Wide-area antral pulmonary vein and posterior wall isolation by way of segmental nonocclusive applications using a novel radiofrequency ablation balloon

As illustrated in this manuscript, wide-area, antral PVI with concomitant PWI can be safely and effectively performed with the novel HelioStar Introduction Pulmonary vein (PV) isolation (PVI) remains the cornerstone of catheter ablation of atrial fibrillation (AF) and prior studies have shown that wide-area, antral PV ablation is superior to ostial PVI. Yet, an inherent limitation of balloon-based AF ablation strategies is that they frequently yield an ostial-level PVI. Thus, for optimal results and to achieve wide-area, antral PVI, segmental non-PV occlusive applications are commonly required. Such an approach not only can yield an antral-level PVI, but it allows the operator to perform extra-PV ablation, such as posterior wall isolation (PWI). In this manuscript, the authors describe the first reported case of PVI with concomitant PWI performed by means of segmental non-PV occlusive applications using the novel radiofrequency (RF) ablation balloon (HelioStar; Biosense Webster, Irvine, CA), under the direct visualization of 3-D mapping and guided by electrode impedance. (Biosense Webster, Irvine, CA) radiofrequency ablation balloon using a segmental non-PV occlusive approach, guided by 3-D mapping and impedance. Case report A 76-year-old woman with past medical history significant for recurrent symptomatic paroxysmal AF refractory to antiarrhythmic therapy with sotalol and flecainide and multiple cardioversions with early recurrence following the last attempt, in the setting of sleep apnea and pulmonary


Introduction
Pulmonary vein (PV) isolation (PVI) remains the cornerstone of catheter ablation of atrial fibrillation (AF) 1 and prior studies 2,3 have shown that wide-area, antral PV ablation is superior to ostial PVI. Yet, an inherent limitation of balloon-based AF ablation strategies is that they frequently yield an ostial-level PVI. 4 Thus, for optimal results and to achieve wide-area, antral PVI, segmental non-PV occlusive applications are commonly required. Such an approach not only can yield an antral-level PVI, but it allows the operator to perform extra-PV ablation, such as posterior wall isolation (PWI). In this manuscript, the authors describe the first reported case of PVI with concomitant PWI performed by means of segmental non-PV occlusive applications using the novel radiofrequency (RF) ablation balloon (HelioStar; Biosense Webster, Irvine, CA), under the direct visualization of 3-D mapping and guided by electrode impedance.

Case report
A 76-year-old woman with past medical history significant for recurrent symptomatic paroxysmal AF refractory to antiarrhythmic therapy with sotalol and flecainide and multiple cardioversions with early recurrence following the last attempt, in the setting of sleep apnea and pulmonary hypertension, underwent catheter ablation using the novel RF ablation balloon while receiving uninterrupted oral anticoagulation therapy. The procedure was performed under general anesthesia. Bilateral femoral venous access was obtained under ultrasound guidance. A decapolar catheter was inserted inside the coronary sinus for left atrial (LA) recording and pacing and a duodecapolar catheter was inserted in the high right atrium/superior vena cava for right atrial recording and pacing and phrenic nerve (PN) stimulation. After intravenous systemic anticoagulation, a transseptal puncture was performed using the conventional method. Next, the LA and the 4 PVs were mapped by fast anatomical

KEY TEACHING POINTS
An inherent limitation of balloon-based atrial fibrillation ablation strategies is that they frequently yield pulmonary vein (PV) isolation (PVI) at an ostial level.
Thus, to achieve wide-area, antral PVI, segmental non-PV occlusive applications are commonly required.
Such an approach not only can yield an antral-level PVI, but it allows the operator to perform extra-PV ablation, such as posterior wall isolation (PWI).
As illustrated in this manuscript, wide-area, antral PVI with concomitant PWI can be safely and effectively performed with the novel HelioStar (Biosense Webster, Irvine, CA) radiofrequency ablation balloon using a segmental non-PV occlusive approach, guided by 3-D mapping and impedance.
mapping (Carto; Biosense Webster) using a 3F, diagnostic, inner-lumen circular mapping catheter (LassoStar; Biosense Webster), introduced through the RF balloon, which was in turn inserted via a unidirectional 13.5F introducer (Guide-Star; Biosense Webster). The ablation catheter is a compliant, multielectrode, 28-mm RF balloon with 10 irrigated electrodes (4 irrigation ports/electrode) that allows delivery of unipolar RF energy from selected electrodes circumferentially or in a segmental fashion ( Figure 1A). The electrodes are long, spanning 14.5 mm longitudinally along the surface of the balloon, rendering it suitable for non-PV occlusive applications when placed in parallel to the tissue and targeting non-PV structures such as the posterior wall. A multielectrode generator allows the operator to independently control the duration and energy (power) delivered from each of the 10 electrodes ( Figure 1B). Meanwhile, the ablation catheter is fully integrated with the 3-D mapping system (Carto; Biosense Webster), which allows direct visualization of the RF balloon and the inner-lumen circular mapping catheter within the 3-D map. The latter consists of a 3F, 20-mm, fixed-loop, circular catheter with 10 evenly spaced 1-mm electrodes. In addition to allowing for validation of realtime to PVI, it can be used to create a 3-D map by fast anatomical mapping.
In the current patient, all 4 PVs were ablated antrally using the HelioStar RF balloon through a series of non-PV occlusive applications, guided by 3-D mapping. Ablation was performed using 15 watts for 60 seconds from electrodes projecting on the anterior wall and for 30 seconds from those on the posterior wall of the LA. An activated clotting time .350 seconds was maintained during ablation and luminal esophageal temperature monitoring was also performed. Esophageal temperature rises .1 C above baseline were avoided. Additionally, when targeting the right PVs, continuous high-output stimulation (25 mA; 1000 ms) was performed using the duodecapolar catheter inside the superior vena cava. At no time was there loss of right PN pacing capture. Since during ablation PV occlusion was not attempted, no contrast medium injection was required. Instead, the PVs were targeted and segmentally isolated using a nonocclusive strategy ( Figure 1C and 1D). The inner-lumen circular mapping catheter was used as a rail to navigate and control the placement of the RF balloon. Similarly, the LA ridge on the left (the area between the PVs and the appendage) and the carina on the right were targeted using antral, segmental applications ( Figure 2). The approach was primarily guided and greatly facilitated by 3-D mapping, which allows direct visualization of the balloon and the inner-lumen circular mapping catheter in the LA map. During segmental ablation, RF applications were delivered from the electrodes that were in optimal tissue contact. Optimal electrode-tissue contact during nonocclusive applications to the PV antra / posterior wall was assessed by examining the electrode impedance (Supplemental Video). Both the baseline electrode impedance and temperature can be used to differentiate optimal (.95 U, ,30 C) vs suboptimal tissue contact (,80 U, .32 C) and to guide individual electrode selection during RF delivery. Altogether, 13 RF applications and 10 minutes and 9 seconds of ablation time was required to achieve bilateral, wide-area, antral PVI as well as PWI within the region of the PV component 5 -ie, the LA posterior wall region lying between the PVs ( Figure 3). As such, the posterior wall itself was directly ablated and "homogenized" using the balloon as opposed to performing linear ablations. This was further validated by 3-D mapping using a high-density, multielectrode, diagnostic mapping catheter (PentaRay; Biosense Webster), postablation ( Figure 3C). Furthermore, PVI1PWI was also confirmed by performing high-output pacing (.10 mA) extensively, from multiple sites within the area of isolation. At the completion of the procedure, the patient was extubated and discharged to home on the following day. She tolerated the procedure well without any acute or long-term adverse events, including no PN-, vagal-, or esophagusrelated complications. She has maintained sinus rhythm during 14 months of follow-up, off antiarrhythmic therapy. The follow-up consisted of weekly, 60-second, transtelephonic monitoring during the first 6 months, followed by monthly transmissions from 6-12 months and a 24-hour Holter monitor at 12 months, in addition to routine 12-lead electrocardiograms obtained during 1-, 3-, 6-, and 12-month follow-up visits.

Discussion
Several studies have shown a marked benefit associated with an antral-versus an ostial-level PVI. 2,3 In a meta-analysis of 12 studies including 1183 AF patients treated with ostial vs antral PVI, AF recurrence was significantly lower in those treated with a wide, antral approach, with an odds ratio of 0.33 (95% confidence interval: 0.24-0.46; P , .00001). 3 Although prior studies have failed to show a significant advantage with additional substrate-based modification, recent studies 6-8 have found a notable benefit associated with PWI when performed in conjunction with PVI within the region of the PV component, 5 particularly in patients with persistent AF. Although wide, antral PVI and PWI can be successfully performed using point-by-point RF, retrospective 9,10 and prospective randomized trials 11 of PVI1PWI using balloon-based strategies have consistently found this approach to be superior to PVI alone. But this approach requires delivery of segmental non-PV occlusive applications. Aside from eliminating the need for contrast medium use/injection, a non-PV occlusive approach likely also minimizes the risk of PN injury. To elaborate, the reason why PN palsy occurs more commonly with balloon-based AF ablation strategies-be it using the cryoballoon, 12 the laser balloon, 12 or the HelioStar balloon 13 as compared to point-by-point RF 14 -has to do with a more distal placement of balloon catheters inside the right PV ostia during ablation, particularly the right superior PV, which often not only exhibits a larger ostium, but lies closest to the right PN. This also sheds light on the relatively low incidence of PN palsy associated with the laser balloon, 12 which can expand to a larger diameter (up to 38 mm), as compared to the much smaller (23-, 25-, or 28-mm) cryoablation and RF ablation balloons. 12,13,15 Conclusion As illustrated in this initial report, wide-area, antral PVI with concomitant PWI can be safely and effectively performed with the novel HelioStar RF balloon using a segmental non-PV occlusive approach, under direct visualization within