Pulmonary vein reconnection following cryo-ablation: Mind the “Gap” in the carinae and the left atrial appendage ridge

Pulmonary vein (PV) isolation (PVI) remains cornerstone to ablation of atrial fibrillation (AF). For effective and durable PVI and thus fewer AF recurrences, lesion gaps in transmurality and contiguity responsible for PV reconnection (PVR) could only be addressed when one is cognizant of the potential location and sites where these lesion characteristics may be more prevalent and responsible for PVR. In the case of RF ablation, newer technologies incorporating contact force, time and power with automated monitoring of lesion formation, paying attention to difficult areas (carinae, left superior PV-LAA ridge, right inferior PV) and measuring inter-lesion distance may provide the tools to reduce PVR. On the other hand, the improved thermodynamic characteristics of the latest generation of cryoballloons and operator dexterity to achieve better PV occlusion, may be crucial determinants towards the direction of reduced PVR. Whether newer visualization tools, more vigilant testing during the index ablation procedure in these particular regions, prolonging or adding cryothermic applications, waiting longer to test for entrance and exit block, and/or use of provocative drug testing (isoproterenol/adenosine challenge) might help prevent future PVRs awaits further studies.     

Pulmonary vein isolation with a multielectrode basket catheter

Pulmonary vein (PV) isolation (PVI) techniques have evolved as a curative treatment of atrial fibrillation (AF) since PVI guided by circumferential mapping with a circular catheter was initially proposed. A multielectrode basket catheter (MBC) is also useful for PVI because of some advantages; (1) an MBC provides some information about the PV anatomy on the fluoroscopic image, (2) an MBC can utilize the non-fluoroscopic navigation system, (3) an MBC enables the direct three-dimensional mapping around the PV ostium and antrum, (4) the distal electrodes of the MBC can be used to monitor some activation changes within the PV in real time and thereby indicate the effects of ablation at the ostium and antrum as radiofrequency lesions are created. PVI with an MBC is an effective and safe procedure to cure AF by integrating the PV anatomy and electrophysiology in combination with a non-fluoroscopic three-dimensional navigation system for the ablation catheter.     

Outcome of stand-alone thoracoscopic epicardial left atrial posterior box isolation with bipolar radiofrequency energy for longstanding persistent atrial fibrillation

Introduction

Catheter ablation of longstanding (> 1 year) persistent atrial fibrillation (AF) is associated with poor outcome. This might be due to remodelling and fibrosis formation, mainly located in the posterior left atrial (LA) wall. Therefore, we adopted a thoracoscopic epicardial box isolation of the posterior left atrium using bipolar RF energy with intraoperative testing of conduction block.

Methods and results

Bilateral thoracoscopic box isolation was performed with a bipolar RF clamp. Entrance block was defined as absence of a conducted electrogram within the box, while exit block was confirmed by pacing at 10.0 V/2 ms. Ablation outcome was evaluated after 3, 6, 12 and 24 months with 12-lead ECGs and 24-hour Holter recordings.Twenty-five consecutive patients were included (58 ± 7 years, persistent AF duration 1.8 ± 0.9 years). Entrance block was achieved in all patients and exit block confirmed if sinus rhythm was achieved. After 17 ± 7 months, 76 % of the patients (n = 19) were free of AF recurrence. One patient died within 1 month and was considered an ablation failure. Four patients with AF recurrences regained sinus rhythm with additional catheter ablation or antiarrhythmic drugs.

Conclusions

Treatment of longstanding persistent AF with thoracoscopic epicardial LA posterior box isolation using bipolar RF energy with intraoperative testing of conduction block is feasible and highly effective.     

Pulmonary vein isolation by high intensity focused ultrasound

Pulmonary vein isolation (PVI) using radiofrequency current (RFC) ablation is a potentially curative treatment option for patients with atrial fibrillation (AF). The shortcomings of the RFC technology (technically challenging, long procedure times, complications) steadily kindle the interest in new energy sources and catheter designs. High intensity focused ultrasound (HIFU) has the ability to precisely focus ultrasound waves in a defined area with a high energy density. HIFU balloon catheters (BC) positioned at the PV ostia appear to be an ideal tool to transmit the ablation energy in a circumferential manner to the PV ostia and may therefore bear substantial advantage over conventional ablation catheters in PVI procedures. In clinical trials the HIFU BC has shown promising success rates similar to RFC catheter ablation for PVI in patients with AF. However, procedure times are still long and serious complications have been observed. Therefore, it may be a valuable alternative to the conventional techniques in selected patients but further clinical trials have to be initiated.     

Detection of oesophageal course during left atrial catheter ablation

BackgroundOesophageal changes and injuries were recorded after atrial fibrillation(AF) ablation procedures. The reduction of power in the posterior left atrial(LA) wall(closest to the oesophagus) and the monitoring of temperature in the oesophagus(OE) reduced oesophageal injuries. The intracardiac-echocardiography(ICE) with a Cartosound module provides two-dimensional imaging (2D) to assess detailed cardiac anatomy and its relationship with the OE. The aim of this study was to highlight the safety and feasibility of 3D-reconstruction of the oesophageal course in left atrial catheter ablation(CA) procedures without OE temperature probe or quadripolar catheter to guide ICE OE reconstruction.Methods180 patients(PT) underwent left atrial ablation. AF ablation were 125(69.5%); incisional left atrial tachycardias(IAFL) were 37(20.6%); left atrial tachycardias(LAT) were 19(10.6%). The LA and pulmonary vein anatomies were rendered by traditional electroanatomic mapping(EAM) and merged with an ICE anatomic map. In 109 PT ICE imaging was used to create a geometry of the OE(group A). A quadripolar catheter was used in 71 PT to show OE course associated to ICE(group B).ResultsAblation energy delivery was performed outside the broadest OE anatomy borders. The duration of procedures was longer in group B vs group A Fluoroscopy time was lower in Group A than Group B(Group A 7 ± 3.2 vs 19.2 ± 2.4 min; p < 0.01).ConclusionsOE monitoring with ICE is safe and feasible. Oesophageal anatomy is complex and variable. Many PT will have a broad oesophageal boundary, which increases the risk of untoward thermal injury during posterior LA ablation. ICE with 3D construction of the OE enhances border detection of the OE, and as such, should decrease the risk of oesophageal injury by improving avoidance strategies without intra-oesophageal catheter visualization.     

The usefulness of ventricular pacing during atrial fibrillation ablation in a persistent left superior vena cava: A case report

A 69-year-old woman with palpitations was referred to our hospital for a second session of atrial fibrillation (AF) catheter ablation. She had a history of AF ablation including pulmonary vein (PV) isolation and persistent left superior vena cava (PLSVC) isolation. Electrophysiologic studies showed the veno-atrial connections that had recovered. After PV isolation was performed, AF was induced by atrial premature contraction (APC) from the PLSVC, and AF storm occurred. During PLSVC isolation, AF was not induced by APC from the PLSVC. PLSVC isolation continued during sinus rhythm. The elimination of the PLSVC potential was difficult to confirm because of the far-field potential of the left ventricle. Then, we performed right ventricular pacing. The remaining PLSVC potential was identified. After that, the PLSVC isolation was successful during right ventricular pacing. Complications were not observed. The patient had no recurrence of AF thereafter.     

Improved durable pulmonary vein isolation with shorter procedure times and lower energy levels using RF ablation with ablation index and a stringent lesion contiguity

BackgroundThe single procedure success rates of durable pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) varies between 80 and 90%. Ablation index, incorporating contact force, stability, time and power is a more profound parameter of significant lesion size and has been established. Equally important is a stringent contiguity of the lesion set.Methods and resultsA total number of 100 consecutive patients undergoing de-novo catheter ablation for paroxysmal atrial fibrillation (PAF) were analyzed between 2016 and 2019. In the first 50 patients (group A) PVI was performed using a surround flow, contact force catheter (Biosense Webster Thermocool STSF, Biosense Webster, USA) with a drag-and-ablate technique to encircle the PVs. In the following 50 patients (group B), PVI was performed using ablation index and a stringent lesion contiguity with an interlesion distance (ILD) of <5 mm. The baseline characteristics showed no significant differences between both groups. During a mean follow-up of 18 ± 3 months after a single procedure, 36 (72%) patients of group A were free of arrhythmia recurrence versus 43 (86%) patients in group B (p = 0.047). A total of 14 patients (group A: 10 (20%), group B: 4 (8%); underwent a redo-procedure. 7 patients of group A (14%) and 2 patients of group B (4%) showed recovered veins. In 3 patients of group A and 2 patients of group B the PVs were durably isolated. In these patients persistent AF recurrence was caused by extra-PV AF sources. Four patients of group A and three patients of group B had continued paroxysmal or persistent AF but did not undergo redo-procedure. With regard to the procedural data, the procedure time, the total energy and the fluoroscopy time were significantly lower in group B (AI and ILD <5 mm) (128.86 ± 18.19 versus 115.35 ± 15.38; p < 0.05; 1619.16 ± 988.56 versus 1186.26 ± 756.34; p < 0.05; 11.49 ± 3.20 versus 9.66 ± 3.86; p = 0.04). Both procedures were performed with a low number of complications, no pericardial effusion was seen in either group.ConclusionsPVI using ablation index in combination with a stringent lesion contiguity improves clinical outcome after first-time PVI with lower PVI recovery, shorter procedure times, lower total energy and shorter fluoroscopy times and therefore, is more efficient.     

Safety and feasibility of atrial fibrillation ablation using Amigo® system versus manual approach: A pilot study

Background

The Amigo^® Remote Catheter System is a relatively new robotic system for catheter navigation. This study compared feasibility and safety using Amigo (RCM) versus manual catheter manipulation (MCM) to treat paroxysmal atrial fibrillation (PAF). Contact force (CF) and force-time integral (FTI) values obtained during pulmonary vein isolation (PVI) ablation were compared.

The ABC of a Simple Method for Pulmonary Vein Angiography

Catheter-directed intervention to treat atrial fibrillation (AF) is becoming widely accepted procedure in current clinical practice. For assessment of pulmonary vein (PV) anatomy, angiography of left atrium (LA) and/or PV is often performed. We present a new, simple angiographic method for PVs and LA opacification using SL1 sheath. Total of 100 patients in our clinic underwent this procedure. In all of the cases good angiographic results were achieved. No immediate or late complications related to this procedure were observed.     

A linear ablating system in the left and right atrium: feasibility, catheter performance and clinical results

IntroductionWe describe the use of a ablating system to compartmentalise and regionally isolate the atria in paroxysmal and persistent atrial fibrillation (AF).Methods40 patients were studied, 25 paroxysmal AF and 14 persistent AF. One patient enrolled was later found to be in left atrial flutter and was excluded. The Cardima Revelation® TX catheter system with Intellitemp® Radiofrequency (RF) energy control device and a Medtronic Atakar® RF generator were used to place wide area circumferential ablations to achieve conduction block into the left and right sided pulmonary veins. Roof lines and mitral isthmus lines were also performed. In patients with persistent AF and in repeat procedures, right atrial compartmentalisation was performed with an anterior superior vena cava (SVC) to inferior vena cava (IVC) line and a septal SVC to IVC line.ResultsAt 6 months, 18 of the 39 patients were asymptomatic, 10 had improved symptoms and 22 were in sinus rhythm. In the paroxysmal group, 11 were asymptomatic, 7 had improved symptoms and 16 (64%) were in sinus rhythm. In the persistent group, 7 were asymptomatic, 3 had improved symptoms and 6 (43%) were in sinus rhythm. The total group AF burden was 37.8 ± 5.4 hrs pre-procedure and 23.1 ± 5.1 hrs at 6 months post procedure. Mean temperature, impedance and power recorded at each pole demonstrated effective power delivery at all poles. No catheter charring was observed, complication rates were comparable to standard AF ablation technique.ConclusionLinear ablation in the left and right atria to mimic Cox’s Maze is feasible and safe using this ablating system.     

肺静脉口弧形指数与房颤消融术后复发的关系

目的:探讨肺静脉口弧形指数与心房颤动(房颤)导管消融术后复发的关系。方法:选取2008年2月至2011年3月在我院接受导管消融术的房颤患者120例,所有患者于术前3日内利用多排CT行左心房及肺静脉造影,并进行图像的三维重建。测量每条肺静脉前后径及上下径,并计算弧形指数(肺静脉前后径/肺静脉上下径)以描述肺静脉口形态。行射频消融治疗的房颤病人全部达消融终点,术后随访超过3个月,根据患者房性快速性心律失常(房颤、房扑或房速)的发生情况,将其分为治愈组和复发组,进行统计分析。结果:由弧形指数分析,四支肺静脉开口形态存在统计学差异(P0.05);房颤消融术后,53例病人复发。房颤消融术后复发患者的LIPV弧形指数与治愈者不同,差异有显著性(P0.05);两组患者的左上肺静脉(Left Superior Pulmonary Vein,LSPV),右上肺静脉(Right Superior Pulmonary Vein,RSPV),右肺下静脉(Right Inferior Pulmonary Vein,RIPV),的弧形指数比较差异不明显(P0.05)。结论:左下肺静脉形态的不一致性与房颤导管消融术复发有关。     

Three-dimensional computed tomography overlay for pulmonary vein antrum isolation: Follow-up and clinical outcomes

Background

To facilitate the creation of circumferential lines in pulmonary vein (PV) antrum isolation, three-dimensional (3D) navigation systems are used widely. Alternatively, 3D reconstructions of the left atrium (LA) can be superimposed directly on fluoroscopy to guide ablation catheters and to mark ablation sites.

Methods

In 71 atrial fibrillation patients circumferential PV ablation was performed. 3D reconstructions of the LA were derived from contrast cardiac-computed tomography and circumferential PV isolation was performed. In subsequent ablation procedures, veins were re-isolated, and defragmentation or linear lesions were performed if necessary.

Results

Adequate 3D reconstructions were formed and registered to fluoroscopy in all patients. All veins, except 2 in one single patient, could be isolated, resulting in freedom of AF in 45 patients (63?%). In 19 patients a second procedure was performed, in which 2.7?±?1.1 PV per patient were re-isolated; in 3 patients a third procedure was performed. After follow-up of 15?±?8?months, 51 (91?%) of patients with paroxysmal and 10 (67?%) with persistent AF were free of AF.

Conclusions

The results of 3D overlay for circumferential PV isolation are good, although the reconduction rate and need for subsequent ablations remains high, and the outcomes of this technique appear to be equivalent to other mapping techniques.     

A modified regimen of extracorporeal cardiac shock wave therapy for treatment of coronary artery disease

Background

Radiofrequency catheter ablation of atrial fibrillation (AF) has been proved to be effective and to prevent progressive left atrial (LA) remodeling. Cryoballoon catheter ablation (CCA), using a different energy source, was developed to simplify the ablation procedure. Our hypothesis was that successful CCA can also prevent progressive LA remodeling.

Methods

36 patients selected for their first CCA because of nonvalvular paroxysmal AF had echocardiography before and 3, 6 and 12 months after CCA. LA diameters, volumes (LAV) and LA volume index (LAVI) were evaluated. LA function was assessed by: early diastolic velocities of the mitral annulus (Aa_sept, Aa_lat), LA filling fraction (LAFF), LA emptying fraction (LAEF) and the systolic fraction of pulmonary venous flow (PVSF). Detailed left ventricular diastolic function assessment was also performed.

Results

Excluding recurrences in the first 3-month blanking period, the clinical success rate was 64%. During one-year of follow-up, recurrent atrial arrhythmia was found in 21 patients (58%). In the recurrent group at 12 months after ablation, minimal LAV (38 ± 19 to 44 ± 20 ml; p < 0.05), maximal LAV (73 ± 23 to 81 ± 24 ml; p < 0.05), LAVI (35 ± 10 to 39 ± 11 ml/m²; p = 0.01) and the maximal LA longitudinal diameter (55 ± 5 to 59 ± 6 mm; p < 0.01) had all increased. PVSF (58 ± 9 to 50 ± 10%; p = 0.01) and LAFF (36 ± 7 to 33 ± 8%; p = 0.03) had decreased. In contrast, after successful cryoballoon ablation LA size had not increased and LA function had not declined. In the recurrent group LAEF was significantly lower at baseline and at follow-up visits.

Conclusions

In patients whose paroxysmal atrial fibrillation recurred within one year after cryoballoon catheter ablation left atrial size had increased and left atrial function had declined. In contrast, successful cryoballoon catheter ablation prevented progressive left atrial remodeling.     

Anatomic Twist to a Straightforward Ablation

Atrioventricular (AV) junction ablation for treatment of refractory atrial fibrillation is a well defined, standardized procedure and the simplest of commonly performed radiofrequency ablations in the field of cardiac electrophysiology. We report successful AV junction ablation using an inferior approach in a case of inferior vena cava interruption. Inability during the procedure to initially pass the ablation catheter into the right ventricle, combined with low amplitude electrograms, led to suspicion of an anatomic abnormality. This was determined to be a heterotaxy syndrome with inferior vena cava interruption and azygos continuation, draining in turn into the superior vena cava. Advancing Schwartz right 0 (SRO) sheath through the venous abnormality into the right atrium allowed adequate catheter stability to successfully induce complete AV block with radiofrequency energy.     

Epicardial Atrial Ablation Using a Novel Articulated Robotic Medical Probe Via a Percutaneous Subxiphoid Approach

OBJECTIVE: Minimally invasive epicardial atrial ablation to cure atrial fibrillation through the use of a percutaneous subxiphoid approach currently has a lack of dedicated technology for intrapericardial navigation around the beating heart. We have developed a novel articulated robotic medical probe and performed preliminary experiments in a porcine preparation. METHODS: In five large, healthy pigs, the teleoperated robotic system was introduced inside the pericardial space through a percutaneous subxiphoid approach. Secondary visualization of the left atrium and left atrial appendage was achieved with the use of a 5-mm scope inserted through a left thoracic port. The operator actively controlled the path of the robot by using a master manipulator. The catheter, with an irrigated radiofrequency tip, was guided through the working port of the robot to achieve epicardial ablation of the left atrium. RESULTS: Access to the pericardial space and progression around the left atrium was successful in all cases, with no interference with the beating heart such as a fatal arrhythmia, unexpected bleeding, and hypotension. Epicardial ablation was successfully performed in all five cases. No adverse hemodynamic or electrophysiological events were noted during the trials. When the animals were killed, there was no visually detected injury on the surrounding mediastinal structures caused by ablation. Transmural ablation was confirmed by histopathology of the left atrium. CONCLUSIONS: We have developed a dedicated articulated robotic medical probe and successfully performed epicardial left atrial radiofrequency ablation. Based on the feedback from these preliminary experiments, the radius of curvature and proper visualization of the device are being improved in the next generation prototype.     

High-density activation map of atrial tachycardia within left atrial appendage

Identification of the critical isthmus of the reentrant tachycardia is essential to maximize the effect of catheter ablation (CA) and to minimize the myocardial injury of CA. An 81-year-old woman presented recurrent palpitations after CA of atrial fibrillation (AF) and atrial tachycardia (AT). She had moderate aortic valve stenosis and coronary artery disease. She had received a pulmonary vein isolation, left atrial (LA) posterior wall isolation, and LA anterior linear ablation for atrial fibrillation 1 year prior. At the start of the procedure, she was in sinus rhythm. Atrial burst pacing induced an AT (230msec). High-density mapping revealed a figure-of-eight activation pattern within the LA appendage (LAA), accounting for 99% of the tachycardia cycle length. The critical isthmus was identified at the mid LAA and the local electrogram of the critical isthmus was not fractionated. A single radiofrequency application at the critical isthmus of the AT, terminated the AT. She was free from any ATs for 28 months.Radiofrequency ablation of the localized reentrant AT was usually performed targeting long fractionated electrograms. In our case, the local electrogram at the critical isthmus was not fragmented compared with the LAA distal part. Long fractionated electrograms were recorded at a more distal part of the LAA than the common isthmus and we could avoid the potential risk of a perforation. A recent developed 3-dimensional electro-anatomical mapping system can identify the critical isthmus and allow us to select a new therapeutic strategy for a critical isthmus ablation of an AT within the LAA.     

Measurement of Left Atrial Pressure is a Good Predictor of Freedom From Atrial Fibrillation

Background

It is suggested that an elevated left atrial pressure (LAP) promotes ectopic beats emanating in the pulmonary veins (PVs) and that LAP might be a marker for structural remodeling. This study aimed to identify if the quantification of LAP correlates with structural changes of the LA and may therefore be associated with outcomes following pulmonary vein isolation (PVI).

Methods

We analysed data from 120 patients, referred to PVI due to drug-refractory atrial fibrillation (AF) (age 63±8; 57% men). The maximum (mLAP) and mean LAP (meLAP) were measured after transseptal puncture.

Results and Conclusions

Within a mean follow-up of 303±95 days, 60% of the patients maintained in sinus rhythm after the initial procedure and 78% after repeated PVI. Performing univariate Cox-regression analysis, type of AF, LA-volume (LAV), mLAP and the meLAP were significant predictors of recurrence after PVI (p=0.03; p=0.001; p=0.01). In multivariate analysis mLAP>18mmHg, LAV>100 ml and the presence of persistent AF were significant predictors (p=0.001; p=0.019; p=0.017). The mLAP >18 mmHg was associated with a hazard ratio of 3.8. Analyzing receiver-operator characteristics, the area under the curve for mLAP was 0.75 (p<0.01). mLAP >18 mmHg predicts recurrence with a sensitivity of 77 % and specificity of 60 %. There was a linear correlation between the LAV from MDCT and mLAP (p = 0.01, R2 = 0.61). The mLAP measured invasively displays a significant predictor for AF recurrence after PVI. There is a good correlation between LAP and LAV and both factors may be useful to quantify LA remodeling.     

Exchanging Catheters Over a Single Transseptal Sheath During Left Atrial Ablation is Associated with a Higher Risk for Silent Cerebral Events

Background

Silent cerebral events (SCE) have been identified on magnetic resonance imaging (MRI) in asymptomatic patients after atrial fibrillation (AF) ablation. Procedural determinants influencing the risk for SCE still remain unclear.

Objective

Comparing the risk for SCE depending on exchanges of catheters (ExCath) over a single transseptal sheath.

Methods

88 Patients undergoing pulmonary vein isolation (PVI) only ablation using either single-tip or balloon-based technique underwent pre- and post-ablation cerebral MRI. Ablations were either performed with double transseptal access and without exchanging catheters over the transseptal sheaths (group 1: no ExCath) or after a single transseptal access and exchanges of therapeutic and diagnostic catheters (group 2: ExCath). Differences in regard to SCE rates were analyzed. Multivariate analysis was performed to identify factors related to the risk for SCE.

Results

Included patients underwent PVI using single tip irrigated radiofrequency in 41, endoscopic laser balloon in 27 and cryoballoon in 20 cases. Overall SCE were identified in 23 (26%) patients. In group 1 (no ExCath; N=46) 6 patients (13%) and in group 2 (N=42) 17 patients (40%) had documented SCE (p=0.007). The applied ablation technology did not affect SCE rate. In multivariate analysis age (OR 1.1, p=0.03) and catheter exchanges over a single transseptal sheath (OR 12.1, p=0.007) were the only independent predictors of a higher risk for SCE.

Conclusions

Exchanging catheters over a single transseptal access to perform left atrial ablation is associated with a significantly higher incidence of SCE compared to an ablation technique using different transseptal accesses for therapeutic and diagnostic catheters.     

Pulmonary vein isolation: do all roads lead to Rome?

Pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF) appears to be here to stay. In just a few years since the landmark publications by Haissaguerre and Pappone, countless variations on the theme of ostial or antral PVI, with or without additional lines or point lesions, have been published. The procedure has found its way into daily practice and international guidelines, and is currently the most performed ablation in the Netherlands.     

What are the post-ablation insular residual electrograms in the posterior left pulmonary veins electrically connected to?

A 67-year-old man underwent a third ablation procedure for a recurrent atrial tachycardia (AT) after an extensive pulmonary vein (PV) isolation, linear ablation along the left atrial (LA) roof and posterolateral mitral isthmus (MI), and defragmentation of persistent atrial fibrillation and an induced perimitral AT. High-resolution mapping during the clinical AT using the Rhythmia system (Boston Scientific) suggested that the AT was a ridge-related reentrant AT and exhibited a reconnection of the left PVs (LPVs). The residual electrograms in the posterior LPVs were surrounded by endocardial scar, which was like an island consisting of residual LPV electrograms. Retrograde venography of the vein of Marshall (VOM) demonstrated that the VOM reached the posterior left superior PV through the ridge between the LA appendage and left inferior PV and then the LPV carina. An ethanol infusion into the VOM resulted in a simultaneous AT termination and complete electrical isolation of the LPVs, that is, the disappearance of the residual LPV electrograms. The insular residual LPV electrograms in the present case did not appear to be endocardially connected to the LA, because the LPV electrograms were surrounded by endocardial scar and there was a large time gap between the earliest activation in the posterior LPVs and activation in the surrounding area. The VOM course on the venography and elimination of the residual LPV electrograms with an ethanol infusion into the VOM suggested that the insular residual LPV electrograms were electrically connected to the posterolateral LA via the VOM and its branches.