Mou v. City of San Jose et al

Filing 1347

Case5:07-cv-05740-JF Document25-6

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Mou v. City of San Jose et al

Doc. 1347 Att. 5

Evaluation of a Device for UltrasoundGuided Interstitial Tissue Ablation Using RadiofrequencyElectrosurgery

The Loop Electrode: ~n Vitro

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tion nf ethm~olo hot saline [6. 3; and P noninvasive r method involving high-focused ultrasound [ I The use S. of radiofrequency (W) elccrnwurgery in incerscitial riSsue ahhtion has been limited to monopolar coagulation . around rhe tip of an unlnsulated needle Wlfl. In chis article. I diKuss a technique for intethitial tissue ahlation using mompolar RF electrmurgery in he CUI mode in an i v i m srudy performed under ultran sound guidance. The RF current was applied IO a loop shaped electrode, with superelastic pmperries allowing cannula invoduction before subsequent d o n ofthe rlearasurgical curring eiecrrode resulting in curting ON and isolation o I spheric lesion 1.ntersticially. f

voltage output o up i 350 V depending on the tissue f o impedance m e opuator can limit the maximum voltage output in four steps OcVels 14 ranging from 150 -)
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MATERIALS AND METHO05

ting o a handle. which is connrned IO t R genaator f kF with a 0 . 7 5 1 ~ ~ ' labontory cable (Fa. 1 A l The superelastic properries o the elemode make it parsiMe to f straighten the loop far insertion into a 1 G g a u g e - L m l w inmducer cannula, which is 1% mm long Wigs- 1B a and- I ) After loop srrdightening, the meral thread will C. tend ID conform to the p~shaped loop form. 'The superelastic properties o rhc meal thread are not affened by f rmin o body temperature; however. high temperatures r and stress may affect superelasticity. Fresh Cdlf liver was placed o n a neutral plate connected t an RF elearosurgical generator (Ertuworn o ICC 3 :E W & USA, Adanra, GA). In the cut mode. the gencrator produces an unmodularcd sinusoid wavcfoim o RF voltage with a frequency of 350 K H z The f ourput power can be changed from 0 to 300 W with a

?hr loop elecuode is ma& o a 0.5-mm metal thread f having superebstic prqxnies K o o k Europe. Bjaewrskw. nearnark)- The proximal m i g h t part o the elecf rrodc is 155 rnm long. At the d i d end, the electrode has a shape .ofan open loop with a radius o 1 an 'The f proximal 5 nlni o the stmight parr is insened info thc fitf

mal setting o rhe RF electrmrgical unit. defined as the f output power level at which the highest feSettiOn velocity . & l c h d when the loop eIenrode was n f f e d e d by an appropriate consrant force. This patt af h e srudy was p e r h e d under standardized cob&dons: The loop ckcrrodt was suspended in the bboratory a b k a d was placed vertically over the liver surface (Fig. 2. A d ) l incision was ma& in h e livu with a scalpel, aki drc bop pan o rhc elearode was f inscncd. The straighr pon d the ctKcradt was fixed to an atmmand a constant horizontal pull (0.24 N) r e, a was applied by a w15ght 124.4 g). The loop elemode was connKted KO the monopolar socket o the RF genf era- via the labmatory cable. During different settings OF output power and maximum vollage. RF current was a p p l i i [O &e loop clktrode. During a 3period. the horizonfal movemrnf of the rrsecring and cuuing loop elenrode m m nbsewed and h e traveled distance
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The hrsl scria was unduaken to evaluate the opti-

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?HE LOOP ELECTRODE
with a ruler. With the maximum voltage set at 350 \'. the wtput power u 5 gtadudly i m a s e d from -: 0 to 300 W i 25-W increnimrS. In each setting. five n mmsurcmenu of the rravelecl distance werc obtained. This parr of the experiment was videotaped For dacumenmion and furrha analysis. For statistical analysis, finear regrwion nxt used IO test for a linear increase in elemode mvel35 3 function o wtput power, f In the S K M ~series, esprtriments were performed interwitidly in the calf liver gufded a i d m m i d by ula;isound (System 3535. 7.IMHz curved may mnsducer nith nloullgble needk guide; B&K Medical, Gem tofre. Denmark). The introducer annula was b & d with - the loop electrode and via the d e guide was h s a e d in the liver parenchyma under uhruaund c o n d t a o prederemhed depth o I cm bcnearh dae liver surface. f 'Thc loop pan ofthe denrode was then advanced Fvthcr into the lv through rhe i n d u c e r cannula 'Ihe R geniu F enlor mas switched on Fr appxjmately I xc. during o which rhe superelasrk properties o the elecuode allowed f it t cut itr way h u g h the prenchyma and confm IO o its pre;haped i m p form. me RF genemmr will swilched M again and the handle mu~ed i one to four step. n During this pan OF& procedure. a liver mass was cut off a d isolaad inrerstitially. The lesion was qnrarcd horn the s u m d i g liver parenchyma by a cleavage creared by mating rhe elearmurgially a a i w loop. 7hc loop ekmde was rebaaed through the infmduccr cannula. which subsequently Bas retracted, leaving only a puncture nlark on thr I i surface.A final sonogram of che lesion n?s obtained. DiRerent loop designs and loop sizes m i r e evaluared i tumr o grms'appcarance h e n f of inaahepacic lesion Chamae&iu such as size, f m , and

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high setrings. tklow 200 W. however. pcrmancnr &formation of the loop was not observed unril after nvo w tour curling series. When the voltage Was clunpxl frois level 4 to level 3 or 2, no change in traveling diwnce was obsenrcd: h o w c r . 3~ level 1 (maximum IW V ) a decrease in the naveled distance wac ohscwed. On he b i of hese mlrs. rhc O M ~ Hpower o 200 vs f W and a dugc b e l 2 was used in the intrrsiiiricrl -periments. No pndcal dificultia were ohserved In intnb ducing o mracring dK cannula. perhming rhc W r lesions. OT rnnaing the ekxtrodr into h e introducer cannula d x pcrfbrminfi h e RF m m e n r . During ufirau sound. he inrmducer cannuta and the bry, elean.de could be virrpliaxl in the liver before rhc RF gnrramr was s n W d Wig 4AL The InterstitiaIly placcd loop pact ob rhe earod ode at thb time asurncd a J-shaped ,~ form dmt was h~iy d-rnibk. when the RI: generxor mitchcd on, u i t r a m w i i i i m d~ becau~ elemial noise N i e r initial cutring, the elrcof trade cut its way to Ihe peshpcd loop form widrin appmximatety 2 see- This could be sen on ufrrssoud. Hoa.evcr. the visualization ws d i i d t 1xnu.s.e [he s e m and smoke released a m n d the electrode ta appeared 1s tiny echogenic foci with an acouslic shadow behind. Rotation of the loop elect& was not monitwtd on u h n d IXQWthis parr o rhe procedure f rook place outside [he initial scanning plane. On gros~examination. a slightly ovoid liver lesion (longirudinal diameter 2.0 an. iransveae diarnrrer 1.7 cm)was seen when an ideal semicircular loop with a

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hichess o the coagulation m e w r mollded Meaf ee surements were done with a slide gauge o ruler. Approxr imately 150 lesions made with different loop designs and sires i 15 calf lm w m evaluated. (Kulgcs in loap n in d e s i and size were done a the manufaauds facility. c No sratisrical analyses were performed in this pan of the d y because the data were mosrly qualitative.
RESULTS

In rhe first experimenr. a gcadual increase up LO 200 Win output power resulted in a signFiant incruse in &e tra\-eled distance o h e loop electrock (Fig. 3 At f ) power levels greater than 200 W,.severe sparking and smoke or swam farmation were seen during Ihe C U ~ B procedure. A permmenr deformation of rhc loop shape also occurred after only one cum'ng episode at these
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LOREMZEN

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3 full 360" m r i o n of the loop electrode wirh a cidius of 1.21 cin iuuld be done in approximnirly 16 -4 scc plus ;I few second.for the exm 3045" degxes of mation. Wirhin rhs pcrid of rime. lcsions could be iiisde ill nnc as well 3s in Four s[eps. Rotation in four stcps n-irli an interval Of a few seconds berwrcn the steps n3.c more pracrial &I msirr than the one-step rotation. Fitrthermore. rhr one-step technique more ohcn c-~uwdpemment deformxion of rhe loop than Idid r r strpwke. h The g c .section of the lesion 3nd the corrcsponding ms c.:iviiy of rlic liver showed an even zone of whitish. cmguldicd rissuc [hat n-sapproxiinm4y 1 nini [hick. Thus. ;t rowl rihkdtion of 2.1 crn corresponding to the sphrrid lesion plw 0.2 crn corrcsponding to the cwgulared zones in [he cavity was achieved with [his rechniqw. No difference in coagulxtion was obxrved h e w e e n volwge Irveb 2- 3. and 4. When mating rhr electrode with half s p c d . the steam 3 r d smoke production incrcasrd and thc surf;icc of the laion was i m r r carbonized on mcro-

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prucluced cause an embcljm o inrcrstitial air mire r dissm-on? Many 01 rhsc: gas bubble m y be absorbed in vivo in he sumnding cooler tissue, so that M e emmI retease d gaw will be e a V l l y when the loop rotation is done in fwr step 116). What hap pers after a lesion has been cuc and iFolared h r n thc surrounding tissue? The Itsion is physically sepanted from.the vital tissue. and a doubk aDagulalion zone might prwenr neovascuhrizztkm. In t c v an ischemic ho, necrosis of the lesion with subsequent a t ushould occur- Abxea Formation coukl ParSiMy OCNT in the region ofischemic necpsis within the rrsidual tissue. The loop elearode may have several advantagesover other tissue-desnoying devices. The loop elearode-can be applied to focal disease in dficrent organs such as the liyer, rhe kidney, and the m a t e R can be used

themselves might be relarively inexpensive to produce, and an RF rlecrrosurgical unit b nmilable in a l m w every surgical department. Aniind studies are Fvarrdnred 1 0 further mahare the pgrform-dnce of rhe loop electrode and 10 answer mast of the aforementioned questions. Lomtzen et al. 1171 conducted an animal .study with h e loop electrode and were able to a m w some o rhe quesriozk. f

percuraneowly o during open surgery. The total pmr cedure lam only a Few minutes. The loop elearodes

Annouxicement
The ksron Uni\ersity School o Medicine is sponsoring Advances In Abdominal MRI and MRA. n-11ic.hwill be r held March 15 and 16. 1%. at the Cuplcy Plaza H d in Boston. MA. Fees are 5435 f r physichns and Sj50 for di o orhers. Founeen hours of credit will be awarded. The mume direaor is Josrpli1 Femcci. h l b : For moE infornmtion. contact the Dupamnent of Continuing hleclid Eductltion. Ulwton I-nivrmity Sch'h(~iI of Medicine. 80 E Concord St, Boston. MA 02118; (617) 6384605. .
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