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, )

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IN THE UNITED STATES DISTRICT COURT FOR THE EASTERN DISTRICT OF PENNSYLVANIA : : : : : : : : : : 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 1 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. 1 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 2 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. 3 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. 4 The ʼ237 and ʼ207 Patents. 2 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, 3 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. 5 Attached hereto as Exhibit A. 4 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 6 Attached hereto as Exhibit B. 5 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 6 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 7 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) 8 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. 9 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 10 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.”). 11 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 12 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. 13 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 14 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. 15 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. 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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. 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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. 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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

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