
“the Massachusetts court based a substantial portion of its opinion on the alleged breadth of []
claims [1, 2, 3, 7, 10, 11, 12, and 22]—a rationale that cannot apply to claims 8, 9, 21, and 23.”
Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 17, Doc. 224. Finally Plaintiffs contend that collateral

18

estoppel should not apply because an appeal is pending. Pls.’ Opp’n To Defs.’ Mot. J. Pleadings
18–19, Doc. 224.
i. Collateral Estoppel
The doctrine of collateral estoppel—also known as issue preclusion—precludes a party
from litigating an issue that has previously been decided in a former judicial proceeding. Scooper
Dooper, Inc. v. Kraftco Corp., 494 F.2d 840, 844 (3d Cir. 1974). In Blonder-Tongue, the
Supreme Court unanimously held that where a patent has been declared invalid in a prior
adjudication, an unrelated defendant in a subsequent action for infringement may assert a
collateral estoppel defense based on the previous judgment. Blonder-Tongue Labs., Inc. v. Univ.
of Ill. Found., 402 U.S. 313, 350 (1971); Kaiser Indus. Corp. v. Jones & Laughlin Steel Corp.,
515 F.2d 964, 976 (3d Cir. 1975). In its ruling, the Supreme Court created “a pragmatic formula
that harmonized considerations of due process and judicial economy. It was aimed at producing
substantial justice while avoiding needlessly repetitious litigation.” Kaiser Indus. Corp., 515
F.2d at 976–77.
To invoke the doctrine of collateral estoppel as a defense, a defendant must establish that:
(1) the identical issue was previously adjudicated; (2) the issue was actually litigated; (3) the
previous determination of the issue was necessary to the decision; and (4) the party being
precluded from relitigating the issue was fully represented in the prior action. Stone v. Johnson,
608 F. App’x 126, 127 (3d Cir. 2015). The Third Circuit has also considered whether the issue
was determined by a final and valid judgment. Jean Alexander Cosmetics, Inc. v. L’Oreal USA,
Inc., 458 F.3d 244, 249 (3d Cir. 2006).

19

ii. Claims 1, 2, 10, and 22
In light of the Supreme Court’s holding in Blonder-Tongue, this Court finds that
Plaintiffs are collaterally estopped from alleging infringement of claims 1, 2, 10, and 22 of the
’207 Patent because Judge Talwani of the Massachusetts District Court ruled that these claims
are patent ineligible under § 101. InfoBionic, 348 F. Supp. 3d at 98. With respect to claims 1, 2,
10, and 22, the only element of collateral estoppel that Plaintiffs dispute is whether the
InfoBionic decision constitutes a final judgment. Thus, the Court’s discussion focuses on this
element.
a. The issue was determined by a final judgment.
There is no bright-line rule regarding what constitutes a “final judgment” for issue
preclusion purposes. Free Speech Coal., Inc. v. AG of the United States, 677 F.3d 519, 541 (3d
Cir. 2012). However, “a prior adjudication of an issue in another action must be sufficiently firm
to be accorded conclusive effect.” Id. (internal quotations omitted). When determining whether a
prior ruling was sufficiently firm for preclusion purposes, courts consider the following factors:
(1) whether the parties were fully heard; (2) whether a reasoned opinion was filed; and (3)
whether that decision could have been, or was, appealed. Id. None of these factors alone are
determinative. Id.
The Court finds that the Massachusetts District Court’s decision—concluding that
Plaintiffs’ asserted claims in the ’207 Patent are patent-ineligible—constitutes a final judgment
for collateral estoppel purposes; the parties were fully heard on the issues, the Massachusetts
District Court issued a well-reasoned opinion, and Plaintiffs had a full and fair opportunity to
litigate their claims.

20

First, Plaintiffs were fully heard regarding claims 1, 2, 10, and 22 of the ’207 Patent.
Plaintiffs were represented by competent counsel before the Massachusetts District Court and
had a full opportunity to brief the issues and present oral argument. Second, the Massachusetts
District Court issued a well-reasoned opinion in support of its decisions. The Massachusetts
District Court conducted its Alice analysis and clearly articulated its basis for concluding that
claims 1, 2, 10, and 22 of the ’207 Patent are patent-ineligible because “Plaintiffs’ asserted
claims are not directed to any improvement in the computer technology itself, but rather seek to
improve cardiac monitoring instead through the abstract idea of measuring the variability of
heartbeats.” InfoBionic, 348 F. Supp. 3d at 98. Third, Plaintiffs have appealed the Massachusetts
District Court’s decision to the Federal Circuit. In re Brown, 951 F.2d 564, 569 (3d Cir. 1991)
(internal citation omitted) (“In determining whether the resolution was sufficiently firm, the
second court should consider whether . . . that decision could have been, or actually was,
appealed.”).
Plaintiffs’ contention that collateral estoppel should not apply because the issues have
been appealed is unpersuasive. Pls.’ Opp’n To Defs.’ Mot. J. Pleadings 18–19, Doc. 224. The
collateral estoppel effect of a prior district court decision is not impacted by the fact that an
appeal has been taken from the decision. See Pharmacia & Upjohn Co. v. Mylan Pharm., Inc.,
170 F.3d 1373, 1380–81 (Fed. Cir. 1999) (“[T]he law is well settled that the pendency of an
appeal has no effect on the finality or binding effect of a trial court’s holding.”); Rice v. Dep’t of
the Treasury, 998 F.2d 997, 999 (Fed. Cir. 1993); SSIH Equip. S.A. v. U.S. Int’l Trade Comm’n,
718 F.2d 365, 370 (Fed. Cir. 1983).

21

The Court is satisfied that the Massachusetts District Court conducted an appropriate
assessment of Plaintiffs’ claims. Accordingly, the Court finds that the Massachusetts District
Court’s order granting defendant’s motion to dismiss constitutes a final judgment.
b. The remaining elements of the collateral estoppel analysis are
satisfied.
Although Plaintiffs’ have not contested the remaining elements of collateral estoppel, the
Court has determined that Defendants have satisfied each of the remaining elements. In addition
to finality, the doctrine of collateral estoppel requires that the issue in the present litigation is
identical to the issue previously adjudicated; the issue to have been actually litigated; the
previous determination of the issue to have been necessary to the decision; and the party being
precluded from relitigating the issue to have been fully represented in the prior action. Johnson,
608 F. App’x at 127.
First, in the prior litigation, the Massachusetts District Court was asked to determine
whether claims 1, 2, 3, 7, 10, 11, 12, and 22 of the ’207 Patent were patent-ineligible under §
101. See InfoBionic, 348 F. Supp. 3d at 89–92. This is precisely the same issue that this Court
has been asked to adjudicate with respect to Claims 1, 2, 10, and 22 of the ’207 Patent. Second,
the Massachusetts District Court’s adjudication came after the parties had a full and fair
opportunity to brief and argue the issues; thus, the issues were actually litigated. Third, the
Massachusetts District Court’s decision granting defendant’s motion to dismiss was premised on
the court’s determination that Claims 1, 2, 3, 7, 10, 11, 12, and 22 were patent-ineligible because
they “are not directed to any improvement in the computer technology itself, but rather seek to
improve cardiac monitoring instead through the abstract idea of measuring the variability of
heartbeats.” InfoBionic, 348 F. Supp. 3d at 98. Therefore, the determination that Claims 1, 2, 10,
and 22 were patent-ineligible was necessary to the Massachusetts District Court’s decision in
22

granting defendant’s motion to dismiss. Fourth, Plaintiffs, against whom collateral estoppel is
asserted in this matter, were the same plaintiffs in the prior litigation. Plaintiffs were represented
before the Massachusetts District Court by competent counsel and had a full opportunity to brief
the issues. Therefore, the Court finds that Plaintiffs were fully represented in the prior action.
For the reasons stated above, the Court finds that Plaintiffs had a full and fair opportunity
to present Claims 1, 2, 3, 7, 10, 11, 12, and 22 of the ’207 Patent in the prior litigation.
Accordingly, Plaintiffs are collaterally estopped from litigating Claims 1, 2, 10, and 22 of the
’207 Patent in the present matter.
iii. Claims 8, 9, 21, and 23
Collateral estoppel is not limited to identical patent claims; it may apply to patent claims
that were not previously adjudicated because “[i]t is the issues litigated, not the specific claims
around which issues were framed, that is determinative.” Westwood Chem., Inc. v. United States,
525 F.2d 1367, 1372 (Ct. Cl. 1975). “If the difference between the unadjudicated patent claims
and adjudicated patent claims do not materially alter the question of invalidity, collateral
estoppel applies.” Ohio Wilson Wood Co. v. Alps South, LLC, 735 F.3d 1333, 1342 (Fed. Cir.
2013). In this case, Plaintiffs contest Defendants’ assertion that the differences between
unadjudicated claims 8, 9, 21, and 23 and adjudicated claims 1, 2, 3, 7, 10, 11, 12 and 22 do not
materially alter the question of validity under § 101.
As discussed in Section I.C., the ’207 Patent discloses devices and techniques for
monitoring cardiac activity, in particular, collecting information describing the variability in
heart beats, and determining whether that information is indicative of an AF event. ’207 Patent,
Abstract, 3:7–9, Ex. B. Claims 8, 9, 21, and 23—like previously adjudicated Claims 1, 2, 3, 7,
10, 11, 12 and 22—involve various aspects concerning the variability in beat-to-beat timing; the

23

relevance of this variability to AF; and the identification of an event when the variability is
identified as relevant.
Claim 1 of the ‘207 Patent, an independent claim, recites:
A device, comprising:
a beat detector to identify a beat-to-beat timing of cardiac
activity;
a ventricular beat detector to identify ventricular beats in the
cardiac activity;
variability determination logic to determine a variability in
the beat-to-beat timing of a collection of beats;
relevance determination logic to identify a relevance of the
variability in the beat-to-beat timing to at least one of
atrial fibrillation and atrial flutter; and
an event generator to generate an event when the variability
in the beat-to-beat timing is identified as relevant to
[] at least one of atrial fibrillation and atrial flutter
in light of the variability in the beat-to-beat timing
caused by ventricular beats identified by the
ventricular beat detector.
’207 Patent, 12:12–27, Ex. B. Claims 2, 3, 7, 10, 11, and 12 depend on Claim 1, and read as
follows:
2. The device of claim 1, wherein the relevance determination logic
is to accommodate variability in the beat-to-beat timing caused by
ventricular beats by weighting ventricular beats as being negatively
indicative of the one of atrial fibrillation and atrial flutter.
3. The device of claim 1, wherein the variability determination logic
is to compare times between R-waves in three successive QRS
complexes to determine the variability in the beat-to-beat timing.
....
7. The device of claim 1, wherein the event generator is to generate
an event by performing operations comprising: collecting data
associated with the collection of beats; and transmitting the data
associated with the collection of beats to a remote receiver.
....
10. The device of claim 1, wherein the relevance determination logic
comprises logic to identify the relevance of the variability using a
non-linear function of a beat-to-beat interval.
24

11. The device of claim 1, wherein the beat detector comprises a
QRS detector.
12. The device of claim 1, further comprising a sensor that includes
two or more body surface electrodes subject to one or more potential
differences related to cardiac activity.
’207 Patent, 12:28–36; 12:52–56; 13:5–13, Ex. B. Claim 22 depends upon unasserted Claim
20 xiii and reads as follows:
22. The article of claim 20, determining the relevance comprises:
identifying a beat of the collection as a ventricular beat, and
weighting the beat as being negatively indicative of
the one of atrial fibrillation and atrial flutter.
’207 Patent, 14:39–43, Ex. B. Applying the Alice framework to the ’207 Patent, Judge Talwani
in InfoBionic answered the first step in the affirmative. In reaching this conclusion, Judge
Talwani stated that:
Review of the ’207 patent shows that the claims add conventional
computer components to the abstract idea that AF can be
distinguished by focusing on the variability of the irregular
heartbeat. The specifications describe systems and techniques with
various methods for monitoring that variability. The patent claims
at issue in this case thus appear to be similarly directed to collecting
and analyzing information to detect particular anomalies, and
notifying the user when the anomaly is detected . . . . The idea of
using a machine to monitor and analyze heart beat variability and
interfering beats so as to alert the user of potential AF events may
well improve the field of cardiac telemetry, but Plaintiffs do not
identify improvements to any particular computerized technology.
Thus, the ’207 patent is directed to an abstract idea.
InfoBionic, 348 F. Supp. 3d at 93 (D. Mass. 2018) (internal quotations omitted).
At the second phase of the analysis, Judge Talwani examined and found no innovation in
the individual steps of the asserted claims. Judge Talwani explained that Claims 1, 2, 3, 7, 10, 11,
12 and 22 do not “impose[] a meaningful limit on the abstract idea of identifying AF by looking
at the variability in time between heartbeats and taking into account ventricular beats.” Id. at 97.
25

Judge Talwani emphasized that “Plaintiffs’ asserted claims are not directed to any improvement
in the computer technology itself, but rather seek to improve cardiac monitoring instead through
the abstract idea of measuring the variability of heartbeats.” Id. at 98. Judge Talwani wrote:
The ‘determination logic’ cited by Plaintiffs is not a limitation set
forth in the ’207 patent. Instead, the ‘determination logic’ is
undefined and unspecified. Claim 1 broadly claims the use of
components with ‘variability determination logic to determine a
variability in the beat-to-beat timing of a collection of beats,’
without specifying any limitations to that logic. ’207 Patent 16 col.
12:17-18 [# 25-1]. In claim 2, the determination logic ‘is to
accommodate variability in the beat-to-beat timing caused by
ventricular beats by weighting ventricular beats as being negatively
indicative of the one of atrial fibrillation and atrial flutter.’ Id. at col.
12:29-32. In claim 3 ‘the variability determination logic is to
compare times between R-waves in three successive QRS
complexes to determine the variability in the beat-to-beat timing.’
Id. at col. 12:33-36. And, in claim 10 ‘the relevance determination
logic comprises logic to identify the relevance of the variability
using a non-linear function of a beat-to-beat interval.’ Id. at 17 col.
13:5-8. The innovation of the ’207 patent may be to use computer
equipment and logic to monitor the variability of beats, but nothing
in these claims places any limitation on that abstract idea.
Id. at 97. While Judge Talwani agreed that Claims 2, 3, 10 and 22 add additional information
relating to the variability or determination logic, she determined that they “provide no
meaningful details on how to implement it, and [,]thus[,] add nothing inventive.” Id.
Judge Talwani’s invalidity analysis regarding Claims 1, 2, 3, 7, 10, 11, 12 and 22 applies
to unadjudicated Claims 8, 9, 21, and 23.
Claims 8
Claim 8 depends on invalidated Claim 1. Claim 8 reads as follows:
8. The device of claim 1, wherein relevance determination logic
comprises weighting logic to:
weight variability at a lower end of physiological values as
being substantially irrelevant to the one of atrial
fibrillation and atrial flutter;
weight variability in a midrange of physiological values as
26

being positively indicative of the one of atrial
fibrillation and atrial flutter; and
weight variability in an upper range of physiological values
as being negatively indicative of the one of atrial
fibrillation and atrial flutter.
’207 Patent, 12:57–67, Ex. B. Claim 1 broadly claims the use of components with “relevance
determination logic to identify a relevance of the variability in the beat-to-beat timing to at least
one of the atrial fibrillation and atrial flutter.” ’207 Patent, 12:19–21, Ex. B. Claim 8 merely adds
additional information relating to relevance determination logic.
In holding in InfoBionic that dependent Claim 2—which is dependent on Claim 1—was
patent-ineligible, Judge Talwani stated that the additional information that “determination logic
is to accommodate variability in the beat-to-beat timing caused by ventricular beats by weighting
ventricular beats as being negatively indicative of the one of atrial fibrillation and atrial flutter,”
’207 Patent, 12:28–32, Ex. B, “provided no meaningful details on how to implement it, and thus
added nothing inventive.” InfoBionic, 348 F. Supp. 3d at 98. That Claim 8 also contains further
information on weighting ventricular beats does not materially detract from Judge Talwani’s
invalidity analysis. Simply classifying weight variabilities as “substantially irrelevant,”
“positively indicative,” or “negatively indicative” of AF based on physiological values does not
provide any information on how to implement determination or weighting logic. Therefore, like
invalidated Claims 2, 10, and 22, Claim 8 provides additional information relating to
determination and/or weighting logic, but is void of any details on how to implement it.
Accordingly, Claim 8 does not materially alter the question of invalidity that Judge Talwani
performed with respect to invalidated Claims 2, 10, and 22.

27

Claim 9
Claim 9, which depends on Claim 8—which in turn depends on invalidated Claim 1—
merely contains the limitation of weighting ventricular beats “as being negatively indicative of
the one of atrial fibrillation and atrial flutter.” ’207 Patent, 13:1–4, Ex. B.
9. The device of claim 8, wherein the weighting logic is also to
weight a beat identified as a ventricular beat as being negatively
indicative of the one of atrial fibrillation and atrial flutter.
’207 Patent, 13:1–4, Ex. B. Claim 9 is not patentably distinct from Claim 2 under the InfoBionic
analysis; the claims recite substantially similar language. Claim 2 recites the device of Claim 1 as
“weighting ventricular beats as being negatively indicative of the one of atrial fibrillation and
atrial flutter.” ’207 Patent, 12:28–36, Ex. B. Claim 9 recites the device of Claim 8—which is the
device of Claim 1—as also weighting a “ventricular beat as being negatively indicative of the
one of atrial fibrillation and atrial flutter.” ’207 Patent, 13:1–4, Ex. B. As articulated above,
Judge Talwani determined that Claim 2 provided no meaningful details for implementing
determination logic. InfoBionic, 348 F. Supp. 3d at 97–98. Claim 9 similarly provides no
meaningful details for implementing determination logic or determining the weighting factor.
Therefore, the further narrowing of Claim 9 does not materially alter the question of invalidity
that Judge Talwani performed with respect to invalidated Claims 2, 10, and 22.
Claim 21
Claim 21, xiv which depends on unasserted Claim 20, is directed to the software for Claim
8. Compare ’207 Patent, 12:57–67, Ex. B with 14:25–38, Ex. B.
21. The article of claim 20, wherein determining the relevance
comprises:
weighting variability at a lower end of physiological values
as being substantially irrelevant to the one of atrial
fibrillation and atrial flutter;
weighting variability in a midrange of physiological values
28

as being positively indicative of the one of atrial
fibrillation and atrial flutter;
weighting variability in an upper range of physiological
values as being negatively indicative of the one of
atrial fibrillation and atrial flutter; and
determining a relevance of the weighted variability to the
one of atrial fibrillation and atrial flutter.
’207 Patent, 14:25–38, Ex. B. That Claim 21 is written in terms of “operations” performed by an
“article comprising one or more machine-readable media storing instructions” and includes
“determining a relevance of the weighted variability to the one of atrial fibrillation and atrial
flutter” does not alter the analysis that the Court conducted for Claim 8. See Alice, 134 S. Ct. at
2360 (stating that “media claims rise or fall with its method claims”).
When confronted with method and system claims that were like one another, the Supreme
Court stated:
[T]he system claims are no different from the method claims in
substance. The method claims recite the abstract idea implemented
on a generic computer; the system claims recite a handful of generic
computer components configured to implement the same idea. This
Court has long “warn[ed] . . . against” interpreting § 101 “in ways
that make patent eligibility ‘depend simply on the draftsman’s art.’”
Holding that the system claims are patent eligible would have
exactly that result.
Alice, 134 S. Ct. at 2360 (internal citations omitted). Here, there is no difference in substance
between Claims 8 and 21. Both claims classify weight variabilities as “substantially irrelevant,”
“positively indicative,” or “negatively indicative” of AF based on physiological values.
Accordingly, because there is no meaningful difference in substance between Claims 8 and 21,
the analysis for Claim 8 applies equally to the analysis for Claim 21. Therefore, like invalidated
Claims 2, 10, and 22, Claim 21 provides additional information relating to determination logic,
but is void of any details on how to implement it. Accordingly, Claim 21 does not materially

29

alter the question of invalidity that Judge Talwani performed with respect to Claims 2, 10, and
22.
Claim 23
Claim 23, xv which depends on unasserted Claim 20, is directed to determining beat-tobeat variability.
23. The article of claim 20, wherein:
determining the beat-to-beat variability comprises
determining a factor reflecting the difference
between a first time between a first heartbeat and a
second heartbeat and a second time between a second
heartbeat and a third heartbeat;
the second heart beat follows immediately after the first
heartbeat; and
the third heartbeat follows immediately after the second
heartbeat.
’207 Patent, 14:44–53, Ex. B. As the ’207 Patent specification explains:
The beat-to-beat variability can be determined in a series of
successive beats, e.g., by determining the variability in an interval
between successive R-waves. The event can be identified by
comparing the relevance of the variability to a first predetermined
amount of relevance. Further, the relevance of the variability in the
event can be compared to a second predetermined amount of
relevance to identify the end of the event. The second predetermined
amount can be lower than the first predetermined amount.
’207 Patent, 2:4–12, Ex. B.
In examining Claim 3, Judge Talwani found that comparing “times between R waves in
three successive QRS complexes” did not explain how to implement variability logic. InfoBionic,
348 F. Supp. 3d at 98. “The time period between successive R-waves can be referred to as the R
to R interval.” ’207 Patent, 4:58–59, Ex. B. Three successive QRS complexes include an R-wave
Rn, R-wave Rn-1, and R-wave Rn-2. ’207 Patent, 4:54–58, Ex. B. The R to R interval between R-

30

wave Rn and R-wave Rn-1 is RR(n, n-1) and the R to R interval between R-wave Rn-1 and R-wave
Rn-2 is RR(n-1, n-2). ’207 Patent, 4:59–62. This can be illustrated as follows:

‘207 Patent, Fig. 2, Ex. B.
Like Claim 3, Claim 23 broadly relates to Claim 1 in determining the variability in beatto-beat timing. Claim 23 is directed to the factor DRR(n) given in Equation 1 of the ’207 Patent.

‘207 Patent, 7:40–45. Equation 1 incorporates the times between successive R-waves—RR(n, n1) and RR(n-1, n-2)—as a function of a ratio of the first R to R interval and an immediately
preceding R to R interval. That Claim 23 determines beat-to-beat variability by “determining a
factor reflecting the difference between a first time between a first heartbeat and a second
heartbeat and a second time between a second heartbeat and a third heartbeat” is no different
than determining beat-to-beat variability by measuring times between R waves in successive

31

QRS complexes. Claims 3 and 23 both provide information describing a variability in R to R
intervals over a series of beats.
Although Claims 3 and 23 recite additional information relating to variability logic, they
do not explain how to implement variability logic. Claim 23 does not provide information on
how to determine a factor “reflecting the difference between a first time between a first heartbeat
and a second heartbeat and a second time between a second heartbeat and a third heartbeat.” ’207
Patent, 14:44–53, Ex. B. Claim 23 merely recites generic information that is expressed as
Equation 1. Equation 1 is merely an algorithm and like Claim 3, does not explain how to
ascertain the R-waves—i.e. RR(n, n-1) and RR(n-1, n-2). Accordingly, Claim 23 does not
materially alter the analysis that Judge Talwani performed with respect to Claim 3. Claim 23
offers no additional inventive aspect to what was disclosed in Claim 1 and 3 regarding beat-tobeat variability.
Because the Court determined that asserted Claims 8, 9, 21, and 23 do not materially
differ from Judge Talwani’s analysis of Claims 1, 2, 10, and 22, the Court’s collateral estoppel
analysis of Claims 1, 2, 10, and 22 applies equally to Claims 8, 9, 21, and 23. Accordingly,
Plaintiffs are collaterally estopped from asserting Claims 8, 9, 21, and 23 of the ’207 Patent.
iv. Alice Step One Analysis: Patent-Ineligible Concepts
Even if collateral estoppel did not apply to Claims 8, 9, 21, and 23, the ’207 Patent is
directed to an abstract idea and the asserted claims do not add an inventive element thereby
rendering it patent-ineligible.
As articulated in Section III.B.ii, when determining whether computerized technology is
directed to an abstract idea, courts “ask whether the focus of the claims is on the specific asserted
improvement in computer capabilities . . . or, instead, on a process that qualifies as an ‘abstract

32

idea’ for which computers are merely invoked as a tool.” Enfish, 822 F.3d at 1335–36, see also
In re TLI Commc’ns LLC Patent Litig. 823 F.3d at 612 (“[A] relevant inquiry at step one is to
ask whether the claims are directed to an improvement to computer functionality versus being
directed to an abstract idea.”) (internal citation omitted) (internal quotations omitted). If “the
plain focus of the claim is on an improvement to computer functionality itself, not on economic
or other tasks for which a computer is used in its ordinary capacity,” it is not directed to an
abstract idea. Enfish, 822 F.3d at 1336. Conversely, if the claims are “directed to a[n] abstract
idea of organizing information through mathematical correlations with recitation of only generic
gathering and processing activities,” or “recite[] a purely conventional computer implementation
of a mathematical formula,” it is directed to an abstract idea. Id. at 1338.
a. The asserted claims of the ’207 Patent are directed to an
abstract idea.
Defendants contend that the ’207 Patent claims “are directed to the abstract idea of
identifying common medical conditions—[AF]—by looking at the variability in time between
heartbeats and taking into account any ventricular beats.” Defs.’ Mot. for J. On The Pleadings,
Or In The Alternative Summ. J. 20, Doc. 211. Defendants argue that because the ’207 Patent
claims to automatically identify AF by looking at the “loss of synchrony between the atria and
the ventricles [] leading to ‘irregular’ heartbeats,” it “improperly attempts to claim automatically
identifying [AF] in the same way doctors have always done.” Defs.’ Mot. for J. On The
Pleadings, Or In The Alternative Summ. J. 20, Doc. 211.
Plaintiffs dispute that the ’207 Patent is directed to an abstract idea and argue instead that
the focus of the claims is on a specific device, rather than an abstract idea. Pls.’ Opp’n To Defs.’
Mot. J. Pleadings 21, Doc. 224. Plaintiffs maintain that “[a] device comprising a beat detector,
ventricular beat detector, heart beat variability determination logic, and an event generator for
33

reporting [AF] does not qualify” under any definition as an abstract idea. Pls.’ Opp’n To Defs.’
Mot. J. Pleadings 21, Doc. 224.
Here, the claims at issue are directed to collecting and analyzing information to detect
and notify a user of an AF event. However, “merely presenting the results of abstract process of
collecting and analyzing information, without more . . . is abstract as an ancillary part of such
collection and analysis.” See FairWarning IP, LLC v. Latric Sys., Inc., 839 F.3d 1089, 1093
(Fed. Cir. 2016). The Federal Circuit has “treated collecting information, including when limited
to particular content (which does not change its character as information), as within the realm of
abstract ideas.” Elec. Power Grp., LLC v. Alstom S.A., 830 F.3d 1350, 1353.
In FairWarning IP, LLC v. Latric Sys., Inc., the asserted patent was directed to ways of
“detect[ing] fraud and misuse by identifying unusual patterns in user access of sensitive data.”
FairWarning IP, 839 F.3d at 1092. The claimed systems and methods “record[ed] audit log data
concerning user access of digitally stored patient health information (PHI),” “analyze[d] it
against a rule, and provide[d] a notification if the analysis detect[ed] misuse.” Id. In finding that
the asserted claims were directed to an abstract concept, the Federal Circuit explained that the
use of an enumerated rule to analyze log data did not make the claims patent-eligible. Id. at 1095.
Although plaintiff purported to accelerate the process of analyzing audit log data, the court found
that this came from the capabilities of a general-purpose computer, not from the patented method
itself. Id. at 1096–97. The court found that the asserted claims were directed “to the broad
concept of monitoring audit log data” and did not “propose a solution or overcome a problem
‘specifically arising in the realm of computer [technology].’” Id. at 1097.
Here, the claims of the ’207 Patent recite conventional computer components for
detecting AF by examining the variability of heartbeats. The particular claims seek to identify

34

AF by: (1) “determining a beat-to-beat variability in cardiac electrical activity,” (2) “determining
a relevance of the variability to one of atrial fibrillation and atrial flutter,” and (3) “identifying . .
. . an atrial fibrillation [] and atrial flutter event based on the determined relevance.” ’207 Patent,
1:49–56, Ex. B. Like the claims in FairWarning, the claims here merely use a device and
software to achieve its intended purpose. The focus of the asserted claims “is not on . . . an
improvement in computers as tools, but on certain independently abstract ideas that use
computers as tools.” Elec. Power Grp., 830 F.3d at 1354. Accordingly, the asserted claims of the
’207 Patent are directed to an abstract idea.
v. Alice Step Two Analysis: Inventive Concept
Since the Court has determined that that the asserted claims of the ’207 Patent are
directed to an abstract idea, the Court will now consider whether “the elements of each claim
both individually, and as an ordered combination . . . transform the nature of the claim into a
patent-eligible application.” Alice, 134 S. Ct. at 2355 (internal citation omitted).
a. The asserted claims of the ’207 Patent do not recite an
inventive concept.
Defendants argue that the asserted claims of the ’207 Patent “add nothing inventive to the
abstract idea of identifying [AF] with conventional technology.” Defs.’ Mot. for J. On The
Pleadings, Or In The Alternative Summ. J. 23, Doc. 211. Defendants maintain that “[t]he
asserted claims do not provide any specific or inventive technological improvement” and “say
nothing about how to program the standard equipment to accomplish the claimed function.”
Defs.’ Mot. for J. On The Pleadings, Or In The Alternative Summ. J. 23, Doc. 211.
Plaintiffs respond that the claims are not generic and conventional. Pls.’ Opp’n To Defs.’
Mot. J. Pleadings 22, Doc. 224. Plaintiffs argue that the ’207 Patent “explains how to put the

35

claimed components to a new use to improve cardiac monitoring technology.” Pls.’ Opp’n To
Defs.’ Mot. J. Pleadings 22, Doc. 224.
Dependent Claims 8, 9, 21, and 23 add nothing inventive to the abstract idea that AF can
be determined by examining the variability of heartbeats by collecting and analyzing information
to detect and notify a user of an AF event. The claim elements, individually or collectively, recite
performing the abstract idea with conventional technology and fail to provide any specific,
inventive technological improvement. See Intellectual Ventures I LLC v. Symantec Corp., 838
F.3d 1307, 1315 (Fed. Cir. 2016) (finding no inventive concept where the claimed method of
filtering emails for computer viruses and spam did not “improve the functioning of the computer
itself,” but rather “used generic computers to perform generic computer functions.”).
Claims 8, 9, and 21 relate to relevance determination logic. As discussed in Section
III.C.iii., Claims 8, 9, and 21 do not impose any meaningful limitation on determination logic.
These claims provide no details for determining relevance. Claim 8 merely classifies weight
variabilities as “substantially irrelevant,” “positively indicative,” or “negatively indicative” of
AF based on physiological values. Claim 9 simply contains the limitation of weighting
ventricular beats “as being negatively indicative of the one of atrial fibrillation and atrial flutter.”
And Claim 21 is directed to the software for Claim 8. Claim 21 is written in terms of
“operations” performed by an “article comprising one or more machine-readable media storing
instructions” and includes “determining a relevance of the weighted variability to the one of
atrial fibrillation and atrial flutter.” Individually, or collectively, none of these claims contain
information regarding how to implement “weighting logic” to determine relevance.
Claim 23 relates to beat-to-beat variability. As discussed in Section III.C.iii., Claim 23
provides additional information relating to variability logic, but does not impose any meaningful

36

limitation. Claim 23 does not provide information on how to determine a factor “reflecting the
difference between a first time between a first heartbeat and a second heartbeat and a second
time between a second heartbeat and a third heartbeat.” ’207 Patent, 14:44–53, Ex. B. Although
Claim 23 is related to the factor DRR(n) given in Equation 1 7 of the ’207 Patent, this does not
transform the asserted claims into patent-eligible subject matter. Alice, 134 S. Ct. at 2357
(“simply implementing a mathematical principle on a physical machine, namely a computer, [i]s
not a patentable application” of an otherwise abstract idea.) (internal citation omitted).
In Gottschalk v. Benson, the Supreme Court determined that an algorithm implemented
on “a general-purpose digital computer” was an abstract idea that did not contain an inventive
concept because the process could be “carried out in existing computers long in use.” 409 U.S.
63, 67 (1972). The Court “held that simply implementing a mathematical principle on a physical
machine, namely a computer, was not a patentable application of that principle.” Mayo, 566 U.S.
at 84–85 (citing Benson, 409 U.S. at 64). The Court explained that a patent cannot cover all
possible uses of a mathematical procedure or equation within a computer.
Here, the ’207 Patent specification explains that a “vari[ety] of implementations of”
conventional computer hardware/software can be used to implement the claimed functions of the
’207 Patent. See ’207 Patent, 9:22–23, Ex. B; 11:5–9, Ex. B. Specifically, a patient’s ventricular
beats and the beat-to-beat timing can be determined using “components that can be purchased
off-the-shelf such as a QRS detector and the Mortara VERITAS analysis Algorithm or the ELI
250YM Electrocardiograph.” Defs.’ Mot. for J. On The Pleadings, Or In The Alternative Summ.

7

37

J. 8, Doc. 211. Equation 1 of the ’207 Patent “can be carried out in existing computers” and
therefore, like the algorithm in Gottschalk, does not transform the asserted claims into patenteligible subject matter. Equation 1 is not limited to any particular machinery or equipment and
instead can be used on any type of conventional computer hardware/software. Further, the
“machine-readable medium” referenced in Claim 21 is described as “any computer program
product, apparatus and/or device . . . used to provide machine instructions and/or data to a
programmable processor.” ’207 Patent, 11:17–30, Ex. B. The ’207 Patent does not claim any
new or improved approach in computer technology. As Defendants maintain the ’207 Patent
“describes performing the steps in functional terms, using conventional, pre-existing medical and
computer technology.” Defs.’ Mot. for J. On The Pleadings, Or In The Alternative Summ. J. 8,
Doc. 211.
Plaintiffs’ asserted claims individually, or collectively, are not directed to an
improvement in computer technology, but seek to improve cardiac monitoring through the
abstract idea of measuring the variability of heartbeats by collecting and analyzing data.
Accordingly, the ’207 Patent is directed to an abstract idea and the asserted claims do not add an
inventive element.
IV.

CONCLUSION
For the reasons stated above, the Court finds that the ’237 and ’207 Patents are directed

to abstract ideas and the asserted claims do not add an inventive element thereby rendering the
patents ineligible under § 101. The Court also finds that Plaintiffs are collaterally estopped from
asserting infringement of Claims 1, 2, 8, 9,10, 21, 22, and 23 of the ’207 Patent. Accordingly,
Defendants’ Motion is GRANTED. An order consistent with this memorandum follows.

38

Claim 1 –A method of monitoring a cardiac biological signal using electrocardiographic
monitoring instrumentation, comprising:
receiving, at the electrocardiographic monitoring instrumentation, the cardiac biological
signal that includes information describing events, wherein events comprise periods
in time when an information content of the cardiac biological signal is of increased
relevance to a particular purpose and the events are demarcated by periods of time
that are not of increased relevance to the particular purpose;
at the electrocardiographic monitoring instrumentation, classifying the events into two or
more categories based on cardiac conditions indicated by the information
describing each event;
at the electrocardiographic monitoring instrumentation, determining a measure of merit
of the information describing each event, wherein the measure of merit embodies a
severity of the cardiac condition associated with the event and an amount of noise
in the information describing the event;
comparing, at the electrocardiographic monitoring instrumentation, the measure of merit
of information describing each event with a first merit criterion;
transmitting, for medical purposes, information describing a first proper subset of the
events in a first of the categories that have merits meeting the first merit criterion
from the electrocardiographic monitoring instrumentation to a remote medical
receiver, wherein the remote medical receiver is not located at the same site at the
electrocardiographic monitoring instrumentation;
at the electrocardiographic monitoring instrumentation, discarding information describing
a second proper subset of the events in the first of the categories that have measures
of merit that fail to meet the first merit criterion;
comparing, at the electrocardiographic monitoring instrumentation, the measure of merit
of information describing each event with a second merit criterion;
transmitting, for medical purposes, information describing a third proper subset of the
events in a second of the categories that have measures of merit meeting the second
merit criterion from the electrocardiographic monitoring instrumentation to the
remote medical receiver, wherein the second category differs from the first category
and the second merit criterion differs from the first merit criterion; and
at the electrocardiographic monitoring instrumentation, discarding information describing
a fourth proper subset of the events in the second of the categories that have
measures of merit that fail to meet the second merit criterion.
’237 Patent, 15:10–62, Ex. A.
i

Claim 25 –An article comprising one or more machine-readable media storing instructions
operable to cause one or more machines to perform operations for monitoring a cardiac biological
signal using electrocardiographic monitoring instrumentation, the operations comprising:
receiving the cardiac biological signal that includes information describing events,
wherein events comprise periods in time when an information content of the cardiac
biological signal is of increased relevance to a particular purpose and the events are
demarcated by periods of time that are not of increased relevance to the particular
purpose;
classifying the events into two or more categories based on cardiac conditions indicated
by the information describing each event;
ii

39

determining a measure of merit of the information describing each event, wherein the
measure of merit embodies a severity of the cardiac condition associated with the
event and [] an amount of noise in the information describing the event;
comparing the measure of merit of information describing each event with a first merit
criterion;
transmitting, for medical purposes, information describing a first proper subset of the
events in a first of the categories that have merits meeting the first merit criterion
to a remote medical receiver, wherein the remote medical receiver is not located at
the same site at the electrocardiographic monitoring instrumentation;
discarding information describing a second proper subset of the events in the first of the
categories that have measures of merit that fail to meet the first merit criterion;
comparing the measure of merit of information describing each event with a second merit
criterion;
transmitting, for medical purposes, information describing a third proper subset of the
events in a second of the categories that have measures of merit meeting the second
merit criterion to the remote medical receiver, wherein the second category differs
from the first category and the second merit criterion differs from the first merit
criterion; and
discarding information describing a fourth proper subset of the events in the second of the
categories that have measures of merit that fail to meet the second merit criterion.
’237 Patent, 17:40–18:17, Ex. A.
Claim 22 –A method of monitoring a cardiac biological signal using electrocardiographic
monitoring instrumentation, comprising:
receiving a cardiac biological signal that includes information describing events at the
electrocardiographic monitoring instrumentation, wherein events comprise periods
in time when an information content of the cardiac biological signal is of increased
relevance to a particular purpose and the events are demarcated by periods of time
that are not of increased relevance to the particular purpose;
determining, at the electrocardiographic monitoring instrumentation, a measure of merit
of information describing each event, wherein the measure of merit embodies both
the severity of the cardiac condition indicated by the information describing the
event and an amount of noise in the information describing the event;
comparing, at the electrocardiographic monitoring instrumentation, the measure of merit
of information describing each event with a merit criterion;
transmitting, for medical purposes, information describing a first proper subset of the
events that have measures of merit meeting the merit criterion from the
electrocardiographic monitoring instrumentation to a remote medical receiver; and
discarding information describing a second proper subset of the events that have
measures of merit that fail to meet the merit criterion at the electrocardiographic
monitoring instrumentation.
’237 Patent, 17:4–32, Ex. A.
iii

iv

Claim 37 –An article comprising one or more machine-readable media storing instructions
operable to cause one or more machines to perform operations for monitoring a cardiac biological
signal using electrocardiographic monitoring instrumentation, the operations comprising:
receiving a cardiac biological signal that includes information describing events, wherein
40

events comprise periods in time when an information content of the cardiac
biological signal is of increased relevance to a particular purpose and the events are
demarcated by periods of time that are not of increased relevance to the particular
purpose;
determining a measure of merit of information describing each event, wherein the
measure of merit embodies both the severity of the cardiac condition indicated by
the information describing the event and an amount of noise in the information
describing the event;
comparing the measure of merit of information describing each event with a merit
criterion;
transmitting, for medical purposes, information describing a first proper subset of the
events that have measures of merit meeting the merit criterion to a remote medical
receiver; and
discarding information describing a second proper subset of the events that have
measures of merit that fail to meet the merit criterion.
’237 Patent, 18:59–20:3, Ex. A.
v

Claim 4 –The method of claim 1, wherein:
the first proper subset of the events comprises events that occur within a certain time span
and excludes events occurring outside the certain time span.
’237 Patent, 16:4–7, Ex. A.
vi

Claim 6 –The method of claim 1, wherein receiving the cardiac biological signal comprises
receiving a measurement of electrical potential. ’237 Patent, 16:12–14, Ex. A.
vii

Claim 17 –The method of claim 1, wherein the cardiac biological signal comprises an
electrocardiogram signal. ’237 Patent, 16:56–57, Ex. A.
viii

Claim 11–The method of claim 9, wherein associating the information describing each event in
the first proper subset with the information describing the time span comprises generating a data
structure having a time stamp associated with the information describing the event. ’237 Patent,
16:34–38, Ex. A.
ix

Claim 9 –The method of claim 1, further comprising associating information describing each
event in the first proper subset with information describing a time span in which the event occurred.
’237 Patent, 16:23–26, Ex. A.

x

Claim 29 –The article of claim 27, wherein associating the information describing each event in
the first proper subset with the information describing the time span comprises generating a data
structure having a time stamp associated with the information describing the event. ’237 Patent,
18:32–37, Ex. A.
xi

Claim 27 –The article of claim 25, wherein the operations further comprise associating
information describing each event in the first proper Subset with information describing a time
span in which the event occurred. ’237 Patent, 18:21–24, Ex. A.
41

xii

Claim 32 –The article of claim 25, wherein the cardiac biological signal comprises an
electrocardiogram signal. ’237 Patent, 18:43–44, Ex. A.
xiii

Claim 20 –An article comprising one or more machine-readable media storing instructions
operable to cause one or more machines to perform operations, the operations comprising:
determining a beat-to-beat variability in cardiac electrical activity;
determining a relevance of the variability over a collection of beats to one of atrial
fibrillation and atrial flutter using a non-linear function of a beat-to-beat interval;
and
identifying one of an atrial fibrillation event and an atrial flutter event based on the
determined relevance, the event being a period in time when the information
content of the cardiac electrical activity is of increased relevance to the one of atrial
fibrillation and atrial flutter.
’207 Patent, 14:12–24, Ex. B.
xiv

Claim 21 –The article of claim 20, wherein determining the relevance comprises:
weighting variability at a lower end of physiological values as being substantially
irrelevant to the one of atrial fibrillation and atrial flutter;
weighting variability in a midrange of physiological values as being positively indicative
of the one of atrial fibrillation and atrial flutter;
weighting variability in an upper range of physiological values as being negatively
indicative of the one of atrial fibrillation and atrial flutter; and
determining a relevance of the weighted variability to the one of atrial fibrillation and
atrial flutter.
’207 Patent, 14:25–38, Ex. B.
xv

Claim 23 – The article of claim 20, wherein:
determining the beat-to-beat variability comprises deter mining a factor reflecting the
difference between a first time between a first heartbeat and a second heartbeat and
a second time between a second heartbeat and a third heartbeat;
the second heart beat follows immediately after the first heartbeat; and
the third heartbeat follows immediately after the second heartbeat.
’207 Patent, 14:44–53, Ex. B.

42

Exhibit A

US007587237B2

(12) United States Patent

(10) Patent No.:

Korzinov et al.

US 7.587,237 B2

(45) Date of Patent:

(54) BIOLOGICAL SIGNAL MANAGEMENT

5,365,935 A

75

Sep. 8, 2009

1 1/1994 Righter et al.

5,383,909 A

1/1995 Keimel

(75) Inventors: Ley Korzinov, San Diego, CA (US);

5,413,594 A

5, 1995 Williams

5,421,342 A

6/1995 Mortara

(73) Assignee: Cardionet, Inc., San Diego, CA (US)

5.487,754 A

1/1996 Snell et al.

5.490,515 A

2/1996 Mortara

5,513,645 A

5/1996 Jacobson et al.

Eric Baumann, San Diego, CA (US)
-

(*) Notice:

Subject to any disclaimer, the term of this

patent is extended or adjusted under 35
U.S.C. 154(b) by 393 days.

21) A1. No
(21) Appl. No.: 1 Of770,702
9

(22) Filed:

(Continued)

Feb. 2, 2004

(65)

FOREIGN PATENT DOCUMENTS

Prior Publication Data

US 2005/O171448A1

WO

WO8901803

3, 1989

Aug. 4, 2005

(51) Int. Cl.
A6 IB5/04

(2006.01)

(Continued)

(52) U.S. Cl. ...................................................... 6OOASO9
(58) Field of Classification Search ................... 607/18:
6OO/509

See application file for complete search history.
(56)

References Cited
4,223,678
4,295,474
4,336,810
4,622,979
4,625,730
4,630,204
4,920,489
4,938,228
4,951,681
5,012,814
5,086,778
5,113,869
D326,716
5, 191,891
5,197.479
5,226.425
5,312,446
5,355,892

Multi-lead Arrhythmia Analysis.” Proceedings of IEEE Computers in

Cardiology Conference 2002, pp. 85-88.

Primary Examiner Mark W Bockelman

U.S. PATENT DOCUMENTS
9, 1980
10, 1981
* 6, 1982
11, 1986
12, 1986
12, 1986
4, 1990
7, 1990
8, 1990
5, 1991
2, 1992
5, 1992
6, 1992
3, 1993
3, 1993
7, 1993
5, 1994
10, 1994

OTHER PUBLICATIONS
Wang, J.Y. “A New Method for Evaluating ECG Signal Quality for

Assistant Examiner Eric D Bertram

Langer et al.
Fischell
Anderson et al. ........... 600,515
Katchis et al.
Fountain et al.
Mortara
Hubelbank et al.

Righter et al.
Mortara
Mills et al.
Mueller et al.

Nappholz et al.
Mortara

Righter

(74) Attorney, Agent, or Firm Fish & Richardson P.C.
(57)

ABSTRACT

Systems and techniques for managing biological signals. In
one implementation, a method includes receiving a cardiac
biological signal that includes information describing events,
determining a merit of each event based on one or more of a
severity of a cardiac condition associated with the event and a
quality of the event, and handling a Subset of the events that
meet a merit criterion. The subset can be handled for medical
purposes.

Hubelbank et al.

Righter
Holschbach et al.
Saltzstein et al.

39 Claims, 7 Drawing Sheets

Moderate Bradycarcia: <60 bpm for 15 seconds
Severe Bradycardia. K4bpm for 15 seconds

OO

US 7.587,237 B2
Page 2
U.S. PATENT DOCUMENTS
5,518,001
5,522,850
5,524,631
5,546,950

A
A
A *
A

5,549,654 A
5,581.369 A

5,634,468 A

5,678,562 A
5,704,351 A
5,730,143 A

5, 1996
6, 1996
6/1996
8, 1996

6,664,893 B1

6,697,655 B2

Snell
Yomtov et al.
Zahorian et al. ............ 600,511
Schoeckert et al.

6,778,859
6,823,210
6,925,331
7,047,065

8, 1996 Powell

7,058.442 B1

12/1996 Righter et al.
1/1998 Mortara et al.
3/1998 Schwarzberg

2/2004 Sueppel et al.

8/2004
11/2004
8/2005
5/2006

Graindorge
Eberle et al.
Samuelson et al.
Kalgren et al.

6/2006 Platt et al.

7,117,037 B2

10/2006 Hiebert et al.

7.286,872 B2

6, 1997 Platt et al.

10/1997 Sellers

B2
B2
B2
B2

12/2003 Eveland et al.

10/2007 Kramer et al.

2002/0067256 Al

6/2002 Kail, IV

2002/0107553 A1*
2002/0137994 A1*

8, 2002 Hill et al. ...................... 607/18
9, 2002 Baker et al. ................. 600/310

5,732,708 A *

3/1998 Nau et al. ................... 600,523

2003/0028442 A1

2/2003 Wagstaffetal.

5,827, 196 A

10/1998 Yeo et al.

2003/006948.6 A1

4/2003 Sueppel et al.
4, 2003 Mortara

5,876.349 A

3/1999 Wang et al.

2003, OO69487 A1

5,959,529 A

9/1999 Kail, IV

2003/0122677 A1

7/2003 Kail, IV

5.966,692 A

10/1999 Langer et al.

2003/0172940 A1

9/2003 Rogers et al.

5,967,994. A

10/1999 Wang

2004/0085186 A1

5/2004 Eveland et al.

6,102,856 A

8, 2000 Groffet al.

6,119,035 A
6,225,901 B1

9/2000 Wang
5/2001 Kail, IV
9/2001 Lugo

6,287.252 B1
6,317,626 B1
6,526.314 B1
-4 W

1 1/2001 Warman
2/2003 Eberle et al.

FOREIGN PATENT DOCUMENTS
WO
WO

WO O2/O852OO A2
WO O2/O852O1 A1

10, 2002
10, 2002

WO

WO O2/O86792 A2

10, 2002

3/2003 Hiebert et al.

WO

WO O2/O86793 A2

10, 2002

WO

WO 02/086835 A1

10, 2002

6,564,077 B2

5/2003 Mortara

WO

WO O2/O86837 A1

10, 2002

6.569,095 B2

5/2003 Eggers

WOO3,O77752 A1

9, 2003

6,604,115 B1

8/2003 Gary, Jr. et al.

6,535,763 B1

6,589,187 B1 * 7/2003 Dirnberger et al. .......... 600,508

* cited by examiner

U.S. Patent

Sep. 8, 2009

US 7.587,237 B2

Sheet 1 of 7

100

RECEIVER

F.G. 1

Signal

205

Attribute

200

210

Time

FG. 2

FIG. 3

U.S. Patent

Sep. 8, 2009

US 7.587,237 B2

Sheet 2 of 7

Moderate Bradycarcia: <60 bpm for 15 seconds
Severe Bradycardia: <40 bpm for 15 seconds

210

FIG. 4

510

515

520

525

FIG.S

U.S. Patent

Sep. 8, 2009

605

6 O

US 7.587,237 B2

Sheet 3 of 7

620

6 1. 5

625

Signal
Attribute

FIG. 6
700
705

eVent X

time stamp

710

FG, 7
800

EVENT

CATEGORY

category a

805
810
815

ALLOCATION
820

time stamp 2

ALLOCATION

event 3
time stamp 3

825

FG. 8

U.S. Patent

Sep. 8, 2009

Sheet 4 of 7

US 7.587,237 B2

900

RECEIVE BIOLOGICAL SIGNAL

905

IDENTIFY AND CLASSIFY EVENT IN
RECEIVED SIGNAL

910

915

DETERMINE MEASURE OF THE MERIT OF
IDENTIFIED EVENT
DISCARD
IDENTIFIED
EVENT

925

920

MERIT OF IDENTIFIED EVENT
D

MERIT OF LEAST MERITORIOUS,
CURRENTLY ALLOCATED
EVENT

Y
930

DISCARD LEAST MERITORIOUS, CURRENTLY
ALLOCATED EVENT
ALLOCATE IDENTIFIED EVENT TO SPAN

935

940

END OF TIMESPAN

Y
945

HANDLE ALLOCATED EVENT(S)

FG. 9

U.S. Patent

Sep. 8, 2009

Sheet 5 of 7

US 7.587,237 B2

000

1005

DETERMINE SEVERITY OF AN EVENT

DETERMINE QUALITY OF THE EVENT
DETERMINE MEASURE OF THE MERIT OF

1010

1015

EVENT BASED ON SEVERITY AND QUALITY

FIG. 10

U.S. Patent

Sep. 8, 2009

Sheet 6 of 7

US 7.587,237 B2
1200

COLLECTION TITLE

1205

COLLECTION METADATA

1210

EVENT CATEGORY 1

1220

it
EVENT CATEGORY 2

1225

EVENT CATEGORY N

1230

1215

F.G. 12
100

RECEIVER
700-

1100

.

C

NC

1
O

110

FIG. 13

U.S. Patent

Sep. 8, 2009

Sheet 7 Of 7

US 7.587,237 B2

100

1200

FIG. 14

F.G. 15

US 7,587,237 B2
1.
BOLOGICAL SIGNAL MANAGEMENT

2
span. For example, the time span can be predetermined. The

BACKGROUND

subset of events can be transmitted to a remote medical
receiver.

This disclosure relates to the management of biological
signals.
Biological signals are electrical or optical streams that
include information describing or otherwise relating to the
state of a biological system. In the medical context, biological
signals generally include information relating to the physi
ological state of an organism. Such information can be used to
diagnose and treat disease states of the organism and can be
gathered using any of a number of different techniques.
Examples of Such techniques include electrical potential
measurements (e.g., electrocardiography (ECG's), elec
tromyography, and electroencephalography), blood and other
body fluid analyte measurements (e.g., pulse oximetry, blood
glucose concentration, blood pH and other ion concentra
tions), and mechanical measurements (e.g., blood pressure
measurements, heart Sound transduction, height and weight
measurements).

In another aspect, a method includes receiving a biological
signal, identifying an event in the biological signal, determin
ing a merit of the event for the certain purpose, comparing the
merit of the event with a second merit of a second event to
10

15

the event can also be determined. The merit of the event can

SUMMARY

The biological signal management systems and techniques
described here may include various combinations of the fol
lowing features.
In one aspect, a method includes receiving a cardiac bio
logical signal that includes an event relevant to a medical
purpose, determining a merit of the event for the medical
purpose, associating the event with a time span in which the
event occurred if the events merit is among a certain number
of the most meritorious events that occurred in the time span,
and handling the association of the time span and the event.
The merit of the event can be determined by determining
the severity and the quality of the event. The quality of the
event can be determined by determining the noise in the event.
An event can be received after the event has been separated
from another portion of the cardiac biological signal. The
event can also be identified within the received cardiac bio

25

30

35

40

of these events. The event can be identified based on a fre
45

the event within the certain number of the most meritorious

events of the category. The number of the most meritorious
events can be predetermined. The association can be handled
by generating a data structure having a time stamp associated
with the event or by transmitting the association to a remote
receiver. The event can have a greater relevance to a medical
diagnostic purpose than an average relevance of the biologi
cal signal.
In another aspect, a method includes receiving a cardiac
biological signal that includes information describing events,
determining a merit of each event based on one or more of a
severity of a cardiac condition associated with the event and a
quality of the event, and handling a Subset of the events that

50

55

60

meet a merit criterion.

The subset can be handled for medical purposes. The merit
criterion can be based on merits of other events. The merit of

each event can be determined based on both the severity and
the quality of the event. The subset can be the events that have
merits among a certain number of the most meritorious and
the subset can be the events that occur within a certain time

be compared with the second merit of the second event of the
same category. The association of the episode and the time
span can be associated with a collection of associations of
episodes and time spans. The resulting collection of associa
tions of episodes and time spans can be transmitted to the
remote receiver.

logical signal. The event can be one or more of an asystole
event, a tachycardia event, a bradycardia event, and an atrial
fibrillation/flutter event based on identifying characteristics
quency of heartbeats.
A category of the event can be determined. The event can
be associated with the time span when the event merit places

identify a more meritorious event, creating an episode
describing the more meritorious event, associating the epi
sode with a time span in which the events occurred, and
transmitting the association of the episode and the time span
to a remote receiver. The event can have a greater relevance
for a certain purpose than an average relevance of the biologi
cal signal.
The episode can be associated with the time span by cre
ating a data structure including the episode and a time stamp
indicating when the event occurred. The episode can be cre
ated by redacting the more meritorious event. A category of

65

These biological signal management systems and tech
niques may provide one or more of the following advantages.
For example, the management of biological signals can facili
tate a coherent approach to organization and presentation of
the information contained in the biological signals. Such
management must address various objectives that often
oppose one another. For example, the Volume of data often
should be reduced to minimize data handling costs. At the
same, relevant information should not be lost. These objec
tives are of importance in the medical context, where data
review may be carried out by a physician or other trained
personnel and hence may prove costly. On the other hand,
discarding medically relevant information may hinder or
even prevent appropriate diagnosis and/or treatment.
The described biological management systems and tech
niques can address these and other objectives by increasing
the average relevance of data that is handled. Such reductions
in data clutter can be used to quickly provide physicians with
relevant information, decreasing the cost of data review and
increasing the likelihood that diagnosis and/or treatment is
appropriately delivered.
Another set of opposing objectives relates to the timing of
data handling. In many data handling systems, continuous
handling of data is simply too costly. On the other hand, batch
handling that only occurs occasionally may resultin improper
delays. These objectives are also of importance in the medical
context, where continuous data handling may be unnecessary
or too costly, but delayed handling may endanger patients.
The described biological management systems and tech
niques can address these and other objectives by selecting the
timing of data handling to accommodate both the realities of
data handling and the need to ensure patient safety. For
example, the timing of handling can be selected to ensure
timeliness in any prophylactic or diagnostic efforts without
requiring continuous processes.
The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other

US 7,587,237 B2
3
features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
5

FIG. 1 shows a system in which a biological signal is
monitored for medical purposes.
FIG. 2 shows an example biological signal.
FIG. 3 shows a series of events in the biological signal of
FIG 2.
FIG. 4 illustrates how certain characteristics can be used to

10

identify events.
FIGS. 5 and 6 show the biological signal of FIG. 2 divided
into a collection of time spans.
FIGS. 7 and 8 show data structures that associate one or

15

more events with a time span.
FIG.9 shows a process in which events are associated with
a time span.
FIG. 10 shows a process for determining a measure of the

330,335,340,345 identified. Events 305,310,315,320,325,

merit for an event.

FIG.11 shows a data structure that can result from handling
of events associated with time spans.
FIG. 12 shows a data assembly that can result from han
dling of events associated with time spans.
FIGS. 13 and 14 illustrate the handling of events associated
with time spans by transmission to a receiver.
FIG. 15 shows a system in which events associated with
time spans are handled by transmission to a receiver.
Like reference symbols in the various drawings indicate

25

like elements.

30

DETAILED DESCRIPTION

FIG. 1 shows a system 100 in which a biological signal
derived from an individual is monitored for medical purposes.
System 100 includes an individual 105, instrumentation 110.
a signal path 115, and a receiver 120. Individual 105 can be a
patient or a healthy individual for whom monitoring of one or
more biological signals is deemed to be appropriate. Instru
mentation 110 can include one or more sensing, calibration,
signal processing, control, data storage, and transmission ele
ments suitable for generating and processing the biological
signal, as well as relaying all or a portion of the biological
signal over path 115. Path 115 can be any suitable medium for
data transmission, including wired and wireless media Suit
able for carrying optical and/or electrical signals. The
receiver 120 can include a receiver element for receiving the
transmitted signal, as well as various data processing and
storage elements for extracting and storing the information
carried by the transmission regarding the state of individual
105. The receiver 120 can be a medical system in that receiver
120 presents information to medical personnel or to a medical
expert system for analysis. The receiver 120 either can reside
remotely from instrumentation 110 in that receiver 120 is not

4
located at the same site (e.g., at the same hospital, nursing
home, or other medical care facility) as instrumentation 110
or the receiver 120 can reside within the same general area or
vicinity as instrumentation 110 (e.g., within the same room,
building, or health care facility).
FIG. 2 shows an example of a biological signal 200. The
biological signal 200 is a time variant signal in that an
attribute 205 of biological signal 200 changes with time 210.
Attribute 205 of biological signal 200 may continuously
change with time and may never reach a steady state value as
activity level, metabolic rate, or other factors vary over the
course of days, weeks, or even longer periods of time.
Although attribute 205 of biological signal 200 may
change continuously, all of the changes may not have the
same relevance to a particular purpose for which the biologi
cal signal 200 is monitored. FIG. 3 shows the biological
signal 200 having a series of events 305,310,315,320, 325,

35

40

45

50

330,335,340,345 generally are periods in time 210 when the
information content of biological signal 200 is deemed to be
of increased relevance to a particular purpose for which bio
logical signal 200 is monitored. Events 305,310,315, 320,
325,330,335,340,345 need not be of equal or predetermined
duration. For example, event 335 is shorter than event 320 and
the duration of these and other events can depend on the
nature of the increased relevance to the particular purpose for
which biological signal 200 is monitored.
The increased relevance of events 305,310,315,320, 325,

330, 335, 340, 345 can be determined using a number of
approaches. For example, events 305, 310, 315, 320, 325,
330, 335, 340, 345 can represent responses to known or
controlled stresses on an organism.
Events 305,310,315,320,325, 330,335,340,345 also can

be identified based on characteristics of biological signal 200
and classified into categories based on the identifying char
acteristics. Tables 1 and 2 lists example categories of cardiac
events and characteristics that can be used to identify the
events. The characteristics identified in Tables 1 and 2 can be

used to identify events during cardiac monitoring using elec
trocardiography.
FIG. 4 illustrates an example of how the characteristics
identified in Table 1 can be used to identify cardiac events. In
this example, the attribute 205 of biological signal 200 that
changes with time 210 (shown in seconds) is heart rate
(shown in beats perminute (bpm)). In the illustrated example,
the predetermined heart rate for identifying Moderate Brady
cardia is 60 bpm and the predetermined duration is 40 sec
onds. The predetermined heart rate for identifying Severe
Bradycardia is 40 bpm and the predetermined duration is 15
seconds.

In FIG. 4, heart rate attribute 205 drops below 60 bpm at
time 405, where it remains until
TABLE 1.

Event Category Identifying Characteristic(s)

Duration

VFIB

Ventricular fibrillation

NA

Long Pausef

No QRS detected for a predetermined duration.

e.g., 3 to 6

Four or more V-beats in row and heart rate more

4 V-beats

Asystole
WTACH

Seconds

than a predetermined value (e.g., 100 to 200 bpm).
Not associated with a VFIB event

Patient
initiated event

Patient indicates event is occurring

Patient selected

US 7,587,237 B2
5
TABLE 1-continued
Event Category Identifying Characteristic(s)
Severe

Tachycardia

Duration

Heart rate over a predetermined time (e.g., 10 to 120 e.g., 10 to 120
Seconds) is greater than a predetermined value (e.g., Seconds
161 to 220 bpm)
Not associated with a VTACH or a VFIB event

Severe

Bradycardia
Atrial
Fibrillation
Flutter with

Heart rate over a predetermined time (e.g., 10 to 120 e.g., 10 to 120
Seconds) is less than a predetermined value (e.g., 30 Seconds
to 39 bpm)
Not associated with an asystole or pause event
Heart rate greater than or equal to a predetermined e.g., 10 to 120
Seconds
value (e.g., 100 to 220 bpm)
Associated with an Atrial Fibrillation Flutter onset

High HR

event

Pause

No QRS complex for a predetermined duration (e.g., e.g., 2 seconds
2 seconds to duration of Long Pause Asystole event) to duration of
Long Pause
Asystole event
rregular rhythm
e.g., 30 QRS
Not associated with a VTACH and VFIB event
complexes

Atrial
Fibrillation
Flutter onset
Moderate

Bradycardia

Moderate

Tachycardia

Heart rate for a predetermined duration (e.g., 10 to e.g., 10 to 120
120 seconds) is less than a predetermined value and Seconds
greater than predetermined value in a severe
bradycardia event (e.g., severe bradycardia value to
60 bpm)
Not associated with an asystole, a pause, or a severe
bradycardia event
Heart rate for a predetermined duration (e.g., 10 to e.g., 10 to 120
20 seconds) is greater than a predetermined value Seconds
and less than predetermined value in a severe
achycardia event (e.g., 100 bpm to the severe
achycardia value)
Not associated with a VTACH, a VFIB, or a severe
achycardia event

time 410, 40 seconds later. The period between time 405 and Bradycardia event. At time 430, heart rate attribute 205 again
time 410 can be identified as a Moderate Bradycardia event. 35 drops below 40 bpm, where it remains until time 435, five
In contrast, at time 415, heart rate attribute 205 drops below seconds later. The duration of the period between time 430
40 bpm where it remains until time 420, ten seconds later. and time 435 is too short to be identified as a Severe Brady
Heart rate attribute 205 also reaches a minimum of 35 bpm at cardia event.
FIGS. 5 and 6 show that time 215 can be divided into a
a time 425. Despite reaching this minimum, the duration of
the period between time 415 and time 420 (i.e., 10 seconds) is 40 collection of time spans 505, 510,515,520, 525, 605, 610,
too short to be identified as a Severe
615, 620,625. Spans 505, 510,515,520,525,605, 610, 615,
TABLE 2
EVENT
CATEGORY

IDENTIFYING
CHARACTERISTICS

EXAMPLE
IDENTIFYING
THRESHOLD

TACHYCARDIA
Sustained heart rate (e.g., heart rate for 10 to 1 - Sustained heart rate exceeds
- Severe Tachycardia 120 seconds) exceeds a heart rate threshold a High Heart Rate (HHR)
2 - Moderate
threshold of 190 bpm
Tachycardia
2 - Sustained heart rate exceeds
a Low Heart Rate (LHR)
threshold of 140 bpm
ATRIAL
Loss of synchrony between the atria and the 1 - Heart rate exceeds a Atrial
FIBRILLATION
ventricles (shown, e.g., by variability in
Fibrillation High Heart Rate
- Atrial Fibrillation? beat-to-beat period)
(AFHHR) threshold of 130 bpm
2 - No heart rate threshold
Flutter with High
HR
2 - Atrial Fibrillation

PAUSE
- Asystole
2 - Pause

No QRS detected for a specified threshold
duration

1 - No QRS for a high threshold
of 4 seconds

2 - No QRS for a low threshold
of 2 seconds
1 - Sustained heart rate is below

BRADYCARDIA
Sustained heart rate (e.g., heart rate for 10 to
- Severe Bradycardia 120 seconds) is below a specified threshold a Low Heart Rate (LHR)
threshold of 35 bpm.
Bradycardia
2 - Sustained heart rate is below
a High Heart Rate (HHR)
threshold of 40 bpm.

2 - Moderate

US 7,587,237 B2
7
620, 625 can have equal durations (such as spans 505, 510,
515,520, 525) or spans can be of variable durations (such as
spans 605, 610, 615, 620, 625). In general, the duration of
spans 505, 510, 515, 520, 525, 605, 610, 615, 620, 625 is
proportional to the duration of the events sought to be iden
tified. The duration of spans 505, 510,515,520, 525, 605,

8
description of a memory location that includes such informa
tion. Each instance of data structure 800 can be specific to a
single span.
Allocation information fields 815, 820, 825 each describe
5

category described in event category information field 805
and when the event occurred in a time span described in span

610, 615, 620,625 can be selected based on consideration of

two or more factors, such as the number of events likely to
occur in each span and the need to handle events for a par
ticular purpose for which biological signal 200 is monitored.
In particular, if spans 505,510,515,520,525, 605, 610, 615,
620, 625 are too short, then spans 505, 510,515,520, 525,
605, 610, 615, 620,625 may lack an event. On the other hand,
if spans 505, 510,515,520, 525, 605, 610, 615, 620,625 are
too long, then the delay in handling events may be too large.
Such a delay may be particularly harmful in the medical
context, where an excessive delay may hinder prophylactic or
diagnostic efforts. In the context of cardiac monitoring, a span

a certain event that is allocated to data structure 800. An event
can be allocated to data structure 800 when the event is of a
identification information field 810. Such allocations thus

10

associate the event with the described category and time span.
Allocation information fields 815, 820, 825 can describe an

event by including an event field and a time stamp field, Such
as fields 705, 710 of data structure 700 (FIG. 7).
Data structure 800 can include one or more allocation
15

information fields. Single allocation fields decrease the size
of data structure 800 and may facilitate handling. Multiple
allocation fields increase the number of events associated

with the span identified by span identification information
field 810 and may provide more complete information when

duration of between one half and four hours, such as between

one and three hours or approximately two hours, is effective

data structure 800 is handled.

to address such considerations.

FIG.9 shows a process 900 in which events are associated
with a time span. Events can be associated with a time span by

The duration of spans 505, 510,515,520, 525, 605, 610,
615, 620, 625 can also accommodate physiological rhythms
of a biological system. For example, in cardiac monitoring,
longer spans may be appropriate at night or periods of
decreased activity and shorter spans may be appropriate dur
ing the day or periods of increased activity. The duration of
spans 505, 510,515,520, 525, 605, 610, 615, 620,625 can
also be adjusted based on an attribute of biological signal 200.
For example, in cardiac monitoring, the duration of spans
505, 510,515,520, 525, 605, 610, 615, 620,625 can include
a fixed number of beats rather than a fixed time period.

allocation to a data structure such as data structures 700, 800.
25

30

FIGS. 7 and 8 show data structures 700, 800 that associate

one or more sample events with a span. Data structures 700,
800 can be used together or separately as alternative
approaches to associating events with a span. Data structure
700 includes an event field 705 and a time stamp field 710.
Event field 705 includes data describing a portion of a bio
logical signal that has been identified as an event. Event field
705 can include raw data drawn from the biological signal or
event field 705 can include an episode of an event to describe
the event. An episode is a collection of information that Sum
marizes the relevance of the event to the purpose for which the
event is monitored. For example, an episode can be a redacted
portion of an event (e.g., the first three minutes worth of the
event). Time stamp field 710 includes data describing the time

35

40

measure of the merit of identified events at 915. A measure of
45

when the event described in event field 705 occurred. Time

stamp field 710 can thus associate the event with a span by
identifying a time that falls within the time span.
pairs but other data structures (including, for example,
records, files, lists, and other data structures) that associate
similar information can be used. Data structure 800 includes

55

information field 810, and allocation information fields 815,

820,825. Event category information field 805 describes one
or more event categories that are allocable to data structure
800. An event category can be described by name, by an
associated identification number or other token, or by a
pointer or other description of a memory location that
includes Such information. Span identification information
field 810 describes the time span from which events of a
category identified in event category information field 805 are
allocable to data structure 800. The time span can be
described directly using, e.g., a start and stop time stamp, or
the time span can be described indirectly by a pointer or other

the merit of an event is a valuation of an event when applied
to a particular purpose. For example, when the biological
signal is monitored for diagnostic medical purposes, the mea
Sure of the merit of an event can describe the diagnostic value
of the information content of the event. The measure of the

50

Data structure 800 is shown as a table of attribute-value

an event category information field 805, span identification

The process 900 can be performed by one or more data
processing devices that perform data processing activities.
The activities of process 900 can be performed in accordance
with the logic of a set of machine-readable instructions, a
hardware assembly, or a combination of these and/or other
instructions. The device performing process 900 can be
deployed at any of a number of different positions in a system
in which a biological signal is monitored. For example, in
system 100 (FIG. 1), the device performing process 900 can
be deployed at instrumentation 110 or at receiver 120.
The device performing process 900 receives the biological
signal at 905. The biological signal can be received in raw
form or after signal processing. The biological signal can be
received in digital or analog format. The receiving device can
identify and classify one or more events in the biological
signal at 910. Events can be identified and classified based on
one or more attributes of the biological signal. Such as the
identifying characteristics described in Table 1.
The device performing process 900 can also determine a

merit of an event can be based on a number of factors, includ

ing whether or not the event is representative of the biological
signal or of other events of the same category in the biological
signal, the quality (e.g., noise or signal dropout) associated
with the event, and even the category of the event itself.
The device performing process 900 can determine if the
measure of the merit of an event identified at 910 is greater
than the measure of the merit of the least meritorious event of

the same category currently associated with the time span that
includes the identified event at decision 920. The least meri
60

torious event of the same category can be associated with the
time span in a data structure such as data structures 700, 800
(FIGS. 7 and 8). The determination can be made by compar
ing the measure of the merit of the identified event with the

65

of the same category. If the identified event is not as merito
rious, the device performing process 900 can discard the

measure of the merit of the associated, least meritorious event
identified event at 925.

US 7,587,237 B2
On the other hand, if the identified event is more meritori
ous than the associated, least meritorious event of the same

10
attention, whereas event grade '2' can indicate a chronic or
other medical condition that does not require immediate

category, then the device performing process 900 can discard

medical attention.

Another approach to determining the severity of an event
involves comparing characteristics of the biological signal
during the event with threshold values relating to various
physiological conditions associated with the events. For
example, for a tachycardia event as described in Table 2, the
severity of a tachycardia event can be determined using Equa

the latter at 930 and associate the more meritorious event

identified at 910 with the time span at 935. For example, the
device performing process 900 can allocate the more merito
rious event identified at 910 to the appropriate of fields 715,
805,810 in data structures 700, 800 (FIGS. 7 and 8).
The device performing process 900 can determine if the
end of a time span in the biological signal has been reached at
decision 940. If the end of the span has not been reached, the
process 900 returns to 910 to identify and classify any addi
tional event(s) in the biological signal. If the end of the span
has been reached, the process proceeds to handle the allocated

10

15

events at 945. The events can be handled alone or in associa

tion with other information, including duration and classifi
cation information, prior and Subsequent events of the same
or different categories, and additional information retrieved
from other biological signals.

Grade

VFIB

HeartRate

WTACH
Patient initiated

25

1
1
1

Asystole

30

event

Severe

1

Tachycardia
Severe

1

Bradycardia
Atrial
Fibrillation
Flutter with

2
35

High HR
Pause
Atrial
Fibrillation
Flutter onset
Moderate

2
2

Equation 4

The device performing process 1000 can also determine
the quality of the event at 1010. The quality of the event is a
measure of the likelihood that the event is suited to the pur
pose for which the biological signal is monitored. One factor
that can impact quality is the amount or type of noise in the
biological signal during the event. For example, when the
biological signal is a cardiac signal monitored for diagnostic
medical purposes, noise can be determined using approaches
such as those described in Wang, J. Y. “A New Method for
Evaluating ECG Signal Quality for Multi-lead Arrhythmia
Analysis.' appearing in Proceedings of IEEE Computers in
Cardiology Conference 2002, pp. 85-88 and U.S. Pat. No.
5,967,994 to Jyh-Yun Wang, the contents of both of which are
incorporated herein by reference. Quality can be graded on a
discrete scale or on a continuous scale.

2

40

TABLE 4

Bradycardia
Moderate

Equation 3

Pause Severity=(Pause Duration-Low Threshold),
(High Threshold-Low Threshold)

1

Long Pausef

Equation 2

AFIB Severity=Heart Rate/Atrial Fibrillation High

Event

Category

Equation 1

Similarly, the severity of a Bradycardia event, and Atrial
Fibrillation Event, and a Pause event can be determined using
the appropriate of Equations 2-4:
Brady Severity=(High Heart Rate-Low Heart Rate),
(High Heart Rate-Low Heart Rate)

TABLE 3
Event

tion 1:
Tachy Severity=(Heart Rate-Low Heart Rate)/(High
Heart Rate-Low Heart Rate)

2

Severity

Tachycardia

Noise

Quality

Low
45

FIG. 10 shows a process 1000 for determining a measure of
the merit of an event. A data processing device can perform
the process 1000 in isolation or as part of a larger process. For
example, the process 1000 can be performed within process
900 at 915 (FIG.9). The device performing process 1000 can
determine the severity of an event at 1005. The severity of an
event is a measure of the gravity of the event to the purpose for
which the biological signal is monitored. For example, when
the biological signal is monitored for diagnostic medical pur
poses, the severity of an event can be indicative of the indi
vidual’s physical discomfort or hardship associated with a
diagnosis that can be made using the event. Severity can be
graded on a discrete scale or on a continuous scale. Table 3
shows example discrete grades of the severity of various
cardiac events when cardiac monitoring is performed for
prophylactic and diagnostic purposes. In Table 3, events are
graded on a two point scale, with an event grade of “1”
indicating that the event is more severe and an event grade of
“2 indicating that the event is less severe (e.g., a moderately
sever event). For example, event grade “1” can indicate an
acute medical condition that requires immediate medical

High

Lowest

Low
Low

Medium
Low

Low
Low

Medium

55

60

65

Low

Medium

Medium

Medium
50

High

Medium

Low

High

High
High
High

High
Medium
Low

Low
High
High

The device performing process 1000 can determine the
measure of the merit of an event based at least in part on the
severity and quality of the event at 1015. The measure of the
merit can be graded on a discrete scale or on a continuous
scale. The measure of the merit can be determined using any
of a number of different approaches. Table 4 includes
examples of various discrete merit grades (lowest, low,
medium, and high) that can be assigned to an event when an
event is determined to have the corresponding severity and
quality.
The handling of allocated events, such as those allocated
during a process such as process 900, can involve any of a
number of different activities. For example, event handling
can include notifying medical personnel about the event.
Such notification can be performed in response to the identi

US 7,587,237 B2
11

12
categories. For example, each data structure 1220, 1225, 1230

fication of an event associated with an acute medical condi

tion, such as those events graded level “1” in Table 3. Event
handling can also include the assembly of more complex data

can include a data structure such as data structure 1100. Since

structures, the transmission of allocated events to, for

different categories selected for high information content,
data collection 1200 can include a relatively large amount of
information regarding a biological signal but yet retain a high
density of information content.
FIGS. 13 and 14 illustrate another way that events associ
ated with time spans are handled, namely by transmission to
a receiver in a system such as receiver 120 in system 100. In
particular, as shown in FIG. 13, data can be gathered and

example, a receiver such as receiver 120 (FIG. 1), or the
storage of allocated events (for example, in anticipation of
assembly into more complex data structures or transmission).
Such data structure assembly, transmission, and storage can
be performed with events associated with medical conditions
that do not require immediate medical attention, such as those
graded level “2” in Table 3.

each data structure 1220, 1225, 1230 can include events from
5

10

FIG. 11 shows a data structure 1100 that can result from

handling of events associated with time spans. The events and
time spans can be associated by repeated performance of
process 900 by a data processing device. Data structure 1100
includes a data assembly 1105, a series of associated events
1110, and a series of discarded events 1115. Data assembly
1105 includes a collection of time span records, including
time span records 1120, 1125, and 1130. Time span records
1120, 1125, 1130 can include information identifying the
duration of an associated time span. For example, time span
record 1120 can include information identifying that span
record 1120 lasts from 12 AM to 6 AM, whereas time span
record 1130 can include information identifying that span
record 1130 lasts from 4 PM to 6 PM. Time span records
1120, 1125, 1130 can include information identifying one or
more categories of events associated with time span records
1120, 1125, 1130, as well as a severity of any associated
category of events. For example, data structure 1100 can be
devoted to events of a certain severity, such as level 2 events

events can be allocated at instrumentation 110 to form one or

more of assemblies of data such as data structures 700, 800,
15

immediate transmission.

25

30

records of one or more categories, including event records
1135, 1140, 1145, 1150. Associated events 1110 can be allo
35

40

45

50

55

collection title 1205, data collection metadata 1210, and a

a telephone network. Private network portion 1535 provides
for private or virtually private data communication from

collection metadata 1210 can include information about the
60

result from associating events of different categories with
time spans and can include one or more events of different

server 1540 to receiver 120. Server 1540 can interface for data

communication with both portions 1530, 1535. For example,
server 1540 can communicate directly with receiver 120
using the peer-to-peer protocol (PPP).

Series of data structures 1215 includes data structures

1220, 1225, 1230. Each data structure 1220, 1225, 1230 can

The instructions can describe how to identify and/or handle
events in accordance with one or more of the techniques
described herein. In one implementation, monitor module
1510 also includes an input/output device for interaction with
a user (such as an event trigger input with which a user can
manually trigger the start of an event.
Signal path 115 can include one or both of a wired data link
1515 and a wireless data link 1520 coupled to a data network
1525 to place instrumentation 110 in data communication
with receiver 120. Wired data link 1515 includes a public
network portion 1530 and a private or virtual private network
portion 1535 bridged by a server 1540. Public network por
tion 1530 provides for data communication between instru
mentation 110 and server 1540 over a wired data link such as

series of data structures 1215. Data collection title 1205 can

include information identifying data collection 1200. Data
data in collection 1200, such as the subject of the biological
signal, parameters regarding the instrument used to generate
the biological signal, and date and location information
regarding the data generation process.

electrodes, as well as a two channel ECG signal recorder and
a wireless and/or wired data output. Sensor module 1505 can
also include a clip for attaching sensor module to a belt, a
neckpiece, or other item worn by individual 105. Monitor
module 1510 includes a data input that is adapted to receive
data output from sensor module 1505 as well as one or more
wireless and/or wired data outputs for data communication
over signal path 115. Monitor module 1510 also includes a
data processing device that performs data processing activi
ties in accordance with the logic of a set of machine-readable
instructions. The instructions can be realized in digital elec
tronic circuitry, integrated circuitry, specially designed
ASICs (application specific integrated circuits), computer
hardware, firmware, software, and/or combinations thereof.

record 1130.
Discarded events 1115 includes a collection of event

records of one or more categories. Discarded events 1115 are
not associated with the time spans in data assembly 1105 or
with any of allocated events 1110.
FIG. 12 shows another data assembly, namely a data col
lection 1200, that can result from handling of events associ
ated with time spans. Data collection 1200 includes a data

FIG. 15 shows one implementation of system 100 in which
a biological signal derived from an individual is monitored for
medical purposes. System 100 includes individual 105,
instrumentation 110, signal path 115, and receiver 120.
Instrumentation 110 can be adapted for electrocardio
graphic monitoring of individual 105. Instrumentation 110
can include a sensor module 1505 and a monitor module
1510. Sensor module 1505 can include three ECG leads with

as discussed above.
Associated events 1110 includes a collection of event

cated to the time spans in data assembly 1105 by allocation to
an appropriate time span record. Event records can include
data describing the event (such as raw data from the relevant
portion of biological signal 200). Associated events 1110 can
be allocated to the appropriate time span records through a
series of pointers 1155. For example, event records 1135,
1140, 1145 are allocated to time span record 1120 through a
first pointer 1155, whereas event record 1150 is associated
with time span record 1125 through a second pointer 1155. A
time span record need not have an associated event record.
For example, no event record is associated with time span
record 1130. This lack can reflect that no appropriate event
was identified within the time span associated with time span

1100 and data collection 1200. In response to a trigger, data
assemblies can be relayed over path 115 to receiver 120,
where they are received as shown in FIG. 14. Example trig
gers include the passage of a predetermined period of time,
user input indicating that transmission is appropriate, or the
identification of an event of sufficient severity to warrant

Wireless data link 1545 can include one or more wireless
65

receivers and transmitters 1550 such as a WiFi receiver, a

cellular phone relay station, and/or other cellular telephone
infrastructure to place instrumentation 110 in data communi

US 7,587,237 B2
14
needed, a message requesting that the individual seek care
can be returned to individual 105 over data link 115. In urgent
care situations, third parties such as medical personnel can be
directed to individual 105, either by receiver 120 or by instru

13
cation with data network 1525. In turn, data network 1525
communicates with receiver 120.

Receiver 120 includes a receiver server 1555, a data storage
device 1560, a call router 1565, a communications server

1570, and one or more application servers 1575 that are all in

5

mentation 110.

10

Various implementations of the systems and techniques
described here can be realized in digital electronic circuitry,
integrated circuitry, specially designed ASICs (application
specific integrated circuits), computer hardware, firmware,
software, and/or combinations thereof. These various imple
mentations can include one or more computer programs that
are executable and/or interpretable on a programmable sys
tem including at least one programmable processor, which
may be special or general purpose, coupled to receive data

data communication with one another over one or more data

links 1580. Receiver server 1555 is a data processing device
that receives and transmits communications over signal path
115 and relays incoming communications to data storage
device 1560 and call router 1565 in accordance with the logic
of a set of machine-readable instructions. Data storage device
1560 is a device adaptable for the storage of information. Data
storage device 1560 can be a volatile and/or non-volatile
memory that records information electrically, mechanically,
magnetically, and/or optically (such as a disk drive). Call
router 1565 is a data processing device that, in accordance
with the logic of a set of machine-readable instructions, iden
tifies the content of an incoming communication and directs
the communication to one or more appropriate application

15

servers 1575 based on that content. Communications server

1570 is a data processing device that relays communications
between call router 1565 and one or more application servers
1575 over an external network. Application servers 1575 are
data processing devices that interact with a user or operate in
isolation to provide one or more monitoring services in accor
dance with the logic of a set of machine-readable instructions.
Data links 1580 can be part of a local area and/or private
network or part of a wide area and/or public network.
In operation, sensor module 1505 can sense, amplify, and
record electrical signals relating to the activity of the heart.
Sensor module 1505 can also relay all or a portion of those
signals to monitor module 1510 where they can be managed.
For example, monitor module 1510 can manage the signals in
accordance with one or more of processes 900 and 1000
(FIGS. 9-10). As part of the management, monitor module
1510 can transmit the signals to receiver 120. The signals can
be transmitted in association with a time span. For example,
the signals can be transmitted in one or more of data structures
700, 800, 1100, 1200 (FIGS. 7-8 and 11-12).
The transmitted signals pass along data link 115 over one

As used herein, the term “machine-readable medium” refers

25

30

35

40

45

device 1560 can be stored in one or more of data structures

700, 800, 1100, 1200 (FIGS. 7-8 and 11-12).
The incoming signals relayed to call router 1565 are
directed to one or more appropriate application servers 1575
based on the content of the signals. For example, when the
signal relates to a certain category of cardiac event, the signal
can be directed to a certain application server 1575 that is
accessible to a cardiologist having expertise with that certain
category of event. As another example, when the signal origi
nates with an individual who is under the care of a particular
physician, the signal can be directed to a certain application
server 1575 that is accessible to that physician. As yet another
example, when the signal relates to a certain category of
cardiac event, the signal can be directed to a certain applica
tion server 1575 that accesses an expert system or other set of
instructions for diagnosing and/or treating that category of
event. When appropriate, a signal can be routed to commu
nications server 1570 which in turn relays the signal to the
appropriate application server 1575 over an external network.
Communications can also be relayed from receiver 120
back to individual 105 or to other individuals. For example,
when a physician or expert System identifies that care is

to any computer program product, apparatus and/or device
(e.g., magnetic discs, optical disks, memory, Programmable
Logic Devices (PLDs)) used to provide machine instructions
and/or data to a programmable processor, including a
machine-readable medium that receives machine instructions

or more of wired data link 1515 and wireless data link 1520 to

receiver 120. At receiver 120, the signals are received by
server 1555 which causes at least a portion of the incoming
signals to be stored on data storage device 1560 and relayed to
call router 1565. The incoming signals stored on data storage

and instructions from, and to transmit data and instructions to,

a storage system, at least one input device, and at least one
output device.
These computer programs (also known as programs, soft
ware, Software applications or code) may include machine
instructions for a programmable processor, and can be imple
mented in a high-level procedural and/or object-oriented pro
gramming language, and/or in assembly/machine language.

50

55

as a machine-readable signal. The term “machine-readable
signal” refers to any signal used to provide machine instruc
tions and/or data to a programmable processor.
To provide for interaction with a user, the systems and
techniques described here can be implemented on a computer
having a display device (e.g., a CRT (cathode ray tube) or
LCD (liquid crystal display) monitor) for displaying infor
mation to the user and a keyboard and a pointing device (e.g.,
a mouse or a trackball) by which the user can provide input to
the computer. Other kinds of devices can be used to provide
for interaction with a user as well; for example, feedback
provided to the user can be any form of sensory feedback
(e.g., visual feedback, auditory feedback, or tactile feed
back); and input from the user can be received in any form,
including acoustic, speech, or tactile input.
The systems and techniques described here can be imple
mented in a computing environment that includes a back-end
component (e.g., as a data server), or that includes a middle
ware component (e.g., an application server), or that includes
a front-end component (e.g., a client computer having a
graphical user interface or a Web browser through which a
user can interact with an implementation of the systems and
techniques described here), or any combination of suchback
end, middleware, or front-end components. The components
of the environment can be interconnected by any form or
medium of digital data communication (e.g., a communica
tion network). Examples of communication networks include
a local area network (“LAN”), a wide area network (“WAN).
and the Internet.

60

65

The computing environment can include clients and serv
ers. A client and server are generally remote from each other
and typically interact through a communication network. The
relationship of client and server arises by virtue of computer
programs running on the respective computers and having a
client-server relationship to each other.
A number of implementations have been described. Nev
ertheless, it will be understood that various modifications

may be made. For example, information included in any of
the data structures can be handled as metadata describing the

US 7,587,237 B2
15

16
ting the information describing events that have measures of
merit among a certain number of the most meritorious in the
first of the categories.

data structures themselves and hence still associated with the

data structures. An event can be associated with a time span
based on the merit of the event exceeding a certain threshold.
All events that exceed such a threshold can remain associated

4. The method of claim 1, wherein:

with the time span, rather than be discarded. Accordingly,
other implementations are within the scope of the following

the first proper subset of the events comprises events that
occur within a certain time span and excludes events
occurring outside the certain time span.

claims.

5. The method of claim 4, wherein:
What is claimed is:

1. A method of monitoring a cardiac biological signal using
electrocardiographic monitoring instrumentation, compris
ing:
receiving, at the electrocardiographic monitoring instru
mentation, the cardiac biological signal that includes
information describing events, wherein events comprise
periods in time when an information content of the car
diac biological signal is of increased relevance to a par
ticular purpose and the events are demarcated by periods
of time that are not of increased relevance to the particu
lar purpose;
at the electrocardiographic monitoring instrumentation,
classifying the events into two or more categories based
on cardiac conditions indicated by the information
describing each event;
at the electrocardiographic monitoring instrumentation,
determining a measure of merit of the information
describing each event, wherein the measure of merit
embodies a severity of the cardiac condition associated

10

15

of these events.

8. The method of claim 1, wherein classifying the events
comprises classifying the events based on a frequency of
heartbeats.
25

30

mentation, the measure of merit of information describ

ing each event with a first merit criterion;
transmitting, for medical purposes, information describing
a first proper subset of the events in a first of the catego
ries that have merits meeting the first merit criterion
from the electrocardiographic monitoring instrumenta

35

tion to a remote medical receiver, wherein the remote
medical receiver is not located at the same site at the

electrocardiographic monitoring instrumentation;
at the electrocardiographic monitoring instrumentation,
discarding information describing a second proper Sub
set of the events in the first of the categories that have
measures of merit that fail to meet the first merit crite
r1on;

40

45

mentation, the measure of merit of information describ
50

55

merit criterion; and

at the electrocardiographic monitoring instrumentation,
discarding information describing a fourth proper Subset
of the events in the second of the categories that have

10. The method of claim 9, wherein associating the infor
mation describing each event in the first proper subset with
the information describing the time span comprises associat
ing the information describing each event in the first proper
subset with the information describing the time span when the
event measure of merit is among a predetermined number of
the most meritorious events in the first of the categories.
11. The method of claim 9, wherein associating the infor
mation describing each event in the first proper subset with
the information describing the time span comprises generat
ing a data structure having a time stamp associated with the
information describing the event.
12. The method of claim 9, wherein associating informa
tion describing each event in the first proper Subset comprises
associating raw data drawn from an electrocardiogram with
information describing the time span in which the event
occurred.

comparing, at the electrocardiographic monitoring instru
ing each event with a second merit criterion;
transmitting, for medical purposes, information describing
a third proper subset of the events in a second of the
categories that have measures of merit meeting the sec
ond merit criterion from the electrocardiographic moni
toring instrumentation to the remote medical receiver,
wherein the second category differs from the first cat
egory and the second merit criterion differs from the first

9. The method of claim 1, further comprising associating
information describing each event in the first proper Subset
with information describing a time span in which the event
occurred.

with the event and an amount of noise in the information

describing the event;
comparing, at the electrocardiographic monitoring instru

the first proper subset of the events comprises events that
occur within a predetermined time span and excludes
events occurring outside the predetermined time span.
6. The method of claim 1, wherein receiving the cardiac
biological signal comprises receiving a measurement of elec
trical potential.
7. The method of claim 1, wherein classifying the events
comprises classifying the events as one or more of anasystole
event, a tachycardia event, a bradycardia event, and an atrial
fibrillation/flutter event based on identifying characteristics

13. The method of claim 9, wherein the cardiac biological
signal comprises a stream of information describing a state of
a heart of a biological system.
14. The method of claim 1, further comprising comparing
a first measure of merit of information describing a first event
with a second measure of merit of information describing a
second event to identify a more meritorious event.
15. The method of claim 14, further comprising creating an
episode describing the more meritorious event.
16. The method of claim 15 wherein creating the episode
comprises Summarizing a relevance of the information
describing the more meritorious event.
17. The method of claim 1, wherein the cardiac biological
signal comprises an electrocardiogram signal.
18. The method of claim 1, wherein:

a first event described in the cardiac biological signal has a
60

first duration;

measures of merit that fail to meet the second merit
criterion.

a second event described in the cardiac biological signal

2. The method of claim 1, wherein the first merit criterion

the first duration is not equal to the second duration.
19. The method of claim 1, wherein classifying the events
comprises classifying a first event as a tachycardia event.
20. The method of claim 1, wherein classifying the events
comprises classifying a first event as a bradycardia event.

has a second duration; and

is based on measures of merit of other events in the first of the

categories.
3. The method of claim 1, wherein transmitting the infor
mation describing the first proper Subset comprises transmit

65

US 7,587,237 B2
17
21. The method of claim 1, wherein classifying the events
comprises classifying a first event as an atrial fibrillation/

18
discarding information describing a second proper Subset
of the events in the first of the categories that have

flutter event.

measures of merit that fail to meet the first merit crite

22. A method of monitoring a cardiac biological signal
using electrocardiographic monitoring instrumentation,
comprising:
receiving a cardiac biological signal that includes informa
tion describing events at the electrocardiographic moni
toring instrumentation, wherein events comprise peri

rion;

ods in time when an information content of the cardiac

comparing the measure of merit of information describing
each event with a second merit criterion;

transmitting, for medical purposes, information describing
a third proper subset of the events in a second of the
categories that have measures of merit meeting the Sec
10

biological signal is of increased relevance to a particular
purpose and the events are demarcated by periods of
time that are not of increased relevance to the particular

merit criterion; and

purpose;

determining, at the electrocardiographic monitoring

15

instrumentation, a measure of merit of information

26. The article of claim 25, wherein the first merit criterion
is based on measures of merit of other events in the first of the

categories.
27. The article of claim 25, wherein the operations further
comprise associating information describing each event in the
first proper Subset with information describing a time span in

mentation, the measure of merit of information describ

which the event occurred.
25

receiver; and

discarding information describing a second proper Subset
of the events that have measures of merit that fail to meet

the merit criterion at the electrocardiographic monitor
ing instrumentation.
23. The method of claim 22, wherein determining the mea
Sure of merit of the information describing each event com
prises determining the amount of noise in the information
describing the event.
24. The method of claim 22, wherein determining the mea
Sure of merit of the information describing each event com
prises determining a signal dropout during the event.
25. An article comprising one or more machine-readable
media storing instructions operable to cause one or more
machines to perform operations for monitoring a cardiac
biological signal using electrocardiographic monitoring
instrumentation, the operations comprising:
receiving the cardiac biological signal that includes infor
mation describing events, wherein events comprise peri

discarding information describing a fourth proper Subset of
the events in the second of the categories that have
measures of merit that fail to meet the second merit
criterion.

describing each event, wherein the measure of merit
embodies both the severity of the cardiac condition indi
cated by the information describing the event and an
amount of noise in the information describing the event;
comparing, at the electrocardiographic monitoring instru
ing each event with a merit criterion;
transmitting, for medical purposes, information describing
a first proper subset of the events that have measures of
merit meeting the merit criterion from the electrocardio
graphic monitoring instrumentation to a remote medical

ond merit criterion to the remote medical receiver,

wherein the second category differs from the first cat
egory and the second merit criterion differs from the first

30

35

28. The article of claim 27, wherein associating the infor
mation describing each event in the first proper subset with
the information describing the time span comprises associat
ing the information describing each event in the first proper
subset with the information describing the time span in which
the event measure of merit is among a predetermined number
of the most meritorious events in the first of the categories.
29. The article of claim 27, wherein associating the infor
mation describing each event in the first proper subset with
the information describing the time span comprises generat
ing a data structure having a time stamp associated with the
information describing the event.
30. The article of claim 25, wherein the operations further
comprise creating an episode describing the more meritorious
event.

40

45

31. The article of claim 30, wherein creating the episode
comprises Summarizing a relevance of the information
describing the more meritorious event.
32. The article of claim 25, wherein the cardiac biological
signal comprises an electrocardiogram signal.
33. The article of claim 25, wherein:

ods in time when an information content of the cardiac

a first event described in the cardiac biological signal has a

biological signal is of increased relevance to a particular
purpose and the events are demarcated by periods of
time that are not of increased relevance to the particular

a second event described in the cardiac biological signal

first duration;
50

purpose;

classifying the events into two or more categories based on
cardiac conditions indicated by the information describ
ing each event;
determining a measure of merit of the information describ
ing each event, wherein the measure of merit embodies
a severity of the cardiac condition associated with the

55

flutter event.

event and a an amount of noise in the information

describing the event;
comparing the measure of merit of information describing

60

each event with a first merit criterion;

transmitting, for medical purposes, information describing
a first proper subset of the events in a first of the catego
ries that have merits meeting the first merit criterion to a
remote medical receiver, wherein the remote medical

has a second duration; and

the first duration is not equal to the second duration.
34. The article of claim 25, wherein classifying the events
comprises classifying a first event as a tachycardia event.
35. The article of claim 25, wherein classifying the events
comprises classifying a first event as a bradycardia event.
36. The article of claim 25, wherein classifying the events
comprises classifying a first event as an atrial fibrillation/

65

37. An article comprising one or more machine-readable
media storing instructions operable to cause one or more
machines to perform operations for monitoring a cardiac
biological signal using electrocardiographic monitoring
instrumentation, the operations comprising:
receiving a cardiac biological signal that includes informa
tion describing events, wherein events comprise periods

receiver is not located at the same site at the electrocar

in time when an information content of the cardiac bio

diographic monitoring instrumentation;

logical signal is of increased relevance to a particular

US 7,587,237 B2
19
purpose and the events are demarcated by periods of

20
discarding information describing a second proper Subset

time that are not of increased relevance to the particular

of the events that have measures of merit that fail to meet

purpose;

the merit criterion.

determining a measure of merit of information describing

38. The article of claim 37, wherein determining the mea
Sure of merit of the information describing each event com
the severity of the cardiac condition indicated by the
information describing the event and an amount of noise prises determining the amount of noise in the information
in the information describing the event;
describing the event.
comparing the measure of merit of information describing
39. The article of claim 37, wherein determining the mea
each event with a merit criterion;
10 sure of merit of the information describing each event com
transmitting, for medical purposes, information describing prises determining a signal dropout during the event.
a first proper subset of the events that have measures of
merit meeting the merit criterion to a remote medical
each event, wherein the measure of merit embodies both

receiver; and

UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRECTION
PATENT NO.

: 7,587,237 B2

Page 1 of 1

APPLICATION NO. : 10/770702

DATED

: September 8, 2009

INVENTOR(S)

: Korzinov et al.

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

On the Title Page:
The first or sole Notice should read --

Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b)
by 487 days.

Signed and Sealed this
Twenty-first Day of September, 2010

David J. Kappos
Director of the United States Patent and Trademark Office

Exhibit B

US00794.1207B2

(12) United States Patent

(10) Patent No.:

Korzinov

US 7,941,207 B2

(45) Date of Patent:

*May 10, 2011

(54) CARDIAC MONITORING

4,977,899 A

(75) Inventor: Lev Korzinov, San Diego, CA (US)

5, 191,891 A
5,197.479 A

(73) Assignee: Cardionet, Inc., San Diego, CA (US)

5,365,935 A

5,421,342 A

6/1995 Mortara

(*) Notice:

Subject to any disclaimer, the term of this

5,423,863. A

6/1995 Felblinger et al.

U.S.C. 154(b) by 1104 days.

5,522,396 A

6/1996 Langer et al.

This patent is Subject to a terminal disclaimer.

5,546,950 A

8, 1996 Schoeckert et al.
(Continued)

D326,716 S

5,226,425 A

patent is extended or adjusted under 35

A

(21) Appl. No.: 11/674,053

(22) Filed:

Oaa

10-234688

9, 1998

Jun. 30, 1985, 164 pages.

Jan. 21, 2004, now Pat. No. 7,194,300.

(Continued)

(51) Int. Cl.
A6 IB5/04
(2006.01)
(52) U.S. Cl. ....................................................... 6OO/518

(58) Field of Classification Search .......... 600/509 521;

607/25
See application file for complete search history.
References Cited
U.S. PATENT DOCUMENTS

4,621.617 A * 11/1986 Sharma ........................ 600/16
4,622,979 A
4,630,204. A
4,938,228 A

g E. E.

Biomedical Computer Laboratory, Institute for Biomedical Comput
ing, Washington University, “Progress Report No. 21.” Jul. 1, 1984

(63) Continuation of application No. 10/762,887, filed on

4,920,489 A

7, 1993 Righter

11, 1994 E. et al.

OTHER PUBLICATIONS

Jun. 7, 2007

Related U.S. Application Data

(56)

3/1993 Righter
3, 1993 Hubelbank et al.

(Continued)

Prior Publication Data

US 2007/O129642 A1

6/1992 Mortara

FOREIGN PATENT DOCUMENTS
JP

Feb. 12, 2007

(65)

12/1990 Digby et al.

1 1/1986 Katchis et al.
12/1986 Mortara et al.
4, 1990 Hubelbank
7/1990 Righter et al.

4,951,681 A

(57)

ABSTRACT

Systems and techniques for monitoring cardiac activity. In
one aspect, a method includes collecting information describ
ing the variability in heart rate over a series of beats, desig
nating variability at a lower end of physiological values as
being largely irrelevant to atrial fibrillation, designating Vari
ability in a midrange of physiological values as being indica
tive of atrial fibrillation, designating variability in an upper
range of physiological values as being negatively indicative
of atrial fibrillation, and determining a relevance of the vari
-- - - ability described in the collection to atrial fibrillation.

8, 1990 Mortara

4,958,641 A

Primary Examiner — George Manuel
(74) Attorney, Agent, or Firm — Fish & Richardson P.C.

9/1990 Digby et al.

25 Claims, 7 Drawing Sheets

A 10
- - - -- --

310

SIGNAL

AMPLIFIER?
PROCESSOR

320

BEAT
DETECTOR

DETECTOR

DECISION
LOGIC

EVENT
GENERATOR

US 7,941,207 B2
Page 2
U.S. PATENT DOCUMENTS

5,581,369
D377,983
5,634,468
5,678,562
5,704,351
5,730, 143
5,840,038
5,931,791
5,959,529
D414,870
5,966.692
5,987,352
6,102,856
6,178,347
6,225,901
6,226,599
6,269,263
6,287,252
6,289.243
6,308,094
6,366,871
6,490,479
6,496,731
6,564,077
6,569,095
6,664,893
6,697,655
6,871,089
6,922,584
7,187.965
7,222,054
7,311,665
7,542,878
7,693,574
2002fOO65473
2002fOO67256
2002/O128804
2002.0193838
2003/0028442
2003, OO694.86
2003, OO69487
2003/0093.125
2003/O122677
2003/O144597
2003/0172940
2004/0010201
2004/0085186
2005/01 13703
2005/01 13705

12, 1996
2, 1997
6, 1997
10, 1997
1, 1998
3, 1998
11, 1998
8, 1999
9, 1999
10, 1999
10, 1999
11, 1999
8, 2000
1, 2001
5, 2001
5, 2001
T/2001
9, 2001
9, 2001
10, 2001
4, 2002
12, 2002
12, 2002
5/2003
5/2003
12, 2003
2, 2004
3, 2005
7/2005
3, 2007
5/2007
12, 2007
6, 2009
4, 2010
5, 2002
6, 2002
9, 2002
12, 2002
2, 2003
4, 2003
4, 2003
5/2003
T/2003
T/2003
9, 2003
1, 2004
5, 2004
5/2005
5/2005

Righter et al.
Sabri et al.
Platt et al.
Sellers
Mortara et al.

Schwarzberg

Xue et al.
Saltzstein et al.

Kail, IV

Saltzstein et al.

Langer et al.
Klein et al.
Groffet al.
Olsson

Kail, IV

Namiki
Ohnishi et al.

Lugo
Lin et al.
Shusterman et al.
Geva
Bock
Lovett
Mortara

Eggers
Eveland et al.

Sueppel et al.
Korzinov et al.

Wang et al.
Bischoff et al.
Geva
Hawthorne et al.
Nanikashvili
Wessels

Wang et al.
Kail, IV
Geva
Lovett

Wagstaffetal.
Sueppel et al.
Mortara
Zhu et al.

Kail, IV

Bock

Rogers et al.
Korzinov et al.
Eveland et al.

Farringdon et al.
Fischell et al.

2005, 0119833
2005/0203349
2006/0010201
2007/010O213

A1
A1
A1
A1

6/2005
9, 2005
1/2006
5/2007

Nanikashvili
Nanikashvili
Korzinov
Dossas et al.

FOREIGN PATENT DOCUMENTS
JP
JP
JP
WO
WO
WO
WO
WO
WO
WO
WO
WO

2002-301039
2004-5 17677
2005-523785
WO O2/O56961
WO O2/O852OO
WO O2/O852O1
WO O2/O86792
WO O2/O86793
WO 02/086835
WO O2/O86837
WOO3,O77752
WOO3,O77755

A2
A2
A1
A2
A2
A1
A1
A1

10, 2002
6, 2004
8, 2005
T 2002
10, 2002
10, 2002
10, 2002
10, 2002
10, 2002
10, 2002
9, 2003
9, 2003

OTHER PUBLICATIONS

Savi Wireless—Mobile Cardiac Telemetry Brochure, published by at
least May 2009, 12 Pages, Medicomp, Melbourne, Florida.
Extended European Search Report in Application No./Patent No.
0571 1728.5-2305,1706031

PCT/US2005/001849 mailed on Mar.

4, 2010, 13 pages.
Cerutti, S. et al., “Analysis of the Dynamics of RRInterval Series for
the Detection of Atrial Fibrillation Episodes.” Department of Bio
medical Engineering, Polytechnic University, Milano Italy, Comput
ers in Cardiology 1997, vol. 24, pp. 77-80.
Canadian Office Action dated May 21, 2009.
Japanese Office Action in Japanese Patent Application No. 2006
54.7636 dated Jun. 26, 2009 with an uncertified translation.
Description of Telephone Discussion with Examiner at the Japanese

Patent Office who is examining Japanese Patent Application No.
2006-547636 (Japanese Appeal No. 2010-4938) (2 pages).
Machine translation of JP 10-234688 from Patent Abstracts of Japan
(7 pages).
Cerutti et al., Analysis of the dynamics of RR interval series for the
detection of atrial fibrillation episodes, Computers in Cardiology, pp.
77-80 (1997).
Description of Telephone Discussion with Examiner at the Japanese
Patent Office who is examining Japanese Patent Application No.
2006-547636 (Japanese Appeal No. 2010-4938) (2 pages).
Machine translation of JP 10-234688 from Patent Abstracts of Japan
(7 pages).

* cited by examiner

U.S. Patent

May 10, 2011

Sheet 1 of 7

US 7,941,207 B2
100

RECEIVER

-

205

R

N

R

"N

N

CD

3.
c
>

--

--

215

220

210
Time

225

FIG. 2
110
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4----

310

320

SIGNAL

AMPLIFIER/
PROCESSOR

DECISION
LOGIC

EVENT

GENERATOR

U.S. Patent

May 10, 2011

Sheet 2 of 7

US 7,941,207 B2
Measure

AF-type Variability

Variability

Measure

Variability
425

415

O

430

End of AF-type
Variability

FIG. 4
600

605

610

ADD WEIGHTED COMPARISON TO A
COLLECTION OF WEIGHTED COMPARISONS
FOR RECENT BEATS

615

620

F.G. 6A
0.4
O.3

1.

0.2

A 0.1
O

O

0.5

1

15

2

U.S. Patent

May 10, 2011

Sheet 3 of 7

US 7,941,207 B2
500

RECEIVE TIMING OF RECENT BEATS

505

DETERMINE VARIABILITY IN RECENT RTO R

510

INTERVALS

IDENTIFY RELEVANCE OF VARIABILITY TO

515

AF

520

VARIABILITY INDICATIVE
OF AF2

Y
525

INITIATEAF EVENT
->

RECEIVE TIMING OF RECENT BEATS

530

DETERMINE VARIABILITY RECENT RTO R
INTERVALS

535

DETERMINE RELEVANCE OF VARIABILITY

540

TO AF

545

VARIABILITY INDICATIVE
OF END OF AF2

Y
TERMINATEAF EVENT

550

F.G. 5

U.S. Patent

May 10, 2011

Sheet 4 of 7

US 7,941,207 B2

F.

S{}{}
-- - - -- - - -- - - - - ----- - --- ------ - ---- ----

- - - - - - - - - - - - - - - - - - r - r in r

3{}5

-4-

SNA -

AF

AMFFER

DETECTOR

RCCESSCR
3EA

iDEECTOR

| DECISION
LOGIC

EVENT
{GENERAC3R.

U.S. Patent

May 10, 2011

Sheet 5 Of 7

US 7,941,207 B2

420

425
415

410
405

End of V-TACH
430

Event

Three Consecutive
Ventricular Beats

910

915

905

FIG. 9

U.S. Patent

May 10, 2011

Sheet 6 of 7

US 7,941,207 B2
1000

f
COMPARE RECENT RTO RINTERVALS WITH
PREVIOUS RTO RINTERVALS

1005

RECEIVE VENTRICULAR BEAT OCCURRENCE
INDICATOR

1010

CREATE ARRAY INCLUDING RECENT
COMPARISONS AND VENTRICULAR BEAT
OCCURRENCE INDICATORS

1015

WEIGHT COMPARISONS IN ACCORDING TO
LIKELIHOOD OF RELEVANCE TO AF

1020

ASSIGN PRESET VALUE TO COMPARISONS
ASSOCIATED WITH VENTRICULAR BEATS

1025

CALCULATEAVERAGE OF WEIGHTED

1030

COMPARISONS (INCLUDING THOSE
ASSIGNED PRESET VALUE)
1035
AVERAGE > 0.22 FOR LAST FIVE

Y
TRIGGER START OF AF EVENT INCLUDING

1040

RECENT BEATS

FIG. 10

U.S. Patent

May 10, 2011

Sheet 7 Of 7

US 7,941,207 B2

1100

COMPARE RECENT RTO RINTERVALS WITH
PREVIOUS RTO RINTERVALS

RECEIVE VENTRICULAR BEAT OCCURRENCE

1005

1010

INDICATOR

CREATE ARRAY INCLUDING RECENT
COMPARISONS AND VENTRICULAR BEAT
OCCURRENCE INDICATORS

1015

WEIGHT COMPARISONS IN ACCORDING TO
LIKELIHOOD OF RELEVANCE TO AF

O20

ASSIGN PRESET VALUE TO COMPARISONS
ASSOCIATED WITH VENTRICULAR BEATS

O25

CALCULATE AVERAGE OF WEIGHTED

1030

COMPARISONS (INCLUDING ANY ASSIGNED
PRESET VALUES)
1 105

VENTRICULAR BEAT FOR
LAST THREE BEATS?

TRIGGER END OF AF EVENT INCLUDING

1110

RECENT BEATS

START AND TERMINATE VENTRICULAR
TACHYCARDIA EVENT

AVERAGE < 0.08?

TRIGGER END OF AF EVENT

125

FIG 11

1115

US 7,941,207 B2
1.

2
beat. The relevance of the variability to atrial fibrillation can
be determined by determining an average relevance of vari
ability in a collection of R to R intervals.
The beat-to-beat variability can be determined in a series of
Successive beats, e.g., by determining the variability in an

CARDAC MONITORING
CROSS-REFERENCE TO RELATED
APPLICATIONS

This application claims the priority of U.S. application Ser.

interval between successive R-waves. The event can be iden

No. 10/762,887, filed on Jan. 21, 2004, now U.S. Pat. No.

tified by comparing the relevance of the variability to a first
predetermined amount of relevance. Further, the relevance of
the variability in the event can be compared to a second
predetermined amount of relevance to identify the end of the
event. The second predetermined amount can be lower than
the first predetermined amount.
A method can include collecting information describing
the variability in heart rate over a series of beats, designating
variability at a lower end of physiological values as being
largely irrelevant to atrial fibrillation, designating variability
in a midrange of physiological values as being indicative of
atrial fibrillation, designating variability in an upper range of
physiological values as being negatively indicative of atrial
fibrillation, and determining a relevance of the variability

7,194,300 as a continuation application. The contents of U.S.
application Ser. No. 10/762,887 are incorporated herein by
10

reference.
BACKGROUND

The following description relates to cardiac monitoring,
for example, by monitoring cardiac electrical activity.
The electrical activity of the heart can be monitored to track
various aspects of the functioning of the heart. Given the
volume conductivity of the body, electrodes on the body
surface or beneath the skin often display potential differences
related to this activity. Anomalous electrical activity can be
indicative of disease states or other physiological conditions
that can range from benign to deadly.
One example of Such a physiological condition is atrial
fibrillation. Atrial fibrillation involves the loss of synchrony
between the atria and the ventricles. In complex atrial fibril
lation, long-lived wavelets of depolarization travel along cir
cular paths in the atria. This can lead to irregular ventricular
beating as well as blood stagnation and clotting in the atria.
Atrial fibrillation is among the most common forms of
cardiac arrhythmia and may affect more than two million
people annually. Atrial fibrillation has been associated with
stroke, congestive heart failure, and cardiomyopathy.
Another example of such a physiological condition is atrial
flutter. Atrial flutter also involves the loss of synchrony
between the atria and the ventricles. In atrial flutter, multiple
atrial waveforms reach the atrioventricular (AV) node during
each ventricular beat due to, e.g., atrial scars, an atrial infarc
tion, or a re-entrant circuit encircling a portion of the right
atrium.
Atrial flutter is less common than atrial fibrillation but is

15

described in the collection to atrial fibrillation.

25

30

DRR(n) = ABS

RR(n, n - 1)
1
(n) = (Notes i).

35

40

SUMMARY
45

The cardiac monitoring systems and techniques described
here may include various combinations of the following fea
tures.

55

The end of the event can be identified based on the deter
mined relevance. An event state associated with atrial fibril

lation can be transitioned into in response to identification of
60

from an ambulatory patient. The relevance of the variability to
atrial fibrillation can be determined by receiving information
identifying a Ventricular beat and assigning a preset value
indicating that the variability is negatively indicative of atrial
fibrillation.

A ventricular tachycardia event can be identified based at
least in part on the information identifying the Ventricular

relevance of the variability can be the relevance of the vari
ability to sustained atrial fibrillation. The series of R to R
intervals can be a continuous series of R to Rintervals.

WaC.

the event. The event can be transmitted to a remote receiver

The variability at the lower end of physiological values can
be designated as being largely irrelevant by designating infor
mation related to factors DRR(n) less than about 0.0.2 as
being largely irrelevant. The variability at the midrange of
physiological values can be designated as being indicative of
atrial fibrillation by designating information related to factors
DRR(n) greater than about 0.02 and less than about 0.15 as
being indicative of atrial fibrillation. The variability at the
upper range of physiological values can be designated as
being negatively indicative of atrial fibrillation by designating
information related to factors DRR(n) greater than about
0.157 as being negatively indicative of atrial fibrillation.
Information describing the variability can be collected by
collecting the variability in heart rate over a series of between
20 and 200 of the recent R to R intervals. The determined

50

lation event and anatrial flutter event based on the determined

relevance. The event is a period in time when the information
content of the cardiac electrical activity is of increased rel

of beats can be collected. The collected information can be a

function of a ratio of a first R to Rinterval and an immediately
preceding R to R interval. Such as information related to
factor DRR(n) as given by

also associated with stroke, congestive heart failure, and car
diomyopathy.

A method can include determining a beat-to-beat variabil
ity in cardiac electrical activity; determining a relevance of
the variability to one of atrial fibrillation and atrial flutter
using a non-linear statistics, identifying one of an atrial fibril

The variability can be designated by multiplying the infor
mation describing the variability by a weighting factor. Infor
mation describing a variability in R to Rintervals over a series

65

A method can include comparing recent R to R intervals
with preceding R to R intervals to yield a collection of com
parisons, weighting the comparisons according to a likeli
hood that the comparisons are relevant to atrial fibrillation,
and determining the average relevance of the collection to
atrial fibrillation. The weighting can include identifying a first
of the recent beats as a ventricular beat and assigning a preset
value to weight the first beat in the collection. The preset value
can be negatively indicative of atrial fibrillation.
The comparisons can be weighted by designating variabil
ity at a lower end of physiological values as being largely
irrelevant to atrial fibrillation and designating variability in a
midrange of physiological values as being indicative of atrial
fibrillation. The comparisons can also be weighted by desig
nating variability in an upper range of physiological values as

US 7,941,207 B2
4
FIG. 8 shows an example of instrumentation for cardiac
monitoring using an electrocardiogram trace.
FIG. 9 shows an example state diagram of a cardiac moni
toring system that accommodates the variability caused by

3
being negatively indicative of atrial fibrillation. A ventricular
tachycardia event can be identified based at least in part on the
identification of the ventricular beat. Recent R to Rintervals

can be compared with immediately preceding R to Rintervals
to yield a collection of comparisons.
The cardiac monitoring systems and techniques may pro
vide one or more of the following advantages. Atrial fibrilla
tion (“AFib’) and/or atrial flutter (“AFlut,” with “AF refer
ring to either) can be distinguished from other types of cardiac
arrhythmia, Such as the normal sinus rhythm irregularity,
irregularity from various types of heartblocks, and the irregu
larity associated with premature ventricular contractions. The
described systems and techniques are a practical approach to
calculating the beat-to-beat irregularity while providing
improved positive predictability of AF. Moreover, the
described systems and techniques are able to identify sus
tained AF episodes, where AF continues for more that
approximately 20 beats and has an increased clinical signifi

5

ventricular beats.

10

FIG. 10 shows a process for determining the variability of
recent R to R intervals and identifying if the variability is
relevant to the onset of AF while accommodating the vari
ability caused by ventricular beats.
FIG. 11 shows a process for determining the variability in
recent R to R intervals and identifying if the variability is
relevant to the termination of AF while accommodating the
variability caused by ventricular beats.
Like reference symbols in the various drawings indicate

15

like elements.
DETAILED DESCRIPTION

CaCC.

For example, when the systems and techniques described
here were used to analyze the MIT-BIHarrhythmia database,
available from MIT-BIH Database Distribution, MIT Room

E25-505A, Cambridge, Mass. 02139, USA, a sensitivity to
AF in excess of 90% and a positive predictivity in excess of

25

96% were obtained.

The described systems and techniques are well-adapted to
monitoring cardiac signals of ambulatory patients who are
away from controlled environments such as hospital beds or
treatment facilities. The cardiac signals obtained from to
ambulatory patients may be noisier and otherwise strongly
impacted by the patients’ heightened levels of activity. Thus,
improved monitoring systems and techniques, such as those
described herein, are required for ambulatory patients.
The described systems and techniques are also well
adapted to real-time monitoring of arrhythmia patients,
where minimal delays in distinguishing between different
types of cardiac arrhythmia can speed the delivery of any
urgent medical care. The described systems and techniques
also require minimal computational resources. Further, the
described systems and techniques do not require training
before different types of cardiac arrhythmia can be distin
guished.
The details of one or more implementations of the inven
tion are set forth in the accompanying drawings and the
description below. Other features, objects, and advantages
will be apparent from the description and drawings, and from

30

35

tation 110 in that receiver 120 is not located at the same site as
40

45

the claims.
DESCRIPTION OF DRAWINGS

FIG. 1 shows a system 100 in which a cardiac signal is
monitored for medical purposes. System 100 includes an
individual 105, instrumentation 110, a signal path 115, and a
receiver 120. Individual 105 can be a patient or a healthy
individual for whom monitoring of one or more biological
signals is deemed to be appropriate. Instrumentation 10 can
include one or more sensing, calibration, signal processing,
control, data storage, and transmission elements Suitable for
generating and processing the cardiac signal, as well as relay
ing all or a portion of the cardiac signal over path 115. Path
115 can be any suitable medium for data transmission, includ
ing wired and wireless media Suitable for carrying optical
and/or electrical signals. The receiver 120 can include a
receiver element for receiving the transmitted signal, as well
as various data processing and storage elements for extracting
and storing the information carried by the transmission
regarding the state of individual 105. The receiver 120 can be
a medical system in that receiver 120 presents information to
medical personnel or to a medical expert system for analysis.
The receiver 120 either can reside remotely from instrumen

50

instrumentation 110 (e.g., at the same hospital, nursing home,
or other medical care facility) or the receiver 120 can reside
within the same general area or vicinity as instrumentation
110 (e.g., within the same room, building, or health care
facility).
FIG. 2 shows an example of a cardiac signal, namely the
trace of a scalar electrocardiogram 200. Electrocardiogram
trace 200 follows a potential difference 205 measured
between two points on the body surface of an individual.
Potential difference 205 changes with time 210 in a manner
characteristic of the physiology and function of an individu
als heart.

FIG. 1 shows a system in which a cardiac signal is moni
tored for medical purposes.
FIG. 2 shows an example of a cardiac signal.
FIG. 3 shows an example of instrumentation for cardiac
monitoring using a cardiac signal.
FIG. 4 shows an example state diagram of a cardiac moni
toring system during cardiac monitoring.
FIG. 5 shows a process for cardiac monitoring for the
detection of an AF event.

55

60

FIG. 6A shows a process for determining the variability in
the recent R to R intervals and identifying if the variability is
relevant to either the onset or termination of AF.

FIG. 6B shows a graph of factor DRR(n) as a function of
RR(n-1,n-2)/RR(n,n-1).
FIG. 7 shows a transformation function for weighting the
variability in the timing of recent beats.

65

Electrocardiogram trace 200 generally includes features
characteristic with particular aspects of cardiac activity. For
example, trace 200 includes a series of QRS complexes 215,
220, 225 associated with activation of the ventricles. QRS
complex 225 includes an R-wave R. QRS complex 220
includes an R-wave R., and QRS complex 215 includes an
R-wave R. The time between successive R-waves can be
referred to as the R to R interval. In particular, the R to R
interval between R-wave R, and R-wave R is RR(n,n-1)
and the Rto Rinterval between R-wave RandR-wave R.
is RR(n-1,n-2).
FIG. 3 shows an example of instrumentation 110 for car
diac monitoring using a cardiac signal Such as electrocardio
gram trace 200. Instrumentation 110 includes a sensor 305, a
signal amplifier/processor 310, a beat detector 315, an atrial
fibrillation/atrial flutter (AF) detector 320, decision logic 325,

US 7,941,207 B2
5
and an event generator 330. Sensor 305 can include two or
more electrodes subject to one or more potential differences
that yield a Voltage signal Such as electrocardiogram trace
200. The electrodes can be body surface electrodes such as
silver/silver chloride electrodes and can be positioned at
defined locations to aid in monitoring the electrical activity of

5

the heart. Sensor 305 can also include leads or other conduc

tors that form a signal path to signal amplifier/processor 310.
Signal amplifier/processor 310 can receive, amplify, and/or
process the Voltage signals. The processing can include fil
tering and digitization. The amplification and remainder of
the processing can occur before or after digitization. Signal
amplifier/processor 310 can provide the amplified and/or pro
cessed signal to beat detector 315.
Beat detector 315 is a device such as a circuit or other

arrangement that identifies the time period between ventricu
lar contractions. For example, beat detector 315 can be a QRS
detector in that it identifies successive QRS complexes (or an
equivalent indicator of Ventricular activity) and determines
the beat-to-beat timing from the time between complexes.
The beat-to-beat timing can be determined by measuring
times between Successive R-waves, such as RR(n,n-1) and
RR(n-1,n-2) in electrocardiogram trace 200 (FIG. 2). Beat
detector 315 can provide information regarding the time
period between ventricular contractions to AF detector 320.
AF detector 320 is a data processing device that analyzes
information regarding the time period between Ventricular

10

reflexive transition 415 and a state transition 420. AF event

state 410 originates a reflexive transition 425 and a state
transition 430. Reflexive transition 415 is associated with a
15

series of variability measurements. State transition 420 is
triggered by the onset of AF-type variability as detected by
such measurements. Reflexive transition 425 is associated

25

contractions to detect AF. The detection of AF can include

distinguishing AF from other sources of Ventricular irregu
larity, Such as premature ventricular contraction, heartblocks,
and normal sinus rhythm irregularity. The detection of AF can
also include distinguishing between short AF episodes and
sustained AF episodes. Short AF episodes generally include
between two and 20 beats and may or may not have clinical
significant, whereas Sustained AF episodes generally include
more than 20 beats and may have relatively greater clinical
significance. The detection of AF can also include the detec
tion of other types of irregularity caused by random refractory
periods of the ventricles.
AF detector 320 can analyze information regarding the
time period between ventricular contractions to detect AF
using non-linear statistical approaches. Non-linear statistics
treats the relationship between variables as something other
than a linear function. Detail regarding an example non-linear
statistical approach to detecting AF is given below. AF detec
tor 320 can provide information regarding the detection of AF
to decision logic 325
Decision logic 325 is a set of instructions for determining
when the AF detected by AF detector 320 has commenced and
terminated. For example, decision logic 325 can be embodied
in a circuit or decision logic 325 can be executed by a data
processing device such as AF detector 320. Decision logic
325 can also trigger the generation of an AF event by event
generator 230.
Event generator 330 is a device Such as a data processing
device that prepares an AF event for handling. An AF event is
a period in time when the information content of the signal
sensed by sensor 305 is deemed to be of increased relevance
to the monitoring of AF. AF events need not be of equal or
predetermined duration. For example, an event associated
with an Sustained AF episode may have a longer duration than
an event associated with a short AF episode.
Event generator 330 can prepare an AF event for handling
by collecting information that Summarizes the relevance of
the event to the detection and/or monitoring of AF. For
example, event generator 330 can excise data associated with
the period identified as AF from the amplified and processed

6
signal output from signal amplifier/processor 310. Eventgen
erator 330 can also redact such data (e.g., by selecting the first
three minutes worth when generating the event). Handling the
AF event can include transmitting the AF event over data link
115 or storing the AF event in a data storage device.
FIG. 4 shows an example state diagram 400 of a cardiac
monitoring system during cardiac monitoring. For example,
state diagram 400 can relate to the operation of an assembly
such as AF detector 320 and decision logic 325 in instrumen
tation 110 (FIG. 3). State diagram 400 includes an idle state
405 and an AF event state 410. Idle state 405 originates a

30

35

40

45

50

with another series of variability measurements. State transi
tion 430 is triggered by the end of AF-type variability as
detected by Such measurements.
In operation, a cardiac monitoring system can start in idle
state 405 and measure the variability of a cardiac signal. For
example, the system can measure the variability in the beat
to-beat timing of Successive R-waves, such as the variability
between RR(n,n-1) and RR(n-1,n-2) in electrocardiogram
trace 200 (FIG. 2). Once the variability has been identified as
AF-type variability, the system transitions to AF event state
410 where the system continues to measure the variability of
the cardiac signal. In AF event state 410, once the AF-type
variability has ended, the system returns to idle state 405.
FIG.5 shows a process 500 for cardiac monitoring, e.g., for
the detection of an AF event. Process 500 can be performed by
one or more data processing devices that perform data pro
cessing activities. The activities of process 500 can be per
formed in accordance with the logic of a set of machine
readable instructions, a hardware assembly, or a combination
of these and/or other instructions. The activities in process
500 can be performed at any of a number of different elements
in a system in which a biological signal is monitored. For
example, in instrumentation 110 (FIG. 3), the activities in
process 900 can be performed at AF detector 320, decision
logic 325, and event generator 330.
The device performing process 500 receives information
regarding the timing of recent beats it 505. The timing infor
mation can be received in discrete amounts (e.g., on a beat
to-beat basis) or in a collection that includes such informa
tion. Using the received timing information, the system
determines the variability in the recent R to Rintervals at 510.
The variability in the R to R intervals can reflect the beat-to
beat change in heart rate over a set period or over a set number
of beats.

55

60

65

The system can also identify the relevance of such variabil
ity to AF at 515. The variability is relevant to AF when it is
associated with a high probability that an individual under
goes AF at or near the time of the recent beats. Relevance can
be identified by comparing the variability to a predetermined
amount of variability or to an amount identified as typical for
the monitored patient.
The system can also determine if the identified relevance of
the variability is indicative of the monitored individual under
going AF at decision 520. If not, the system returns to 505.
This return can correspond to the system remaining in idle
state 405 along reflexive transition 415 in state diagram 400
(FIG. 4). If the system determines that the results of the
monitoring are indicative of the individual undergoing AF,
the system initiates an AF event at 525. This initiation of the
AF event can correspond to the system transitioning to AF

US 7,941,207 B2
7
event state 410 in state diagram 400 (FIG. 4). The initiation of
Such an event can include various activities that lead to the

generation of an event, such as triggering an event generator
to add markers to a data stream Such as electrocardiogram
trace 200 or excising a relevant portion of the data stream.
The system can continue to receive information regarding
the timing of recent beats at 530. Using the received timing
information, the system determines the variability in the
recent R to Rintervals at 535. The system can also identify the
relevance of such variability to the end of AF at 540. The
variability is relevant to the end of AF when it is associated
with an increased probability that AF has halted. Relevance
can be identified by comparing the variability to a predeter
mined amount of variability or to an amount identified as
typical for the monitored patient.
The system can also determine if the identified relevance of
the variability indicates that AF has ended in the monitored
individual at decision 545. If not, the system returns to 530.
This return can correspond to the system remaining in AF
event state 410 along reflexive transition 425 in state diagram
400 (FIG. 4). If the system determines that AF has ended in
the monitored individual, the system returns to 555. This
return can correspond to the system transitioning to idle State
405 in state diagram 400 (FIG. 4).
FIG. 6A shows a process 600 for determining the variabil
ity in the recent R to R intervals and identifying if the vari
ability is relevant to either the onset or termination of AF.
Process 600 can be performed independently or process 600
can be performed as part of a larger collection of activities.
For example, process 600 can be performed as part of process
500, namely as steps 510,515 or as steps 535,540 (FIG. 5).
Various activities in process 600 can also be performed to
trigger state transitions 420, 430 in state diagram 400 (FIG.
4).
The system performing process 600 can compare the most
recent R to R interval (e.g., RR(n,n-1) of FIG. 2) with the
immediately preceding R to Rinterval (e.g., RR(n-1,n-2) of
FIG. 2) at 605. Such a comparison can yield a factor that
reflects the beat-to-beat variability in heart rate. For example,
a factor DRR(n), given by the expression
DRR(t) = ABS

(n) = (or

RR(n, n - 1)

1
lies ..)

10

15

8
Transformation function 700 is adapted to the factor DRR
(n) given in equation 1. In particular, transformation function
700 is adapted to overweight factor DRR(n) when factor
DRR(n) is in a midrange of potential physiological values
(e.g., when DRR(n) is greater than about 0.02 and less than
about 0.15). Transformation function 700 is adapted to
weight factor DRR(n) as being negatively indicative of AF
when factor DRR(n) is at the upper range of potential physi
ological values (e.g., when DRR(n) is greater than about
0.157). Transformation function 700 is adapted to weight
factor DRR(n) as being largely irrelevant to AF when factor
DRR(n) is at the lower range of potential physiological values
(e.g., when DRR(n) is less than about 0.0.2). Transformation
function 700 includes a scalar weighted comparison 705 that
varies as a function of the comparison factor DRR(n) 710. In
particular, weighted comparison 705 varies linearly between
points 715,720,725,730,735. The values of points 715,720,
725,730, 735 are given in Table 1.
TABLE 1
Point

25

30

35

40

Equation 1
45

Comparison DRR(n)

Weight Comparison

715
720
725
730
735

O
O.O2O6
O.O642
0.1427
O.2

O
O.O417
O.9178
O.10OS
-0.3

In operation, weighted comparison 705 for any value of the
factor DRR(n) can be determined by linear interpolation
between the weighted comparisons of points 715, 720, 725,
730, 735. The interpolation can be performed for each value
of the factor DRR(n) as it arises or the results of a certain
number of such interpolations can be stored in a lookup table.
For any value of the factor DRR(n) above 0.2, a weighted
comparison of -0.3 can be assigned.
Returning to FIG. 6A, the system performing process 600
can also add a weighted comparison to a collection of
weighted comparisons for recent beats at 615. For example,
the system can form a FIFO stack or an array of weighted
comparisons having a separate data element for each of
between 10 and 200 (e.g., 100) of the most recent beats. The
system can also determine the relevance of the collection of
weighted comparisons for recent beats to AF at 620. The
collection of weighted comparisons can be relevant to either
the onset or termination of AF.

can reflect the beat-to-beat variability in R to Rinterval and in
heart rate. A graph of factor DRR(n) as a function of RR(n1.n-2)/RR(n,n-1) is shown in FIG. 6B.
The system performing process 600 can also weight the
comparison of the most recent R to Rinterval with the imme
diately preceding R to R interval according to the likelihood
that the results of the comparison are indicative of AT at 610.
The weighting can determine a role that the comparison will
play in Subsequent processing cardiac monitoring activities.
For example, the weighting can include the whole or partial
exclusion of a certain comparisons from Subsequent cardiac
monitoring activities.
One technique for weighting the comparison is through the
use of a transformation, such as transformation function 700

shown in FIG. 7. Transformation function 700 provides
weights that are multiplied by the value of a comparison (e.g.,
factor DRR(n)) to reflect the relevance of the comparison to
AF. The weights provided in transformation function 700 can
be multiplied by the value of every comparison or by a
selected Subset of the comparisons. One technique for select
ing Such a Subset is discussed further below.

50

55

60

65

To determine the relevance, the system can Sum the
weighted comparisons to arrive at a number that represents
the average relevance of the weighted comparisons in the
collection. The system can calculate Such sums for several
beats in a row before determining that the beat-to-beat vari
ability is indicative of the onset or termination of AF. In one
implementation, the system calculates the average of the
weighted comparisons of the beats in the collection and com
pares this average with a first predetermined threshold to
determine if the variability is indicative of the onset of AF and
with a second predetermined threshold to determine if the
variability is indicative of the termination of AF. In general,
the first, onset threshold may be higher than the second,
termination threshold. The difference between the onset and

termination thresholds can introduce hysteresis into the State
transitions to stabilize any system performing process 600.
FIG. 8 shows an example of instrumentation for cardiac
monitoring using an electrocardiogram trace, namely instru
mentation 800. In addition to sensor 305, signal amplifier/
processor 310, AF (AF) detector 320, decision logic 325, and
event generator 330, instrumentation 800 also includes a QRS

US 7,941,207 B2
detector 805 and a ventricular beat detector 810. QRS detec
amplified and processed signal from signal amplifier/proces
sor 310. QRS detector 805 is a device such as a circuit or other
arrangement that identifies the time period between Succes
sive QRS complexes. QRS detector 805 can provide informa
tion regarding the time period between Successive QRS com
plexes to AF detector 320

10
rate. The system performing can also receive an indicator of

tor 805 and ventricular beat detector 810 can both receive an

the occurrence of a ventricular beat at 1010. Such an indicator

can be received, e.g., from a Ventricular beat detector.
The system can create an array or other data structure that
5

Ventricular beat detector 810 is a device such as a circuit or

other arrangement that identifies ventricular beats. Ventricu
lar beats (i.e., premature Ventricular beats) are irregular beats
that interrupt the normal heart rhythm. Ventricular beats gen
erally arise from a Ventricular focus with enhanced automa
ticity. Ventricular beats may also result from reentry within
the His-Purkinje system. The occurrence of ventricular beats
is generally unrelated to AF. For example, the occurrence of
ventricular beats can be used to identify ventricular tachycar
dia (e.g., when there are three or more consecutive ventricular
beats). Ventricular beats may be precipitated by factors such

10

15

as alcohol, tobacco, caffeine, and stress. Ventricular beat

detector 810 can monitor an electrocardiogram trace to iden
tify Ventricular beats. Various systems and techniques for
identifying Ventricular beats can be used. For example, the
Mortara VERITAS Analysis Algorithm, available from Mor
tara Instrument, Inc. (Milwaukee, Wis.), can be used. Ven
tricular beat detector 810 can also provide information
regarding the occurrence of ventricular beats to AF detector

25

32O.

Ventricular beat detector 810 can be housed together with
QRS detector 805. An example of such a joint device is the
ELI 250TM Electrocardiograph available from Mortara
Instrument, Inc. (Milwaukee, Wis.).
Approaches for determining the variability in recent R to R
intervals and identifying if the variability is relevant to either
the onset or termination of AF can accommodate the variabil

ity caused by ventricular beats. FIG.9 shows an example state
diagram 900 of a cardiac monitoring system that accommo
dates the variability caused by ventricular beats. In addition to
idle state 405 and AF event state 410, state diagram 900 also
includes a ventricular tachycardia (V-TACH) event state 905.
Ventricular tachycardia is a rapid succession of Ventricular
contractions (e.g., between 140 and 220 perminute) generally
caused by an abnormal focus of electrical activity in a ven
tricle. Ventricular tachycardia can last from a few seconds to
several days and can be caused by serious heart conditions
Such as a myocardial infarction. AF event state 410 originates
a state transition 910 that is triggered by the occurrence of

30

AF event in the recent beats at 1040. On the other hand, if the

system determines that the average is less than or equal to
0.22 for the last five beats, then the system returns to compare
the recent R to Rintervals with the previous R to Rinterval at
35

40

45

three consecutive ventricular beats. V-TACH event State 905

originates a state transition 910 that is triggered by the end of
a V-TACH event. The end of a V-TACH event can be identi

fied, e.g., when the rate of ventricular contractions falls below
a predetermined value (e.g., a value between 100 and 200
bpm).
FIG. 10 shows a process for determining the variability in
recent R to R intervals and identifying if the variability is
relevant to the onset of AF while accommodating the vari
ability caused by ventricular beats, namely a process 1000.
Process 900 can be performed independently or process 1000
can be performed as part of a larger collection of activities.
For example, process 1000 can be performed as part of pro
cess 500, namely as steps 510,515 (FIG.5). Various activities
in process 1000 can also be performed to trigger state transi
tion 420 in state diagram 900 (FIG.9).
The system performing process 1000 can compare the
recent R to R intervals with the respective, immediately
preceding R to R intervals at 1005 using, e.g., the expression
in Equation 1 to reflect the beat-to-beat variability in heart

includes both the ventricular beat indicators and the R to R

interval comparisons at 1015. The array can include the ven
tricular beat indicators and the R to R interval comparisons
for between 10 and 200 (e.g., 100) of the most recent beats.
The system can also weight the comparisons according to the
likelihood that the R to Rinterval comparisons are relevant to
AF at 1020 using, e.g., transformation function 700 (FIG. 7).
The system can also assign a preset value to the R to R
interval comparisons associated with Ventricular beats at
1025. The preset value can be a penalty value in that the preset
value reflects a decreased likelihood that the variability is
indicative of an AF event. The preset value can be selected in
light of the approaches used to compare the R to R intervals
and to weight Such comparisons. For example, when the R to
R intervals are compared using Equation 1 and the resulting
comparisons are weighted using transformation function 700
(FIG. 7), R to R interval comparisons associated with ven
tricular beats can be assigned a preset value of -0.06 and R to
R intervals comparisons associated with the R to R intervals
immediately succeeding ventricular beats can be assigned a
preset value of Zero.
Using both the weighted and preset timing comparisons,
the system can calculate the average value of an entry in the
array of the most recent beats at 1030. If the system deter
mines that the average is greater than 0.22 for the last five
beats at decision 1035, then the system triggers the start of an

50

1005.

FIG. 11 shows a process for determining the variability in
the recent R to R intervals and identifying if the variability is
relevant to the termination of AF while accommodating the
variability caused by Ventricular beats, namely a process
1100. Process 1100 can be performed independently or pro
cess 1100 can be performed as part of a larger collection of
activities. For example, process 1100 can be performed as
part of process 500, namely as steps 535,540 (FIG. 5). Vari
ous activities in process 1100 can also be performed to trigger
state transitions 430,910,915 in state diagram 900 (FIG.9).
The system performing process 1100 can perform the
activities at 1005, 1010, 1015, 1020, 1025, 1030 as in process
1000. The system can also determine if the last three beats
have been ventricular beats at decision 1105. For example, the
system can determine if the last three beats are marked with a
Ventricular beat occurrence indicator Such as that received at
1010.

55

If the system determines that the last three beats have been
ventricular beats, the system triggers the end of the AF event
at 1110 and, when appropriate, terminates a ventriculartachy
cardia event at 1115. The start and termination of the ven

tricular tachycardia event can transition the state of a system
into and out of a V-TACH event, much like transitions 910,

915 in state diagram 900 (FIG. 9).
60

65

When the V-TACH event has been terminated at 1115 or

when the system determines that the last three beats have not
been ventricular beats at 115, the system then determines if
the average of both the weighted and preset timing compari
sons in the array of the most recent beats has dropped below
0.08 at decision 1120. If the average has not dropped below
0.08, the system returns to compare the recent R to Rintervals
with the previous R to R interval at 1005. On the other hand,

US 7,941,207 B2
11
when the average has dropped below 0.08, the system triggers
the end of the AF event at 1125. This triggering can transition
the state of a system out of an AF event, much like transition
430 in state diagram 900 (FIG. 9).
Various implementations of the systems and techniques
described here can be realized in digital electronic circuitry,
integrated circuitry, specially designed ASICs (application
specific integrated circuits), computer hardware, firmware,
software, and/or combinations thereof. These various imple
mentations can include one or more computer programs that
are executable and/or interpretable on a programmable sys
tem including at least one programmable processor, which
may be special or general purpose, coupled to receive data

12
depending upon the manner in which the timing of beats is
compared. Weight 705 can be interpolated in any of a number
of different ways such as a cubic spline between points 715,
720,725,730, 735. Cardiac monitoring can be performed in
real time or delayed. The values of different parameters can
be changed and useful results still obtained. For example, in
FIG. 7, point 735 can be repositioned to a comparison factor
DRR(n) value above 0.2. Accordingly, other implementations
are within the scope of the following claims.
10

What is claimed is:

and instructions from, and to transmit data and instructions to,

a storage system, at least one input device, and at least one
output device.
These computer programs (also known as programs, soft
ware, Software applications or code) may include machine
instructions for a programmable processor, and can be imple
mented in a high-level procedural and/or object-oriented pro
gramming language, and/or in assembly/machine language.

15

atrial fibrillation and atrial flutter; and

As used herein, the term “machine-readable medium” refers

to any computer program product, apparatus and/or device
(e.g., magnetic discs, optical disks, memory, Programmable
Logic Devices (PLDs)) used to provide machine instructions
and/or data to a programmable processor, including a

25

machine-readable medium that receives machine instructions

as a machine-readable signal. The term “machine-readable
signal” refers to any signal used to provide machine instruc
tions and/or data to a programmable processor.
To provide for interaction with a user, the systems and
techniques described here can be implemented on a computer
having a display device (e.g., a CRT (cathode ray tube) or
LCD (liquid crystal display) monitor) for displaying infor
mation to the user and a keyboard and a pointing device (e.g.,
a mouse or a trackball) by which the user can provide input to
the computer. Other kinds of devices can be used to provide
for interaction with a user as well; for example, feedback
provided to the user can be any form of sensory feedback
(e.g., visual feedback, auditory feedback, or tactile feed
back); and input from the user can be received in any form,
including acoustic, speech, or tactile input.
The systems and techniques described here can be imple
mented in a computing environment that includes a back-end
component (e.g., as a data server), or that includes a middle
ware component (e.g., an application server), or that includes
a front-end component (e.g., a client computer having a
graphical user interface or a Web browser through which a
user can interact with an implementation of the systems and
techniques described here), or any combination of suchback
end, middleware, or front-end components. The components
of the environment can be interconnected by any form or
medium of digital data communication (e.g., a communica
tion network). Examples of communication networks include
a local area network (“LAN”), a wide area network (“WAN).

tOr.

30

nation logic is to accommodate variability in the beat-to-beat
timing caused by Ventricular beats by weighting ventricular
beats as being negatively indicative of the one of atrial fibril
lation and atrial flutter.

35

3. The device of claim 1, wherein the variability determi
nation logic is to compare times between R-waves in three
successive QRS complexes to determine the variability in the
beat-to-beat timing.
4. The device of claim 1, wherein:

the variability determination logic is to represent the vari
ability in the beat-to-beat timing as a factor that is lowest
40

when a first time between beats is close to a second time

between beats; and

45

50

55

the first time immediately proceeds the second time.
5. The device of claim 4, wherein the variability determi
nation logic is to represent the variability in the beat-to-beat
timing as a factor that increases non-linearly when the abso
lute difference between the first time the second time grows.
6. The device of claim 4, wherein the variability determi
nation logic is to represent the variability in the beat-to-beat
timing as a factor that increases more rapidly when the first
time grows less than the second time than when the first time
grows greater than the second time.
7. The device of claim 1, wherein the event generator is to
generate an event by performing operations comprising:
collecting data associated with the collection of beats; and
transmitting the data associated with the collection ofbeats
to a remote receiver.

8. The device of claim 1, wherein the relevance determi

60

nation logic comprises weighting logic to:
weight variability at a lower end of physiological values as
being substantially irrelevant to the one of atrial fibril
lation and atrial flutter;

weight variability in a midrange of physiological values as
being positively indicative of the one of atrial fibrillation

ertheless, it will be understood that various modifications

may be made. Cardiac signals other than Scalar electrocardio
grams such as heart Sounds can be monitored. Other weight
ing approaches and transformation functions can be used,

an event generator to generate an event when the variability
in the beat-to-beat timing is identified as relevant to the
at least one of atrial fibrillation and atrial flutter in light
of the variability in the beat-to-beat timing caused by
ventricular beats identified by the ventricular beat detec
2. The device of claim 1, wherein the relevance determi

and the Internet.

The computing environment can include clients and serv
ers. A client and server are generally remote from each other
and typically interact through a communication network. The
relationship of client and server arises by virtue of computer
programs running on the respective computers and having a
client-server relationship to each other.
A number of implementations have been described. Nev

1. A device, comprising:
a beat detector to identify a beat-to-beat timing of cardiac
activity;
a ventricular beat detector to identify ventricular beats in
the cardiac activity;
variability determination logic to determine a variability in
the beat-to-beat timing of a collection of beats;
relevance determination logic to identify a relevance of the
variability in the beat-to-beat timing to at least one of

and atrial flutter; and

65

weight variability in an upper range of physiological values
as being negatively indicative of the one of atrial fibril
lation and atrial flutter.

US 7,941,207 B2
13
9. The device of claim 8, wherein the weighting logic is
also to weight a beat identified as a Ventricular beat as being
negatively indicative of the one of atrial fibrillation and atrial

14
tifying the at least one of the atrial fibrillation event and the

flutter.

19. The method of claim 13, wherein determining the fac
tor comprises determining DRR(n) as given by

atrial flutter event of the individual based on between 19 and
199 additional factors.

10. The device of claim 1, wherein the relevance determi

nation logic comprises logic to identify the relevance of the
variability using a non-linear function of a beat-to-beat inter
val.

DRR(t) = ABS

(n) = (or

11. The device of claim 1, wherein the beat detector com

prises a QRS detector.
12. The device of claim 1, further comprising a sensor that
includes two or more body surface electrodes subject to one
or more potential differences related to cardiac activity.
13. A method comprising:
receiving information describing a timing of heartbeats of

RR(n, n - 1)

1
lies ..)

10

second heartbeat of the individual, wherein the second

20. An article comprising one or more machine-readable
media storing instructions operable to cause one or more
machines to perform operations, the operations comprising:
determining a beat-to-beat variability in cardiac electrical
activity;
determining a relevance of the variability over a collection
ofbeats to one of atrial fibrillation and atrial flutter using

heartbeat follows immediately after the first heartbeat;
determining a second time between the second heartbeat

identifying one of an atrial fibrillation event and an atrial

15

an individual;

determining a first time between a first heart beat and a

a non-linear function of a beat-to-beat interval; and

and a third heartbeat of the individual, wherein the third

flutter event based on the determined relevance, the

heart beat follows immediately after the second heart

event being a period in time when the information con
tent of the cardiac electrical activity is of increased rel

beat;

determining a factor reflecting the difference between the
first time and the second time, wherein

evance to the one of atrial fibrillation and atrial flutter.
25

21. The article of claim 20, wherein determining the rel
evance comprises:
weighting variability at a lower end of physiological values
as being substantially irrelevant to the one of atrial fibril

30

weighting variability in a midrange of physiological values
as being positively indicative of the one of atrial fibril

the factor is lowest when the first time is close to the

second time, and

the factor increases non-linearly when the absolute dif
ference between the first time the second time grows;
and

identifying at least one of an atrial fibrillation event and an
atrial flutter event of the individual based on the factor.

lation and atrial flutter;

14. The method of claim 13, wherein the factor increases

more rapidly when the first time grows less than the second
time than when the first time grows greater than the second

35

weighting variability in an upper range of physiological
values as being negatively indicative of the one of atrial
fibrillation and atrial flutter; and

time.

determining a relevance of the weighted variability to the

15. The method of claim 13, wherein:

one of atrial fibrillation and atrial flutter.

the method further comprises weighting the factor to
reflectarelevance of the factor to one of atrial fibrillation

and atrial flutter; and

lation and atrial flutter;

40

the identifying of the at least one of the atrial fibrillation
event and theatrial flutter event is based on the weighted

22. The article of claim 20, determining the relevance
comprises:
identifying a beat of the collection as a ventricular beat, and
weighting the beat as being negatively indicative of the one
of atrial fibrillation and atrial flutter.

factor.

16. The method of claim 15, wherein weighting the factor
comprises:
weighting the factor at a lower end of physiological values
as being substantially irrelevant to the one of atrial fibril

23. The article of claim 20, wherein:

45

time between a first heartbeat and a second heartbeat
and a second time between a second heartbeat and a

lation and atrial flutter;

weighting the factor in a midrange of physiological values
as being positively indicative of the one of atrial fibril

third heartbeat;
50

the third heartbeat follows immediately after the second
heartbeat.

24. The article of claim 23, wherein:

fibrillation and atrial flutter.

17. The method of claim 13, wherein:

event and the atrial flutter event is based on the addi
tional factors.

18. The method of claim 17, wherein identifying the at least
one of theatrial fibrillation event and theatrial flutter event of

the individual based on the additional factors comprises iden

the second heart beat follows immediately after the first
heartbeat; and

lation and atrial flutter; and

weighting the factor in an upper range of physiological
values as being negatively indicative of the one of atrial
the method further comprise repeating the determining of
the first time, the determining of the second time, and the
determining of the factor for additional heart beats to
generate additional factors; and
the identifying of the at least one of the atrial fibrillation

determining the beat-to-beat variability comprises deter
mining a factor reflecting the difference between a first

55

the factor is lowest when the first time is close to the second

time; and

the factor increases non-linearly when the absolute differ
ence between the first time the second time grows.
25. The article of claim 24, wherein the factor increases
60

more rapidly when the first time grows less than the second
time than when the first time grows greater than the second
time.

UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRECTION
PATENT NO.

: 7,941,207 B2

APPLICATIONNO.

: 1 1/674053

DATED

: May 10, 2011

INVENTOR(S)

Page 1 of 1

: Lev Korzinov

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Col. 12, Claim 5, line 46, delete “difference between the first time the second time grows. and insert
-- difference between the first time and the second time grows. --

Signed and Sealed this
Second Day of August, 2011

David J. Kappos
Director of the United States Patent and Trademark Office