Radiofrequency ablation of paroxysmal atrial fibrillation with the new irrigated multipolar nMARQ ablation catheter: Verification of intracardiac signals with a second circular mapping catheter Raphael Rosso, MD, Amir Halkin, MD, Yoav Michowitz, MD, Bernard Belhassen, MD, Aharon Glick, MD, Sami Viskin, MD From the Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel. BACKGROUND During radiofrequency (RF) ablation of paroxysmal atrial fibrillation, a circular multielectrode recording “lasso” catheter is generally positioned within each pulmonary vein (PV) to determine when pulmonary vein potentials (PVPs) are present and when they have been ablated. The new irrigated multipolar nMARQ circular ablation catheter is positioned within the left atrium to create contiguous circular ablation lines around each PV ostium. OBJECTIVE To determine whether the recordings obtained from the nMARQ catheter position around the PV ostium accurately reproduce the recordings obtained from a lasso catheter positioned within that vein. METHODS In 10 patients undergoing RF ablation of paroxysmal atrial fibrillation, we placed an nMARQ and a lasso catheter around and within each PV, respectively. Recordings obtained from both catheters at baseline and after RF ablation were compared. RESULTS At baseline, recordings of PVPs in both catheters were concordant in 92% of all PVs. However, after RF delivery, the concordance between the nMARQ and lasso recordings was poor.

Introduction Techniques for radiofrequency (RF) ablation of paroxysmal atrial fibrillation (PAF) are based on the seminal observation that this arrhythmia is triggered by ectopic activity primarily originating from the pulmonary veins (PVs).1 To achieve circumferential PV isolation, a circular multielectrode recording catheter is inserted into the lumen of the PV to record PV potentials whereas a unipolar ablation catheter is used for pointby-point ablation around the ostium of that vein.2,3 The end points of the RF ablation procedure include (1) full circumferential ablation around the PV ostium (evidenced by ablation Address reprint requests and correspondence: Dr Raphael Rosso, Department of Cardiology, Tel Aviv Sourasky Medical Center, Weizman 6, Tel Aviv 64239, Israel. E-mail address: [email protected].

1547-5271/$-see front matter B 2014 Heart Rhythm Society. All rights reserved.

The discordant result most commonly observed was disappearance of “PVPs” from the nMARQ catheter with persistence of PVPs in the lasso catheter (12 of 39 [30%]). Conversely, the delivery of RF frequently resulted in fragmented electrograms (pseudo-PVPs) on the nMARQ catheter despite evidence of PV isolation by lasso catheter recordings. CONCLUSIONS The use of an nMARQ catheter alone, as currently recommended, may lead to underestimation and overestimation of the number of RF applications required to achieve PV isolation. KEYWORDS Atrial fibrillation; Radiofrequency ablation; Pulmonary veins ABBREVIATIONS CS ¼ coronary sinus; CT ¼ computed tomographic; LIPV ¼ left inferior pulmonary vein; LSPV ¼ left superior pulmonary vein; PAF ¼ paroxysmal atrial fibrillation; PV ¼ pulmonary vein; PVAC ¼ pulmonary vein ablation catheter; RIPV ¼ right inferior pulmonary vein; RF ¼ radiofrequency; RSPV ¼ right superior pulmonary vein (Heart Rhythm 2014;11:559–565) I 2014 Heart Rhythm Society. All rights reserved.

marks on a mapping system1) and (2) abolition of all spontaneous PV potentials within the vein lumen as recorded by the circular recording catheter.4 However, performance of multiple point ablations around the PV ostium is technically difficult and time-consuming. Moreover, incomplete circumference PV isolation and/or incomplete ablation of all PV potentials, with eventual PV reconnection to the left atrium, are the main reasons for the recurrence of PAF after a seemingly successful ablation.3–6 In order to overcome these inherent limitations of conventional ablation, multipolar circular ablation catheters, such as the nonirrigated multipolar pulmonary vein ablation catheter, “PVAC” (Medtronic, Minneapolis, MN) and, more recently, the irrigated multipolar nMARQ circular ablation catheter (Biosense Webster, Diamond Bar, CA; http://www. biosensewebster.com/nMARQ.php), were introduced into

http://dx.doi.org/10.1016/j.hrthm.2013.12.029

560 clinical practice. The use of multipolar circular ablation catheters is based on the premise that (1) simultaneous ablation from all 10 electrodes of the circular ablation catheter creates a continuous circumferential lesion that will isolate the PV; (2) far-field PV potential activity, as well as abolition of the latter, can be recorded from the circumferential ablation catheter itself. Importantly, and in contrast to conventional techniques, the circumferential ablation catheter is positioned within the left atrium, around the PV ostium, but not within the vein. Furthermore, a rigorous comparison of the ability to record PV potentials from the PV lumen (by the circumferential recording lasso recording catheter) and from the surrounding left atrium (by the circumferential ablation catheter) has never been performed. Therefore, in the present study, we performed simultaneous recording of PV potentials from within the PV and from the surrounding left atrium with the aid of 2 circumferential catheters: a standard lasso recording catheter and the new nMARQ ablation catheter. We compared the recordings obtained from these 2 catheters before, during, and after each RF application.

Methods Ten consecutive patients undergoing RF ablation for PAF by using the double-lasso technique were included (see below). Anticoagulation therapy with warfarin or any of the new oral anticoagulants was replaced by low-molecular-weight heparin 5 or 2 days before the procedure, respectively. A computed tomographic (CT) scan of the left atrium was imported into the CARTO 3 mapping system (Biosense Webster). The ablation procedure was conducted under general anesthesia or conscious sedation. A decapolar catheter was positioned at the coronary sinus (CS), and a quadripolar catheter was positioned at the His bundle level through the right femoral vein. Two 8-F sheaths (SL1, St Jude Medical, St Paul, MN) were introduced into the left atrium with double transseptal puncture performed under fluoroscopic and either transesophageal or intracardiac echocardiography guidance. Upon completion of the first transseptal puncture, intravenous heparin was administered to maintain an activated clotting time of 350 seconds throughout the procedure. A variable-diameter lasso circular mapping catheter (Biosense Webster) was introduced through the SL1 sheath into the PV for electrical mapping. After the second transseptal puncture, the second SL-1 sheath was replaced by a steerable 8.5-F agilis sheath (St Jude Medical). Each of the 4 PVs was imaged by selective angiograms. The nMARQ circular catheter was then introduced into the left atrium through the steerable agilis sheath. The left atrium geometry was created with the nMARQ catheter and then merged with the preacquired CT scan of the left atrium and PVs. The PV antrum was defined according to the angiogram and electrogram analyses of the respective vein. Isolation of each PV was performed at the respective PV antrum by delivery of RF from multiple irrigated electrodes on the nMARQ catheter simultaneously and by using the following settings: catheter irrigation flow rate of

Heart Rhythm, Vol 11, No 4, April 2014 60 mL/min, target temperature of 45ºC, and maximal energy of 25 W for the catheter poles facing the anterior segment of the antrum and of 15 W for the catheter poles near the posterior atrial wall. RF energy was applied at each ablation site for a maximum of 45 seconds. Repeated RF applications were delivered through the nMARQ poles facing the precise lasso electrodes, showing persistent PV potentials until all the local PV electrograms recorded by the lasso catheter disappeared. Isolation of the left-sided PVs was performed during atrial pacing from the distal CS catheter, whereas isolation of the right-sided PVs was performed during sinus rhythm or CS pacing. Importantly, the entire ablation was conducted when the circular recording lasso mapping catheter was positioned distal to the nMARQ catheter within the corresponding PV (Figure 1). The end point of the procedure was the isolation of all PVs, attested by the disappearance of all PV potentials from the lasso catheter within the vein and confirmed by pacing maneuvers. Importantly, a comparison of the PV potentials, recorded from the lasso recording catheter within the PV and from the nMARQ ablation catheter around the PV, was systematically performed for each vein before, during, and after each RF application. However, only the lasso catheter recordings were used to define when PV isolation was achieved by using standard definitions.7–9

Definitions The signals recorded with the lasso catheter at baseline and during ablation were used as “gold standard” for assessing PV isolation. Concordance at baseline: far-field atrial electrograms and PV potentials are simultaneously present or simultaneously absent on both catheters, that is, on the nMARQ catheter positioned at the PV antrum and on the lasso catheter positioned just distal to the nMARQ catheter within the lumen of the same vein. Lack of concordance at baseline: the nMARQ positioned at the antrum fails to show PV potentials seen on the lasso catheter or vice versa. Concordance during RFs existed whenever a significant change in one catheter was accompanied by similar changes in the other catheter. By significant changes, we refer to evidence of PV disconnection (in the form of either disappearance or dissociated activity of PV potentials) or evidence of PV reconnection (reappearance of previously abolished or previously dissociated PV potentials). Overestimation of PV isolation by the nMARQ catheter was thought to have occurred when all PV potentials recorded with the nMARQ catheter had disappeared at a time when PV potentials were still seen on the lasso catheter. Conversely, underestimation of PV isolation by the nMARQ catheter was thought to have occurred when electrograms resembling PV potentials were still seen on the nMARQ catheter after the disappearance of all PV potentials from the lasso catheter.

Results The first patient undergoing RF ablation of PAF with the new nMARQ catheter in our center (on August 15, 2013)

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Figure 1 Fluoroscopic and CARTO map demonstrating the position of the circular (ablation and mapping) catheters. Left panel: Left anterior oblique fluoroscopic view of the left atrium with the lasso catheter positioned within the right superior pulmonary vein (RSPV) and the nMARQ ablation catheter positioned at the antrum (around the ostium) of the same vein. Right panel: 3-Dimensional (3D) reconstruction (anterior view) of the left atrium after merging. Posteroanterior view of 3D reconstruction of the left atrium after merging. The nMARQ catheter is positioned at the pulmonary vein-left atrial junction of the RSPV, while the lasso catheter is positioned more distally within the pulmonary vein. LIPV ¼ left inferior pulmonary vein.

underwent the procedure with a single catheter (as recommended by the manufacturer) and was therefore not included in this series. All 10 subsequent patients underwent the double-lasso technique and are reported here without exception (Table 1). The procedure represented a first RF ablation attempt for 9 patients and redo ablation following PAF recurrence 1 year after an initially successful ablation in one. Altogether, 80% of the procedures were performed by the same operator (R.R.). For these procedures, procedural time and fluoroscopy time gradually decreased from 158 to 60 minutes (109.3 ⫾ 38.4 minutes) and from 45 to 16 minutes (31.3 ⫾ 11.2 minutes), respectively, reflecting a learning curve of the double-lasso technique. The PV diameters, measured at the PV-left atrial junction on the 3-dimensional Table 1

Patient characteristics`

Age (y) Sex: male Symptoms duration (mo) No. of drugs failed Structural heart disease CAD HTN DM Left atrial diameter (mm) LSPV diameter (mm) LIPV diameter (mm) RSPV diameter (mm) RIPV diameter (mm)

59.6 ⫾ 7.4 90% 74 ⫾ 35 1.8 ⫾ 0.8 0% 30% 50% 10% 43.8 ⫾ 2.7 21.3 ⫾ 1.9 17.7 ⫾ 1.6 24 ⫾ 2.2 18.5 ⫾ 3.4

Values are presented as mean ⫾ SD unless stated otherwise. DM ¼ diabetes mellitus; HTN ¼ hypertension; LIPV ¼ left inferior pulmonary vein; LSPV ¼ left superior pulmonary vein; RIPV ¼ right inferior pulmonary vein; RSPV ¼ right superior pulmonary vein.

CT reconstruction of the left atrium, were as follows: left superior pulmonary vein (LSPV), 21.3 ⫾ 1.9; left inferior pulmonary vein (LIPV), 17.7 ⫾ 1.6; right superior pulmonary vein (RSPV), 24 ⫾ 2.2; and right inferior pulmonary vein (RIPV), 18.5 ⫾ 3.4 mm. In 1 patient, a right middle PV of 8 mm diameter was present and it was ablated along with the RSPV. All PVs were eventually isolated in all patients, and there were no complications related to the procedure. All patients remain free of symptomatic arrhythmias in the shortterm (follow-up period 2.5 ⫾ 1 months).

Concordance between recordings for different PVs at baseline LSPV At baseline, there was a 90% concordance between the 2 catheters, with the lasso catheter showing PV potentials in all 10 patients and the nMARQ catheter showing similar potentials in 9 of them. LIPV At baseline, PV potentials were seen on the lasso catheter in 9 (90%) patients; all these patients also showed a PV potential on the nMARQ catheter. In addition, the single patient undergoing a redo procedure had fragmented “PVlike” potentials that were recorded exclusively from the nMARQ catheter while the lasso catheter suggested PV isolation at baseline. Exit block was already present at baseline on both catheters, suggesting that the fragmented potentials observed only on the nMARQ catheter represented atrial tissue ablated at the previous ablation rather than true

562 PV potentials. This vein was considered to be isolated at baseline, and RF was energy not delivered in this vein. Consequently, the total concordance for all LIPVs at baseline was 90%. RSPV All 10 patients showed PV potentials on the lasso catheter, while 9 of them showed PV potentials on the nMARQ catheter (concordance of 90% for the RSPV at baseline). RIPV RIPV recordings showed PV potentials on both catheters in 9 patients and absence of PV potentials on both catheters in the

Heart Rhythm, Vol 11, No 4, April 2014 tenth patient (concordance of 100% for this vein at baseline). Altogether, the concordance between the catheters at baseline was 92.5% (37 of 40 baseline recordings obtained with both catheters in 10 patients were concordant).

Concordance during and after RF delivery In contrast to the good concordance seen at baseline, the concordance between nMARQ and lasso recordings during RF delivery was poor. The discordant result most commonly observed was disappearance of PV potentials from the nMARQ catheter with persistence of PV potentials on the

Figure 2 Simultaneous recordings of intracardiac electrograms obtained with the nMARQ circular ablation catheter and the lasso circular mapping catheter positioned at the antrum and within the pulmonary vein, respectively. Channels I, II, and V1 show the respective surface electrocardiographic leads; n1-2 to n910 show the local electrograms recorded from the 10 electrodes in the nMARQ catheter positioned around the pulmonary vein ostium, whereas L1-2 to L9-10 show the simultaneously recorded electrocardiograms from the lasso catheter positioned within the proximal segment of the same pulmonary vein. At baseline (panel A1), PV potentials are clearly seen on the lasso poles L1-2 and L3-4 (arrows) while the nMARQ recording shows only atrial electrograms. After a first RF application (panel A2), broad PV potentials are evident on nMARQ n2-3 to n4-5 on time with near-field PV potentials on lasso L5-6. After a second RF application (panel A3), there are no PV potentials on the lasso catheter while the nMARQ recording shows fragmented electrograms on n9-10 that can be confused with residual PV potentials. In the left inferior pulmonary vein (LIPV) (panel B), no PV potentials are seen on the lasso catheter at baseline while fragmented electrograms are present on nMARQ n7-8 and n8-9. In the right superior pulmonary vein (RSPV) (panel C), PV potentials are clearly evident at baseline on lasso L1-2 to L3-4 while the nMARQ recording shows only broad atrial electrograms. The vein was successfully isolated after the second RF application (C2), although there are still fragmented signals on the nMARQ recording while the lasso recording shows PV isolation. Shortly thereafter (C3), reconnection of the vein is evident on the lasso L1-2 and L3-4 poles while the nMARQ recording shows no PV potentials. In the right inferior pulmonary vein (RIPV) (panel D), PV potentials are not easily identifiable on either catheter at baseline (panel D1) but are suspected on lasso L1-2 and L3-4. After RF application, PV potentials become clearly evident because of delay in conduction but only on the lasso catheter (arrows in panel D2) they disappear after a second RF application (panel D3).

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Figure 3 Dissociated pulmonary vein (PV) potential activity. Images in panels A and B were recorded after RF ablation of the left inferior pulmonary vein (LIPV) (panel A) and after ablation of the right superior pulmonary vein (RSPV) (panel B). Both patients are in sinus rhythm and demonstrate PV potential automatic activity that is dissociated from the atrial activity. In the patient shown in panel A, the dissociated PV potential activity is evident in the lasso catheter recordings (Ls3-4) but it is not seen on any of the nMARQ recordings. In the patient shown in panel B, the dissociated PV activity is seen in both catheters (arrows).

lasso catheter (12 of 39 [30%] veins). In all these patients, persistence of PV potentials on the lasso catheter led to additional RF delivery until all these lasso PV potentials eventually disappeared. Conversely, delivery of RF frequently (11 of 39 [28%] veins ablated) resulted in fragmentation of the local electrocardiogram recorded along the circular ablation line in the nMARQ catheter. Such fragmented nMARQ electrograms could have been misinterpreted as PV potentials, while PV isolation was evident on the lasso catheter (Figures 2 and 3). Overestimation of PV isolation on the basis of nMARQ catheter recordings was thought to have occurred in 3 of 10 (30%), 3 of 9 (33%), 3 of 10 (30%), and 2 of 10 (20%) of the LSPVs, LIPVs, RSPVs, and RIPVs, respectively. Furthermore, underestimation of PV isolation on the basis of nMARQ catheter recordings was thought to have occurred in 3 of 10 (30%), 4 of 9 (44%), 3 of 10 (30%), and 2 of 10 (20%) of the LSPVs, LIPVs, RSPVs, and RIPVs, respectively (Figure 4).

Discussion Marked technological innovation in the field of circumferential PV isolation has enhanced procedural success rates, shortening procedural duration, and learning curves. The nMARQ catheter is the latest example of such emerging technologies. Use of this circular ablation catheter has several potential advantages compared to standard “point by point” RF. This “all-in-one” catheter permits

simultaneous ablation through 10 irrigated ablation poles, creating a complete circumferential ablation line while it allows mapping the changes in PV electrograms, confirming PV isolation.10,11 The nMARQ catheter is positioned at the PV antrum. In general, even at its smallest available diameter (20 mm), the nMARQ catheter cannot be introduced into the PVs, therefore reducing the risk of PV stenosis. However, by using an nMARQ ablation catheter (or for that matter, using any circular ablation catheter) without concomitant use of a second circular recording catheter, it can be assumed that farfield signals recorded from the left atrium accurately represent PVPs. That assumption, however, has not been tested during clinical use of these catheters in humans.

Main findings Our study demonstrates that, at baseline, the electrograms recorded from the nMARQ catheter at the PV antrum are a good representation of the PV potentials recorded within the proximal segment of the respective vein with a lasso catheter. Specifically, there was a 92.5% correlation between the recordings of the 2 catheters. However, after the delivery of RF energy through the nMARQ catheter, the recordings obtained with the 2 catheters became different, with recordings obtained with the nMARQ catheter frequently showing abolition of local potentials (suggesting PV isolation) while the lasso catheter indistinctly showed that PV connection persisted. The opposite phenomenon was also observed

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Figure 4 Ablation of a right superior pulmonary vein (RSPV). At baseline (panel A), PV potentials are seen on the nMARQ (n2-3 to n9-10) and lasso (L1-2 to L3-4) catheters. After the first RF application (panel B), the nMARQ recordings suggest PV isolation because the spike potentials recordings seen at baseline disappeared and only low-amplitude atrial electrograms are seen on the nMARQ recordings (*); in contrast, PV potentials are clearly present on the lasso catheter (L1-2 and L3-4) even though with delay in conduction (bidirectional arrow). Additional RF application leads to progressive delay in conduction from the atrium to the PV (see longer bidirectional arrow in panel C) until isolation becomes evident on panel D; the spike PV potential seen shortly after the atrial activity in the first sinus beat in panel D (thin arrows) are no longer present in the second sinus beat. Note: Paper speed is 200 mm/s in panels A, B, and C but only 100 mm/s in panel D. Importantly, the nMARQ recordings suggested PV isolation before it actually occurred. Additional RF application was required until the PV activity disappeared from the lasso recordings in panel D.

frequently, with the lasso catheter clearly showing that PV disconnection had occurred while fragmented electrocardiograms continued to be recorded with the nMARQ catheter. Our results suggest that using only an nMARQ catheter— without the use of a lasso catheter for PV recordings—would result in numerous unnecessary RF applications to PVs already isolated and would also result in premature discontinuation of RF delivery for PVs thought to be isolated by nMARQ recordings in approximately one-third of the ablated veins.

Interpretation The high concordant recordings with the 2 catheters observed at baseline suggest that most of the PV potentials recorded with the nMARQ catheter at the PV antrum indeed represent far-field recordings of true PV potentials present in the PV. However, interpretation of the nMARQ recordings during and after local delivery of RF energy becomes challenging. The fractionated “pseudo PV potentials” that locally persist on the nMARQ catheter after the disappearance of all PV potentials from the lasso catheter could well represent recordings from injured left atrial tissue proximal to the ablation line at the time when complete block of conduction distal to the ablation line (toward the PV) has

already been achieved. Interpretation of the opposite phenomenon, that is, abolition of all electrical activity within the circular line of ablation in the antrum (as recorded with the nMARQ catheter) while PV potentials are still recorded within the PV with the lasso catheter, is more difficult. In general, the PV potentials recorded within a PV with the lasso catheter are believed to represent sleeves of atrial endocardial tissue penetrating the PV that are depolarized from proximal to distal by the atrium.12–14 Accordingly, persistence of PV potentials on the lasso catheter must be interpreted as persistence of electrical conduction from the atrium to the endocardial tissue within the PV. One could speculate that persistent PV potentials, when electrical signals are no longer recorded with the nMARQ catheter surrounding the vein, are due to unidentified gaps within the circular ablation line that allow persistence of electrical conduction from the atrium. Indeed, when this phenomenon was observed, repeated delivery of RF, after a slight reposition of the nMARQ ablation catheter, eventually led to the total abolition of PV potentials in all veins of all patients, suggesting that those “unidentified gaps” were eventually ablated. However, animal studies using histology as gold standard show that the nMARQ catheter indeed creates complete and transmural circular ablation lines (Biosense Webster, unpublished data). Alternatively, it is

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possible that the absence of electrical activity within the ablation line despite persistence of conduction across this line (from the atrium to the PV) merely represents a technical problem related to the catheter-tissue interface at the same sites of RF delivery.

565 catheter with real-time verification of PV electrical isolation. Prospective studies using clinical end points are needed to define whether our double-lasso technique will translate into better long-term outcome.

References Study limitations This study has several limitations. (1) In our study, the recordings obtained with the lasso catheter were accepted as gold standard by which the recordings obtained from the nMARQ catheter were graded. Using the nMARQ recordings as gold standard would inevitably lead to opposite conclusions. However, abolition of PV potentials within a vein has been the end point of RF ablation in numerous studies by using standard ablation techniques. (2) One could argue that the complete circumferential RF lesion created around the PV with the nMARQ catheter obviates the need for PV potential recordings. Indeed, Pappone and coworkers15 suggested that anatomically guided ablation was as effective as lasso-guided electric isolation. Nevertheless, the vast majority of operators currently opt for a technique that involves wide area circumferential ablation and is also guided by the signal information obtained from a circular mapping catheter in the PV.3,4,16 The rationale for the use of a circular mapping catheter is to localize the PV ostium (thus ablating proximal to it to reduce the risk of PV stenosis) while simultaneously monitoring the effect of RF ablation on PV-left atrial connections.16–18 Most importantly, the truly important end point of any study on RF ablation of PAF should not be the abolition of PV potentials (as in the present study) but the actual absence of PAF, arrhythmia-related symptoms, and arrhythmia-related complications during long-term follow-up.

Conclusions (1) The use of a circular mapping catheter along with the circular nMARQ ablation catheter is feasible. The doublelasso technique was used safely in 10 consecutive patients and clearly improved the interpretation of the electrograms visualized. (2) The use of an nMARQ catheter alone, as currently recommended, may lead to underestimation and overestimation of the number of RF applications required to achieve PV isolation. (3) For those who consider anatomically guided and electrically guided PV isolation as complementary—rather than competing—techniques, the doublelasso technique proposed here is appealing because it combines the best of 2 worlds: complete circular ablation line through simultaneous RF from irrigated multipolar

1. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339: 659–666. 2. Arentz T, Weber R, Burkle G, et al. Small or large isolation areas around the pulmonary veins for the treatment of atrial fibrillation? Results from a prospective randomized study. Circulation 2007;115:3057–3063. 3. Ouyang F, Bansch D, Ernst S, et al. Complete isolation of left atrium surrounding the pulmonary veins: new insights from the double-lasso technique in paroxysmal atrial fibrillation. Circulation 2004;110:2090–2096. 4. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. J Interv Card Electrophysiol 2012;33:171–257. 5. Takahashi Y, Iesaka Y, Takahashi A, Hiraoka M. Electrical connection between left superior and inferior pulmonary veins in a patient with paroxysmal atrial fibrillation. J Cardiovasc Electrophysiol 2002;13:490–492. 6. Karch MR, Zrenner B, Deisenhofer I, et al. Freedom from atrial tachyarrhythmias after catheter ablation of atrial fibrillation: a randomized comparison between 2 current ablation strategies. Circulation 2005;111:2875–2880. 7. Gerstenfeld EP, Dixit S, Callans D, et al. Utility of exit block for identifying electrical isolation of the pulmonary veins. J Cardiovasc Electrophysiol 2002;13: 971–979. 8. Hocini M, Shah DC, Jais P, et al. Concealed left pulmonary vein potentials unmasked by left atrial stimulation. Pacing Clin Electrophysiol 2000;23: 1832–1835. 9. Shah D, Haissaguerre M, Jais P, et al. Left atrial appendage activity masquerading as pulmonary vein potentials. Circulation 2002;105:2821–2825. 10. Jais PM, Kautzner J, De Chillou C, et al. First experience of PVI using a circular irrigated ablation catheter: acute results and 8 month FU. Heart Rhythm 2013;10: S1–S40. 11. Deneke T, Schade A, Muller P, et al. Acute safety and efficacy of a novel multipolar irrigated radiofrequency ablation catheter for pulmonary vein isolation. J Cardiovasc Electrophysiol 2013 Nov 14. doi: 10.1111/jce.12316. [Epub ahead of print]. 12. Wakili R, Voigt N, Kaab S, Dobrev D, Nattel S. Recent advances in the molecular pathophysiology of atrial fibrillation. J Clin Invest 2011;121:2955–2968. 13. Weiss C, Gocht A, Willems S, Hoffmann M, Risius T, Meinertz T. Impact of the distribution and structure of myocardium in the pulmonary veins for radiofrequency ablation of atrial fibrillation. Pacing Clin Electrophysiol 2002;25: 1352–1356. 14. Ho SY, Sanchez-Quintana D, Cabrera JA, Anderson RH. Anatomy of the left atrium: implications for radiofrequency ablation of atrial fibrillation. J Cardiovasc Electrophysiol 1999;10:1525–1533. 15. Augello G, Vicedomini G, Saviano M, et al. Pulmonary vein isolation after circumferential pulmonary vein ablation: comparison between lasso and threedimensional electroanatomical assessment of complete electrical disconnection. Heart Rhythm 2009;6:1706–1713. 16. Mansour M, Ruskin J, Keane D. Efficacy and safety of segmental ostial versus circumferential extra-ostial pulmonary vein isolation for atrial fibrillation. J Cardiovasc Electrophysiol 2004;15:532–537. 17. Natale A, Raviele A, Arentz T, et al. Venice chart international consensus document on atrial fibrillation ablation. J Cardiovasc Electrophysiol 2007;18: 560–580. 18. Haissaguerre M, Shah DC, Jais P, et al. Electrophysiological breakthroughs from the left atrium to the pulmonary veins. Circulation 2000;102:2463–2465.

Radiofrequency ablation of paroxysmal atrial fibrillation with the new irrigated multipolar nMARQ ablation catheter: verification of intracardiac signals with a second circular mapping catheter.

During radiofrequency (RF) ablation of paroxysmal atrial fibrillation, a circular multielectrode recording "lasso" catheter is generally positioned wi...
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