Pulmonary Vein Stenosis after Catheter Ablation: Electroporation versus Radiofrequency Vincent J.H.M. van Driel, Kars G.E.J. Neven, Harry van Wessel, Bastiaan C. du Pré, Aryan Vink, Pieter A.F.M. Doevendans and Fred H.M. Wittkampf Circ Arrhythm Electrophysiol. published online June 23, 2014; Circulation: Arrhythmia and Electrophysiology is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 2014 American Heart Association, Inc. All rights reserved. Print ISSN: 1941-3149. Online ISSN: 1941-3084
The online version of this article, along with updated information and services, is located on the World Wide Web at: http://circep.ahajournals.org/content/early/2014/06/17/CIRCEP.113.001111
Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published in Circulation: Arrhythmia and Electrophysiology can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial Office. Once the online version of the published article for which permission is being requested is located, click Request Permissions in the middle column of the Web page under Services. Further information about this process is available in the Permissions and Rights Question and Answerdocument. Reprints: Information about reprints can be found online at: http://www.lww.com/reprints Subscriptions: Information about subscribing to Circulation: Arrhythmia and Electrophysiology is online at: http://circep.ahajournals.org//subscriptions/
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DOI: 10.1161/CIRCEP.113.001111
Pulmonary Vein Stenosis after Catheter Ablation: Electroporation versus Radiofrequency
Running title: van Driel et al.; PV Stenosis after Ablation: Electroporation vs RF
Vincent J.H.M. van Driel, MD1*; Kars G.E.J. Neven, MD1,2*; Harry van Wessel, BSc1; Bastiaan C. du Pré, MD1; Aryan Vink, MD, PhD3; Pieter A.F.M. Doevendans,, MD,, PhD1; Fred H.M. Wittkampf, PhD1 Department ent ooff Card ent Cardiology, dio i logy, University Medical Center, Cen nte ter, Utrecht, The T e Netherlands; Th N therlands; 2Departm Ne Department m of 3 ologgy, Alfriedd Krupp ol K up Kr pp Hospital, Hosp Ho s it sp ital a , Essen, al Esssen, Germany; Germ many; y De y; Department Depa arttmeent off Pa Path Pathology, th hol olog ogy, og y U University n ve ni v Rhythmology, Medical Medica Me call Center, Centerr, Utrecht, Utrreccht,, The Thee Netherlands. Net ethherllan nds.. * contributed cont n ri nt ribu bute bu t d eq te equally qua uallly
1
Correspondence: V.J.H.M. van Driel, MD University Medical Center Division of Heart and Lungs Department of Cardiology PO Box 85500 3508 GA Utrecht The Netherlands Tel: +31-88-7557269 Fax: +31-88-7555472 E-mail: [email protected]
Journal Subject Codes: [22] Ablation/ICD/surgery
1 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
Abstract: Background - Radiofrequency (RF) ablation inside pulmonary vein (PV) ostia can cause PV stenosis. A novel alternative method of ablation is irreversible electroporation, but the long-term response of PVs to electroporation ablation is unknown. Methods and Results - In 10 six-month old pigs (60-75 kg), the response of PVs to circular electroporation and RF ablation was compared. Ten consecutive non-arcing, 200 joules (J) electroporation applications were delivered 5 to 10 mm inside one of the two main PVs, using a custom deflectable 18 mm circular decapolar catheter. Inside the other PV, circular RF ablation was performed using 30 watts RF applications via an irrigated 4 mm ablation catheter. PV angiograms were made before ablation, immediately after ablation and months d aafter fter ft er 3 mo mont nths nt hs ssurvival. u vii ur PV diameters and heart size were measured. With electroporation ablation, ation, PV ostial osttia iall diameter diam di a e am decreased 11±1 11±10% ±10% ±1 0 directly 0% dir irecctlly after ablation, but had increased incrreased 19±11% aafter in f er 3 months. With RF ft ablation, PV remained V ostial ostial diameter diam meterr decreased dec ecre reas re ased as ed d 223±15% 3±15% 3± % ddirectly irect ctly aafter fterr abl ft ablation bllat atio ionn aand io ndd re rema main ma ined e 77±17% ±17 ±1 ±17% smaller after 21±7% increase during err 3 months m nths mo h than hs tha han pre-ablation pree-ablation e-ab bla lati t onn diameter diaameter despite deesppit ite te a 221 1±7 7% incr creaase in he hheart arrt sizee ddu u aging from months. m 6 too 9 mont n hs. nt Conclusions 200 applications n - In this ns thi his porcine hi porc po r in i e model, mode d l, multiple mullti tipl ipl ple circumferential circumf i ferentia i l 20 00 J electroporation ellecctr t opporationn ap appl p icaa pl inside the PV P ostia ost stia ia do do not not affect afffe f ct c PV PV diameter d amet di am meter ter aatt 33-month -month -m mon onth th h follow-up. fol ollo loww up up.. RF aablation blat bl atio tio i n in iinside side si de P PV V ostia causes considerable PV stenosis directly after ablation, which persists after 3 months.
Key words: catheter ablation, pulmonary vein, pulmonary vein stenosis, radiofrequency, electroporation ablation, radiofrequency ablation
2 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
Introduction Circular electroporation ablation is a novel technique for pulmonary vein (PV) isolation. In a previous animal study, feasibility and safety of circular electroporation for the creation of PV lesions were investigated after a 3-week survival period. One to 4 sequential, non-arcing electroporation applications of 200 joules (J) eliminated PV electrograms in most ostia.1 However, the long-term risk of PV stenosis after electroporation ablation still is unknown. The present animal study was performed to investigate the response of the PV to an excessive number of circular electroporation applications compared too circular RF ablat ablation attio ionn after a 3-month survival period.
Methods All 10 porcine were performed after Animal Experimentation cinee experiments exp xper erim er im imen men e tss w erre pe erf r or orme m d af afte teer prior prio pr ior approval io appr ap prov pr oval ov all ffrom r m th ro thee An A imal im al E Experiment x er xp erim im men e t Committee of the University Guide Care and the h Utrecht Utr trec echt ec htt U n ve ni vers rsit rs ityy and it an in an i ccompliance om mpliaanc ncee wi with t tthe th he G u de ffor ui or C arre an nd Us Usee of Laboratory y Animals Anima Animals. alss.2 E Each Ea ach h aanimal niima mall (6 ((60-75 (60 0-75 75 kkg) g)) wa w was ass in iintubated ntu t ba batteed an aand d an aanesthetized esth es thet th ettiz i ed d aaccording ccor cc o di d ngg tto o standard procedures.1 The porcine left atrium (LA) has 2 PVs suitable for circular catheter ablation: one right or septal PV (RPV) and one inferior PV (IPV) (Figure 1). The RPV enters the LA in close proximity to the atrial septum and fossa ovalis. Before their entrance into the LA, multiple branches merge into a common RPV tubular segment of approximately 10-15 mm in length. The IPV has an approx. 12 mm long tubular segment, and the RPV has an approx. 15 mm long tubular segment after the confluence of a septal and a lateral branch (Figure 1). First, a coronary sinus catheter was inserted via the right jugular vein as fluoroscopic reference for transseptal access. A quadripolar catheter was inserted via the right jugular vein into the right ventricular apex for back-up pacing. Transseptal puncture was performed through 3 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
the right femoral vein. A deflectable 8 French (F) sheath (Agilis™, St. Jude Medical, Minnetonka, MN) facilitated LA catheterization. A temporary screw-in pacing wire (6416, Medtronic Inc., Minneapolis, MN) was inserted via the right femoral vein and fixated in the atrial septum to serve as positional reference for the NavX™ 3D Navigation system (St. Jude Medical, Minnetonka, MN). The LA geometry (including part of the PVs) was reconstructed using the NavX™ system and a standard deflectable quadripolar irrigated ablation catheter with a 4 mm distal electrode (Thermocool™, Biosense Webster Inc., Diamond Bar, CA). Thereafter, angiography of anggio ogr graa both PVs was performed using the antero-posterior (AP), 30 degrees (o) righ right ghht an ght ant anterior teriior ooblique te bliiq bl iq d 300o le left ft aanterior n errio nt ior oblique (LAO) projecti projections tion ti o s for the IPV; on V aand nd AP, 30o cranial andd 30o (RAO) and caudal projections ject je ctions tions for thee RPV. RPV PV V. After Affter te PV angiography, angiograp angio ogrraphy hy,, bo bboth th h PVs PVss were weree alternately altterrnateely ab ablate ablated ed uusing t ora tropo rati tioon or RF ti F energy. y either electroporation Electroporation r i n ab ratio ablation blati tion ion A custom deflectable, ddeflectable efl flecttabl ble 7F 7F, 18 mm circ circular, cii llar decapolar de la el electroporation l tr ati tio catheter thett containing taiiniin 2 mm m ring electrodes separated by 4 mm spacing was introduced through the deflectable sheath in the right femoral vein (Figure 2). This catheter was deployed in the common tubular segment of one of the 2 PVs. Inside the PV, ten cathodal 200 J shocks were delivered between all electrodes of the electroporation catheter and a large indifferent skin electrode (7506, Valley Lab Inc., Boulder, CO) on the shaven lower back. An external, monophasic defibrillator (Lifepak™ 9, Physio-Control Inc., Redmond, WA) was used for energy delivery.1, 3, 4 During each application, current and voltage waveforms were recorded on a dual channel oscilloscope (Tektronix™ TDS 2002B, Beaverton, OR). For each ablation, a different position of the electroporation catheter was chosen to cover the complete tubular segment. Ten applications of 200 J were always
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DOI: 10.1161/CIRCEP.113.001111
delivered even when all PV electrograms had already been eliminated. All electroporation catheter positions were stored with the NavX™ system. After each application, the circular electroporation catheter was reconnected to the NavX™ and electrophysiological recording system (Cardiolab™, General Electric Healthcare, Waukesha, WI) to check electrode integrity and to visualize the electrode positions on the NavX™ system. RF ablation The other PV was circumferentially ablated approximately in the middle of the common tubular segment using sequential 30-watt RF applications delivered via the 4 mm irriga irrigated g ted ablation ablaati tion o on catheter and a saline flow rate of 17 ml/min. Maximal electrode temperature eratur uree was was se sett at 442 2oC C. ly,, m maximal a im ax mal a RF RF duration per vein was set seet at at 15 minutes. s PV V isolation was not the Intentionally, objective or or endpoint enndpoint forr electroporation elecctrropor oraationn orr R or RF F ab ablation. blattioon. angi giiog ogra raph ra aphy was pe performe m d direct me ctly ct ly aft ly ftter ablating abl blat bl atiing both at both hP V usi Vs ing tthe he same PV angiography performed directly after PVs using fluoroscopic i setti ic settings inggs as tthe he ppre-ablation re-ab bla l tiion P PV V angi angiograms. gioggrams. gi Follow-up All catheters were removed and the animals were allowed to recover and kept under daily surveillance. After a 3-month survival period, PV angiography was repeated in all animals using the same techniques as described above. Thereafter, the animals were euthanized by exsanguination. Histological investigation After fixation, the common tubular segment of the both PVs, from antrum to approximately the level of branching, was sliced in 3 circular 4-mm long segments and embedded in paraffin. Elastic van Gieson stained sections of the pulmonary side of each of those segments were scanned. Of each section, the percentage of the perimeter showing a myocardial sleeve was
5 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
measured using ImageJ (National Institutes of Health). The ablated PVs were compared to control PVs from untreated animals. Angiographic analysis Three investigators, blinded for the type of therapy, analyzed all PV angiograms. PV diameters were measured from the PV angiograms taken before ablation, directly after ablation and at 3 months and in all 3 projections. When PV narrowing was obvious at 3 months, PV diameters were always measured at that location. When no narrowing was visible, all measurements were taken in the middle of the common tubular segment. All measurementss were taken at th the he en eendsystolic phase (maximal PV filling and diameter). Diameters measuredd in the the 3 projections projjec ecttio ionns ns were averaged to obtain The o ob obta tain ta in n 1 value value ue for the PV diameter. Th he ppercent ercent change g inn PV P diameter was calculated rel rrelative e ative to the ppre-ablation re-ab blatiion ddiameter. i metter. ia As a measure transversal diameter measured mea easu ea sur ure off he hheart artt size, i the the llargest arges esst tr tra ansversall he hheart artt di ar iameter t wass m easuredd ffrom rom the pre-ablation angiograms n andd 33-month -mont nthh angi nt gioggrams taken gi tak ken iinn the th he AP projection. proje j cti je tion. Statistical analysis l i Data are expressed in mean ± standard deviation (SD) or as mean (95% confidence interval). A P-value of 0.05 was used as the level of statistical significance. Special software (SPSS Statistics 20, IBM Inc., Armonk, NY) was used for statistical analysis. A repeated measures analysis-ofvariance (ANOVA) of percentage change in diameter was performed to compare the RF and electroporation ablation measurements between the 3 independent and blinded investigators. The effect of ablation technology on the presence of a (part of the) myocardial sleeve in histological sections, corrected for depth of those sections, was investigated in a binary logistic mixed model. The growth in heart size between the acute and the 3- month procedure was investigated with a paired t-test.
6 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
Results None of the electroporation applications resulted in catheter or electrode failure. All shocks resulted in smooth voltage and current waveforms, demonstrating the absence of arcing and barotrauma. The 3-month survival period was uneventful in all animals. Because of technical difficulties, IPV angiography directly post-ablation was not performed in 2 animals. Average RF application time was 12.3 ± 5.9 minutes. In 2 IPVs (animal #2 and #4) more than 15 minutes of RF was necessary to complete the “circle” due to frequent catheter dislodgement. Angiographic analysis Repeated mea measures ANOVA significant between m asuures rees AN A OVA showed no significan OV nt in iinteraction teraction be etwee eeen investigators and methods (p=0.35). directly ablation, p=0.3 p=0 =0.35).. With R =0 RF F ablation, abllation ab on, PV on V diameters diaameeteers decreased decreeasseedd 233 ± 15 15% 5% ddirect irectly ly y af after fteer abl ablat blat bl and remained diameters. ned 7 ± 17% 17% 7 small smaller l er after 3 m ll months, onth thss, when th when comp compared mpared mp ed w with itth pr ith pre-ab pre-ablation bla lati tion ddiameters ti iametters An example off RPV after RF ablation shown Figure Directly after P ddiameter PV iamete teer change h g af ft R fter F ab bla l tion iiss sh hown in in F ig guree 3. 3 D irectlly af afte terr te electroporation ablation, 10%, after ation ati tio abl ablation blati ti PV ddiameters ia te ddecreased ed d 111 1 ± 10 10% % bbutt had had d increased i ed d 119 9 ± 11 11% % af f 3 months, when compared to pre-ablation diameters (Figure 4). Repeated measures ANOVA demonstrated a highly significant difference in long-term (3 months) response between RF and electroporation ablation (26%), p=0.006, 95% CI (9.54;42.01) (Table). The acute change in PV diameter was not statistically analyzed. During aging of the animals from 6 to 9 months, the heart diameter, measured in the anterior-posterior projection, increased 21 ± 7%. (p
The online version of this article, along with updated information and services, is located on the World Wide Web at: http://circep.ahajournals.org/content/early/2014/06/17/CIRCEP.113.001111
Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published in Circulation: Arrhythmia and Electrophysiology can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial Office. Once the online version of the published article for which permission is being requested is located, click Request Permissions in the middle column of the Web page under Services. Further information about this process is available in the Permissions and Rights Question and Answerdocument. Reprints: Information about reprints can be found online at: http://www.lww.com/reprints Subscriptions: Information about subscribing to Circulation: Arrhythmia and Electrophysiology is online at: http://circep.ahajournals.org//subscriptions/
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DOI: 10.1161/CIRCEP.113.001111
Pulmonary Vein Stenosis after Catheter Ablation: Electroporation versus Radiofrequency
Running title: van Driel et al.; PV Stenosis after Ablation: Electroporation vs RF
Vincent J.H.M. van Driel, MD1*; Kars G.E.J. Neven, MD1,2*; Harry van Wessel, BSc1; Bastiaan C. du Pré, MD1; Aryan Vink, MD, PhD3; Pieter A.F.M. Doevendans,, MD,, PhD1; Fred H.M. Wittkampf, PhD1 Department ent ooff Card ent Cardiology, dio i logy, University Medical Center, Cen nte ter, Utrecht, The T e Netherlands; Th N therlands; 2Departm Ne Department m of 3 ologgy, Alfriedd Krupp ol K up Kr pp Hospital, Hosp Ho s it sp ital a , Essen, al Esssen, Germany; Germ many; y De y; Department Depa arttmeent off Pa Path Pathology, th hol olog ogy, og y U University n ve ni v Rhythmology, Medical Medica Me call Center, Centerr, Utrecht, Utrreccht,, The Thee Netherlands. Net ethherllan nds.. * contributed cont n ri nt ribu bute bu t d eq te equally qua uallly
1
Correspondence: V.J.H.M. van Driel, MD University Medical Center Division of Heart and Lungs Department of Cardiology PO Box 85500 3508 GA Utrecht The Netherlands Tel: +31-88-7557269 Fax: +31-88-7555472 E-mail: [email protected]
Journal Subject Codes: [22] Ablation/ICD/surgery
1 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
Abstract: Background - Radiofrequency (RF) ablation inside pulmonary vein (PV) ostia can cause PV stenosis. A novel alternative method of ablation is irreversible electroporation, but the long-term response of PVs to electroporation ablation is unknown. Methods and Results - In 10 six-month old pigs (60-75 kg), the response of PVs to circular electroporation and RF ablation was compared. Ten consecutive non-arcing, 200 joules (J) electroporation applications were delivered 5 to 10 mm inside one of the two main PVs, using a custom deflectable 18 mm circular decapolar catheter. Inside the other PV, circular RF ablation was performed using 30 watts RF applications via an irrigated 4 mm ablation catheter. PV angiograms were made before ablation, immediately after ablation and months d aafter fter ft er 3 mo mont nths nt hs ssurvival. u vii ur PV diameters and heart size were measured. With electroporation ablation, ation, PV ostial osttia iall diameter diam di a e am decreased 11±1 11±10% ±10% ±1 0 directly 0% dir irecctlly after ablation, but had increased incrreased 19±11% aafter in f er 3 months. With RF ft ablation, PV remained V ostial ostial diameter diam meterr decreased dec ecre reas re ased as ed d 223±15% 3±15% 3± % ddirectly irect ctly aafter fterr abl ft ablation bllat atio ionn aand io ndd re rema main ma ined e 77±17% ±17 ±1 ±17% smaller after 21±7% increase during err 3 months m nths mo h than hs tha han pre-ablation pree-ablation e-ab bla lati t onn diameter diaameter despite deesppit ite te a 221 1±7 7% incr creaase in he hheart arrt sizee ddu u aging from months. m 6 too 9 mont n hs. nt Conclusions 200 applications n - In this ns thi his porcine hi porc po r in i e model, mode d l, multiple mullti tipl ipl ple circumferential circumf i ferentia i l 20 00 J electroporation ellecctr t opporationn ap appl p icaa pl inside the PV P ostia ost stia ia do do not not affect afffe f ct c PV PV diameter d amet di am meter ter aatt 33-month -month -m mon onth th h follow-up. fol ollo loww up up.. RF aablation blat bl atio tio i n in iinside side si de P PV V ostia causes considerable PV stenosis directly after ablation, which persists after 3 months.
Key words: catheter ablation, pulmonary vein, pulmonary vein stenosis, radiofrequency, electroporation ablation, radiofrequency ablation
2 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
Introduction Circular electroporation ablation is a novel technique for pulmonary vein (PV) isolation. In a previous animal study, feasibility and safety of circular electroporation for the creation of PV lesions were investigated after a 3-week survival period. One to 4 sequential, non-arcing electroporation applications of 200 joules (J) eliminated PV electrograms in most ostia.1 However, the long-term risk of PV stenosis after electroporation ablation still is unknown. The present animal study was performed to investigate the response of the PV to an excessive number of circular electroporation applications compared too circular RF ablat ablation attio ionn after a 3-month survival period.
Methods All 10 porcine were performed after Animal Experimentation cinee experiments exp xper erim er im imen men e tss w erre pe erf r or orme m d af afte teer prior prio pr ior approval io appr ap prov pr oval ov all ffrom r m th ro thee An A imal im al E Experiment x er xp erim im men e t Committee of the University Guide Care and the h Utrecht Utr trec echt ec htt U n ve ni vers rsit rs ityy and it an in an i ccompliance om mpliaanc ncee wi with t tthe th he G u de ffor ui or C arre an nd Us Usee of Laboratory y Animals Anima Animals. alss.2 E Each Ea ach h aanimal niima mall (6 ((60-75 (60 0-75 75 kkg) g)) wa w was ass in iintubated ntu t ba batteed an aand d an aanesthetized esth es thet th ettiz i ed d aaccording ccor cc o di d ngg tto o standard procedures.1 The porcine left atrium (LA) has 2 PVs suitable for circular catheter ablation: one right or septal PV (RPV) and one inferior PV (IPV) (Figure 1). The RPV enters the LA in close proximity to the atrial septum and fossa ovalis. Before their entrance into the LA, multiple branches merge into a common RPV tubular segment of approximately 10-15 mm in length. The IPV has an approx. 12 mm long tubular segment, and the RPV has an approx. 15 mm long tubular segment after the confluence of a septal and a lateral branch (Figure 1). First, a coronary sinus catheter was inserted via the right jugular vein as fluoroscopic reference for transseptal access. A quadripolar catheter was inserted via the right jugular vein into the right ventricular apex for back-up pacing. Transseptal puncture was performed through 3 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
the right femoral vein. A deflectable 8 French (F) sheath (Agilis™, St. Jude Medical, Minnetonka, MN) facilitated LA catheterization. A temporary screw-in pacing wire (6416, Medtronic Inc., Minneapolis, MN) was inserted via the right femoral vein and fixated in the atrial septum to serve as positional reference for the NavX™ 3D Navigation system (St. Jude Medical, Minnetonka, MN). The LA geometry (including part of the PVs) was reconstructed using the NavX™ system and a standard deflectable quadripolar irrigated ablation catheter with a 4 mm distal electrode (Thermocool™, Biosense Webster Inc., Diamond Bar, CA). Thereafter, angiography of anggio ogr graa both PVs was performed using the antero-posterior (AP), 30 degrees (o) righ right ghht an ght ant anterior teriior ooblique te bliiq bl iq d 300o le left ft aanterior n errio nt ior oblique (LAO) projecti projections tion ti o s for the IPV; on V aand nd AP, 30o cranial andd 30o (RAO) and caudal projections ject je ctions tions for thee RPV. RPV PV V. After Affter te PV angiography, angiograp angio ogrraphy hy,, bo bboth th h PVs PVss were weree alternately altterrnateely ab ablate ablated ed uusing t ora tropo rati tioon or RF ti F energy. y either electroporation Electroporation r i n ab ratio ablation blati tion ion A custom deflectable, ddeflectable efl flecttabl ble 7F 7F, 18 mm circ circular, cii llar decapolar de la el electroporation l tr ati tio catheter thett containing taiiniin 2 mm m ring electrodes separated by 4 mm spacing was introduced through the deflectable sheath in the right femoral vein (Figure 2). This catheter was deployed in the common tubular segment of one of the 2 PVs. Inside the PV, ten cathodal 200 J shocks were delivered between all electrodes of the electroporation catheter and a large indifferent skin electrode (7506, Valley Lab Inc., Boulder, CO) on the shaven lower back. An external, monophasic defibrillator (Lifepak™ 9, Physio-Control Inc., Redmond, WA) was used for energy delivery.1, 3, 4 During each application, current and voltage waveforms were recorded on a dual channel oscilloscope (Tektronix™ TDS 2002B, Beaverton, OR). For each ablation, a different position of the electroporation catheter was chosen to cover the complete tubular segment. Ten applications of 200 J were always
4 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
delivered even when all PV electrograms had already been eliminated. All electroporation catheter positions were stored with the NavX™ system. After each application, the circular electroporation catheter was reconnected to the NavX™ and electrophysiological recording system (Cardiolab™, General Electric Healthcare, Waukesha, WI) to check electrode integrity and to visualize the electrode positions on the NavX™ system. RF ablation The other PV was circumferentially ablated approximately in the middle of the common tubular segment using sequential 30-watt RF applications delivered via the 4 mm irriga irrigated g ted ablation ablaati tion o on catheter and a saline flow rate of 17 ml/min. Maximal electrode temperature eratur uree was was se sett at 442 2oC C. ly,, m maximal a im ax mal a RF RF duration per vein was set seet at at 15 minutes. s PV V isolation was not the Intentionally, objective or or endpoint enndpoint forr electroporation elecctrropor oraationn orr R or RF F ab ablation. blattioon. angi giiog ogra raph ra aphy was pe performe m d direct me ctly ct ly aft ly ftter ablating abl blat bl atiing both at both hP V usi Vs ing tthe he same PV angiography performed directly after PVs using fluoroscopic i setti ic settings inggs as tthe he ppre-ablation re-ab bla l tiion P PV V angi angiograms. gioggrams. gi Follow-up All catheters were removed and the animals were allowed to recover and kept under daily surveillance. After a 3-month survival period, PV angiography was repeated in all animals using the same techniques as described above. Thereafter, the animals were euthanized by exsanguination. Histological investigation After fixation, the common tubular segment of the both PVs, from antrum to approximately the level of branching, was sliced in 3 circular 4-mm long segments and embedded in paraffin. Elastic van Gieson stained sections of the pulmonary side of each of those segments were scanned. Of each section, the percentage of the perimeter showing a myocardial sleeve was
5 Downloaded from http://circep.ahajournals.org/ by guest on August 28, 2014
DOI: 10.1161/CIRCEP.113.001111
measured using ImageJ (National Institutes of Health). The ablated PVs were compared to control PVs from untreated animals. Angiographic analysis Three investigators, blinded for the type of therapy, analyzed all PV angiograms. PV diameters were measured from the PV angiograms taken before ablation, directly after ablation and at 3 months and in all 3 projections. When PV narrowing was obvious at 3 months, PV diameters were always measured at that location. When no narrowing was visible, all measurements were taken in the middle of the common tubular segment. All measurementss were taken at th the he en eendsystolic phase (maximal PV filling and diameter). Diameters measuredd in the the 3 projections projjec ecttio ionns ns were averaged to obtain The o ob obta tain ta in n 1 value value ue for the PV diameter. Th he ppercent ercent change g inn PV P diameter was calculated rel rrelative e ative to the ppre-ablation re-ab blatiion ddiameter. i metter. ia As a measure transversal diameter measured mea easu ea sur ure off he hheart artt size, i the the llargest arges esst tr tra ansversall he hheart artt di ar iameter t wass m easuredd ffrom rom the pre-ablation angiograms n andd 33-month -mont nthh angi nt gioggrams taken gi tak ken iinn the th he AP projection. proje j cti je tion. Statistical analysis l i Data are expressed in mean ± standard deviation (SD) or as mean (95% confidence interval). A P-value of 0.05 was used as the level of statistical significance. Special software (SPSS Statistics 20, IBM Inc., Armonk, NY) was used for statistical analysis. A repeated measures analysis-ofvariance (ANOVA) of percentage change in diameter was performed to compare the RF and electroporation ablation measurements between the 3 independent and blinded investigators. The effect of ablation technology on the presence of a (part of the) myocardial sleeve in histological sections, corrected for depth of those sections, was investigated in a binary logistic mixed model. The growth in heart size between the acute and the 3- month procedure was investigated with a paired t-test.
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DOI: 10.1161/CIRCEP.113.001111
Results None of the electroporation applications resulted in catheter or electrode failure. All shocks resulted in smooth voltage and current waveforms, demonstrating the absence of arcing and barotrauma. The 3-month survival period was uneventful in all animals. Because of technical difficulties, IPV angiography directly post-ablation was not performed in 2 animals. Average RF application time was 12.3 ± 5.9 minutes. In 2 IPVs (animal #2 and #4) more than 15 minutes of RF was necessary to complete the “circle” due to frequent catheter dislodgement. Angiographic analysis Repeated mea measures ANOVA significant between m asuures rees AN A OVA showed no significan OV nt in iinteraction teraction be etwee eeen investigators and methods (p=0.35). directly ablation, p=0.3 p=0 =0.35).. With R =0 RF F ablation, abllation ab on, PV on V diameters diaameeteers decreased decreeasseedd 233 ± 15 15% 5% ddirect irectly ly y af after fteer abl ablat blat bl and remained diameters. ned 7 ± 17% 17% 7 small smaller l er after 3 m ll months, onth thss, when th when comp compared mpared mp ed w with itth pr ith pre-ab pre-ablation bla lati tion ddiameters ti iametters An example off RPV after RF ablation shown Figure Directly after P ddiameter PV iamete teer change h g af ft R fter F ab bla l tion iiss sh hown in in F ig guree 3. 3 D irectlly af afte terr te electroporation ablation, 10%, after ation ati tio abl ablation blati ti PV ddiameters ia te ddecreased ed d 111 1 ± 10 10% % bbutt had had d increased i ed d 119 9 ± 11 11% % af f 3 months, when compared to pre-ablation diameters (Figure 4). Repeated measures ANOVA demonstrated a highly significant difference in long-term (3 months) response between RF and electroporation ablation (26%), p=0.006, 95% CI (9.54;42.01) (Table). The acute change in PV diameter was not statistically analyzed. During aging of the animals from 6 to 9 months, the heart diameter, measured in the anterior-posterior projection, increased 21 ± 7%. (p
