Importance of the relative epicardial connection locations and right-sided pulmonary vein isolation line for successful pulmonary vein isolation.

INTRODUCTION: The presence of an epicardial connection (EC) decreases the success rate of pulmonary vein isolation (PVI); however, the effect of designing isolation lines has not been evaluated. We sought to clarify the effects of designing an anterior line for right-sided PVI considering the presence and location of the EC. METHODS: Seventy-four consecutive patients who underwent initial catheter ablation for atrial fibrillation were retrospectively included in this study. The presence of the EC was determined by the left atrial (LA) activation map during right atrial pacing, and patients were divided into EC-positive (n = 23, 31%) and EC-negative (n = 51, 69%) groups. EC-positive patients were further subdivided based on the EC location: on-the-line group, (EC on the PVI line, n = 11); inside-line group (EC on the pulmonary vein [PV] side, n = 10); and outside-line group (EC on the LA side, n = 2). The PVI parameters were compared among the three groups. RESULTS: The success rates of the first-pass isolation were comparable between the EC-negative and EC-positive groups (70.6% vs. 60.9%, ns), but the success rate was significantly higher in the on-the-line group than in the inside-line group (91% vs. 20%, p = 0.002). First-pass isolation was successful in both patients in the outside-line group. Additional carina ablation was required only in the inside-line group. CONCLUSIONS: The association between the EC site and the right-sided PV anterior isolation line affected the success rate of first-pass isolation. For successful right-sided PVI, it is important to consider the EC site when designing the PVI line.

Unidirectional conduction characterizing epicardial connections in patients with atrial tachyarrhythmias.

INTRODUCTION: Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. METHODS: This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. RESULTS: Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up. CONCLUSION: A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

Detection of a unidirectional epicardial connection between the right-sided pulmonary venous carina and the right atrium by pacing from a high-density mapping catheter.

We report a case of recurring, persistent atrial fibrillation (AF) in a patient with a unidirectional epicardial connection (EC) between the right-sided pulmonary venous (PV) carina and the right atrium detected using a high-density mapping catheter with a steerable introducer support, but not a conventional circular mapping catheter. This unidirectional EC could be steadily abolished by a radiofrequency delivery. Finally, we were able to successfully achieve complete PV antrum isolation. Thereafter, he has remained well without any AF.

Distinct propagation patterns of right pulmonary veins through multiple epicardial connections during right atrial pacing and sinus rhythm.

A 47-year-old man with symptomatic paroxysmal atrial fibrillation (AF) underwent AF ablation. Activation maps during right atrial pacing and sinus rhythm before the ablation revealed distinctive left atrial (LA) propagations with multiple LA breakthrough sites via epicardial connections. A wide area circumferential ablation was not able to achieve a right pulmonary vein (RPV) isolation and required an inner PV ablation to isolate the RPV. Activation maps during different rhythms before the ablation may be helpful to unmask multiple epicardial connections between the RPV and right atrium.

Epicardial Connections After a Conventional Pulmonary Vein Antrum Isolation in Patients With Atrial Fibrillation.

BACKGROUND: The existence of epicardial connection(s) (ECs) between the pulmonary veins (PVs) and atrium may hinder establishing a complete PV antrum isolation (AI) (PVAI) in patients with atrial fibrillation (AF). Thus, the purpose of this study was to determine the prevalence and location of ECs inside the conventional PVAI lines.Methods and Results: Three-hundred consecutive patients with non-valvular AF were evaluated. This study revealed that: (1) the prevalence of patients with ECs and the number of ECs per patient between the PVs and atrium became significantly greater, respectively, in accordance with the progression of paroxysmal to long-lasting AF and left atrial enlargement; (2) some ECs were located at sites far distal to the PVAI lines; (3) 25% of ECs could be detected only by high-density mapping catheters, but not by conventional circular mapping catheters; (4) a B-type natriuretic peptide (BNP) level of 176.6pg/mL and left atrial volume (LAV) of 129.0 mL may be important predictors of the presence of ECs; and (5) the rate of conduction of ECs from the right PVs was dominantly to the atrium and His-bundle, and that from the left PVs to the coronary sinus was most dominant. CONCLUSIONS: The PVAI may not be completed by using only a conventional PVAI method, and additional EC ablation inside the PVAI lines detected using high-density mapping may be able to achieve a more complete PVAI.

Characteristics of macroreentrant atrial tachycardias using an anatomical bypass: Pseudo-focal atrial tachycardia case series.

INTRODUCTION: Human atria comprise distinct layers. One layer can bypass another, and lead to a downstream centrifugal propagation at their interface. We sought to characterize anatomical substrates, electrophysiological properties, and ablation outcomes of "pseudo-focal" atrial tachycardias (ATs), defined as macroreentrant ATs mimicking focal ATs. METHODS AND RESULTS: We retrospectively analyzed left atrial ATs showing centrifugal propagation with postpacing intervals (PPIs) after entrainment pacing suggestive of a macroreentrant mechanism. A total of 22 patients had pseudo-focal ATs consisting of 15 perimitral and 7 roof-dependent flutters. A low-voltage area was consistently found at the collision site and colocalized with distinct anatomical structures like the: (1) coronary sinus-great cardiac vein bundle (27%), (2) vein of Marshall bundle (18%), (3) Bachmann bundle (27%), (4) septopulmonary bundle (18%), and (5) fossa ovalis (9%). The mean missing tachycardia cycle length (TCL) was 65 ± 31 ms (22%) on the endocardial activation map. PPI was 0 [0-15] ms and 0 [0-21] ms longer than TCL at the breakthrough site and the opposite site, respectively. While feasible in 21 pseudo-focal ATs (95%), termination was better achieved by blocking the anatomical isthmus than ablating the breakthrough site [20/21 (95%) vs. 1/5 (20%); p < .001]. CONCLUSION: Perimitral and roof-dependent flutters with centrifugal propagation are favored by a low-voltage area located at well-identified anatomical structures. Comprehensive entrainment pacing maneuvers are crucial to distinguish pseudo-focal ATs from true focal ATs. Blocking the anatomical isthmus is a better therapeutic option than ablating the breakthrough site.

The incidence and location of epicardial connections in the era of contact force guided ablation for pulmonary vein isolation.

BACKGROUND: The effects of epicardial connections (ECs) involving pulmonary veins (PVs) in atrial fibrillation (AF) ablation have been revealed recently. However, no systematic approaches to identify and ablate the ECs were established. METHODS: Patients with AF undergoing radiofrequency (RF) catheter ablation were retrospectively analyzed. ECs were identified when (1) PV isolation (PVI) cannot be achieved after first-pass isolation; (2) PVI was still absent although the conduction gap was detected and ablated; (3) the earliest activation area (EAA) was revealed located within the PV antrum distant from the initial ablation line using high-density mapping (HDM) technique; (4) focal ablation at the EAA was effective to achieve PVI. Relevant pacing maneuvers were performed to elucidate ECs' bidirectional conduction. RESULTS: Overall, 36 ECs were identified and ablated in 35/597 (5.86%) patients. Among the 35 patients with ECs, at least one PV insertion of ECs was located at the carina region. The most common pattern was a single breakthrough in 31 (88.6%) patients, followed by multiple breakthroughs in 3 and wide breakthroughs in 1. The median distance from EAA to the initial ablation line was 10.0 mm. The average number of RF energy delivery was 1.75 ± 1.00, and single RF delivery was adequate in 16/36 (44.4%) patients. Continuous potentials were present at the EAA in 9/34 (26.5%) patients. CONCLUSION: ECs were confirmed and ablated successfully in 5.86% (35/597) AF patients using HDM. PV insertions of ECs were mainly located at the carina region. Continuous potentials might assist in the prediction of ECs.

A simple pacing maneuver to unmask an epicardial connection involving the right-sided pulmonary veins.

INTRODUCTION: An epicardial connection (EC) between the right-sided pulmonary venous (PV) carina and right atrium (RA) is one of the mechanisms for which carinal ablation is required for right-sided PV isolation. The purpose of the study was to devise a simple pacing maneuver to differentiate an EC from a residual conduction gap on the antral ablation line during radiofrequency catheter ablation. METHODS AND RESULTS: This study included 133 consecutive patients. After one round of ablation, electrograms at the posterior antrum outside the ablation line were recorded during sinus rhythm (SR) and coronary sinus (CS) pacing, and intervals between the antral and PV potentials were measured in each rhythm. The ΔintervalSR-CS was calculated as the difference between the interval during SR and that during CS pacing. Presence of an EC was confirmed by observation of a RA posterior wall breakthrough during right-sided PV pacing, which was then targeted for ablation. Patients with nonachievement of first-pass isolation (N = 35) and with PV reconnection during the procedure (N = 9) were classified into the EC-group (N = 20) and gap-group (N=24), respectively. The prevalence of carina breakthrough during SR was higher in the EC-group than the gap-group (18 [95%] vs. 1 [4%] patients, p < .0001). The ΔintervalSR-CS was larger in the EC-group versus gap-group (71 [interquartile range, 57-97] vs. 6 [2-9] ms, p < .0001). In all patients with an EC, RA ablation resulted in delay (32 [20-40] ms) (N = 15) or elimination of PV potentials (N = 5). CONCLUSION: An EC can be efficiently discriminated from a conduction gap by a simple pacing maneuver.

Multiple epicardial connections during extensive pulmonary vein isolation.

A 76-year-old male underwent a pulmonary vein isolation (PVI) of atrial fibrillation. The first-pass encirclement did not isolate the left superior PV (LSPV). High-resolution activation mapping during LSPV pacing identified the earliest activation site (EAS) on the left atrial (LA) roof outside the PVI line. A radiofrequency application on the roof isolated the LSPV. Thereafter, an LSPV reconnection occurred. Second activation mapping during LSPV pacing identified the EAS at the bottom of the ridge outside the PVI line. Radiofrequency applications targeting the EAS eliminated the LSPV reconnection. The multiple residual connections may be associated with spared epicardial PV-LA connections.

Detection of Epicardial Connection Through Intercaval Bundle Involving Right Pulmonary Veins After Ipsilateral Circumferential Ablation by Intra-Atrial Activation Sequence Pacing From the Right Pulmonary Vein.

BACKGROUND: An epicardial connection (EC) through the intercaval bundle (EC-ICB) between the right pulmonary vein (RPV) and right atrium (RA) is one of the reasons for the need for carina ablation for PV isolation and may reduce the acute and chronic success of PV isolation. We evaluated the intra-atrial activation sequence during RPV pacing after failure of ipsilateral RPV isolation and sought to identify specific conduction patterns in the presence of EC-ICB. METHODS AND RESULTS: This study included 223 consecutive patients who underwent initial catheter ablation of atrial fibrillation. If the RPV was not isolated using circumferential ablation or reconnected during the waiting period, an exit map was created during mid-RPV carina pacing. If the earliest site on the exit map was the RA, the patient was classified into the EC-ICB group. The exit map, intra-atrial activation sequence, and RPV-high RA time were evaluated. First-pass isolation of the RPV was not achieved in 36 patients (16.1%), and 22 patients (9.9%) showed reconnection. Twelve and 28 patients were classified into the EC-ICB and non-EC-ICB groups, respectively, after excluding those with multiple ablation lesion sets or incomplete mapping. The intra-atrial activation sequence showed different patterns between the 2 groups. The RPV-high RA time was significantly shorter in the EC-ICB than in the non-EC-ICB group (69.2±15.2 versus 148.6±51.2 ms; P<0.001), and RPV-high RA time<89.0 ms was highly predictive of the existence of an EC-ICB (sensitivity, 91.7%; specificity, 89.3%). CONCLUSIONS: An EC-ICB can be effectively detected by intra-atrial sequencing during RPV pacing, and an RPV-high RA time of <89.0 ms was highly predictive.

Uncoupling endocardial bundles coupled by an epicardial bundle in the left atrium and pulmonary veins.

Uncoupling of the endocardial bundles in the left atrium was suggested during modified posterior wall isolation. Although this fact may not be observed because of the possible bridging conduction by epicardial bundles in humans, partially failed transmural ablation in the atrial roof may have iatrogenically unveiled this fact.

Identification of epicardial connections can improve the success rate of first-pass right pulmonary vein isolation.

Background: Epicardial connections between the right pulmonary vein (PV) and the right atrium have been reported. Objective: The purpose of this study was to evaluate the usefulness of our new pulmonary vein isolation (PVI) strategy with identification of these epicardial connections. Methods: Overall, 235 patients with atrial fibrillation were included. High-density mapping of the left atrium was performed to identify the earliest activation sites (EASs) before PVI in all patients. With our new strategy, if EASs around the right PV carina were identified, we ablated these sites and performed usual first-pass circumferential PVI. The patients were divided into 2 groups according to the ablation strategy. One hundred fifteen patients underwent first-pass PVI without information on EASs (nonanalyzed group), and 78 patients underwent ablation at EASs around the right PV carina in addition to PVI (analyzed group). After first-pass ablation around the PV antrum, remapping was performed. Results: High-density mapping before PVI showed that the prevalence of EASs around the right PV carina was 10.9% in all patients (9.6% in the nonanalyzed group, 12.8% in the analyzed group; P = .74. The first-pass right PVI success rate was higher in the analyzed group than in the nonanalyzed group (93.6% vs 82.6%; P = .04). The radiofrequency application time for PVI was significantly shorter in the analyzed group than in the nonanalyzed group (45.6 ± 1.0 minutes vs 51.2 ± 0.9 minutes; P <.05). Conclusion: Identification of epicardial connections before ablation could improve the success rate of first-pass right PVI.

Characteristics of right pulmonary vein with an epicardial connection needing additional carina ablation for isolation.

Background: This study thought to elucidate the anatomical features that can predict an epicardial connection (EC) between the right pulmonary vein (RPV) and right atrium. Methods: We retrospectively analyzed 251 consecutive patients undergoing initial radiofrequency pulmonary vein isolation. We defined EC as present when RPV could not be isolated with circumferential ablation and additional ablation for the conduction gap if needed, and RPV isolation could be achieved by ablation for the earliest activation site >10 mm inside the initial ablation line. Using computed tomography data, we evaluated the RPV bifurcation angle, and the area occupation ratio of the carina region to the RPV antrum (ARC) for predicting EC. In subjects with EC undergoing RPV activation mapping after circumferential ablation, the correlation between conduction delay and bipolar/unipolar potential voltage in the carina region was investigated. Results: There were ECs in 45 out of 251 patients (17.9%). The RPV bifurcation angle (47.7° vs. 38.8°, p < .001) and ARC (37.2% vs. 29.7%, p < .001) were significantly greater in the EC (+) group. Multivariate logistic regression analysis revealed that RPV bifurcation angle (odds ratio [OR]: 1.994, p = .002) and ARC (OR: 3.490, p = .013) were independent predictors of EC. In nine patients with EC undergoing carina region mapping, the unipolar potential voltage was correlated with conduction delay in RPV with EC (R = -0.401, p < .001). Conclusion: Anatomical features suggesting a wider RPV carina region could predict the presence of EC, and potential with high voltage could be helpful for detecting EC connection sites.

Inter-atrial epicardial muscular fibers as a possible source of atrial tachyarrhythmias.

A 22-year-old woman without structural heart disease underwent catheter ablation of frequent premature atrial contractions (PACs). Radiofrequency applications from both the right and left atrium were effective in suppressing or eliminating these PACs. The distance between the right atrial ablation site and the successful ablation site at the right-sided pulmonary venous carina measured 18 mm on the CARTO map, and no cardiac structure, i.e. the inter-atrial septum, was present between those sites. Taken together, the epicardial muscular fibers in the inter-atrial groove were considered to play a role as an arrhythmogenic source of this atrial tachyarrhythmia. Learning objective: Epicardial muscular fibers connecting the right atrium and right-sided pulmonary venous carina are known to preclude isolation of the veins. This epicardial connection in the interatrial groove can be an arrhythmogenic source or part of a reentrant circuit of atrial tachyarrhythmias.

Epicardial connection(s) inside the pulmonary vein antrum isolation lines contribute to subsequent atrial fibrillation: a case report.

Aims: Recent reports have demonstrated that ∼10% of patients with atrial fibrillation (AF) have epicardial connections (ECs) inside the pulmonary vein (PV) antrum isolation (AI) (PVAI) lines, which could be a possible mechanism of failure to achieve a complete PVAI, thus contributing to AF recurrence. Case summary: We present an 80-year-old female case with consistently continuing AF associated with ECs. Epicardial connections involving the PVs were detected in the left and right superior PVs after the completion of the PVAI. The AF steadily terminated after the ablation of those ECs. She has remained well without any AF or symptoms for 2 years post-ablation. Discussion: Those ECs might have played a possible important role in initiating and maintaining the AF. The mechanism(s) of the ECs may be a cornerstone of the failure to achieve a complete PVAI contributing to AF recurrence. Ablation of the EC(s) in addition to the PVAI may be better able to achieve the completion of the PVAI. Thus, physicians should be aware of the possibility of the presence of EC(s) when performing ablation of AF, even though complete PVAI lines have been achieved.

Incidence, distribution, and electrogram characteristics of endocardial-epicardial connections identified by ultra-high-resolution mapping during a left atrial posterior wall isolation of atrial fibrillation.

PURPOSE: The left atrial posterior wall (LAPW) can be a target for atrial fibrillation (AF) catheter ablation but is sometimes difficult to completely isolate due to the presence of endocardial-epicardial connections. We aimed to investigate the incidence and distribution of epicardial residual connections (epi-RCs) and the electrogram characteristics at epi-RC sites during an initial LAPW isolation. METHODS: We retrospectively studied 102 AF patients who underwent LAPW mapping before and after a first-pass linear ablation along the superior and inferior LAPW (pre-ablation and post-ablation maps) using an ultra-high-resolution mapping system (Rhythmia, Boston Scientific). RESULTS: Epi-RCs were observed in 41 patients (40.2%) and were widely distributed in the middle LAPW area and surrounding it. The sites with epi-RCs had a higher bipolar voltage amplitude and greater number of fractionated components than those without (median, 1.09 mV vs. 0.83 mV and 3.9 vs. 3.4 on the pre-ablation map and 0.38 mV vs. 0.27 mV and 8.5 vs. 4.2 on the post-ablation map, respectively; P < 0.001). Receiver operating characteristic analyses demonstrated that the number of fractionated components on the post-ablation map had a larger area under the curve of 0.847 than the others, and the sensitivity and specificity for predicting epi-RCs were 95.4% and 62.1%, respectively, at an optimal cutoff of 5.0. CONCLUSIONS: Among the patients with epi-RCs after a first-pass LAPW linear ablation, areas with a greater number of fractionated components (> 5.0 on the post-ablation LAPW map) may have endocardial-epicardial connections and may be potential targets for touch-up ablation to eliminate the epi-RCs.

Differences in the durability of left atrial posterior wall isolation based on the isolation process.

PURPOSE: The best strategy for durable left atrial posterior wall isolation (PWI) after completion of pulmonary vein isolation (PVI) is not yet determined. This study aimed to examine the differences in the durability of PWI based on the isolation process and the predictors of the reconduction of PWI. METHODS: Among the 221 patients (mean age, 65 ± 11 years) with consecutive non-paroxysmal atrial fibrillation (AF) who completed PVI and PWI, 50 patients undergoing repeat AF ablation were enrolled and divided into the following groups based on how PWI was achieved at the initial procedure: by only the first line on the roof and floor line (group A), by additional gap ablation to the first line or second liner ablation next to the first line (group B), and by adjunct ablation inside the PW revealing the earliest activation (group C). RESULTS: Reconduction of PWI occurred in 24 of the 50 patients (48%). The durability of PWI in groups A, B, and C was 81% (17 of 21 patients), 75% (6 of 8 patients), and 14% (3 of 21 patients), respectively (p < 0.01). In a multivariate analysis, the ablation inside the PW for PWI was the independent predictor of the reconduction of PWI (p < 0.001). CONCLUSION: PWI achieved by the ablation inside the PW resulted in a high rate of reconduction. It may be necessary to aim to achieve the PWI without ablating the inside of the PW to prevent reconduction.

Incidence of epicardial connections between the right pulmonary vein carina and right atrium during catheter ablation of atrial fibrillation: A comparison between the conventional method and unipolar signal modification.

BACKGROUND: When performing an electrical isolation of ipsilateral pulmonary veins (PVs) for atrial fibrillation, physicians often need additional radiofrequency (RF) ablation in the carina region between the superior and inferior PVs to achieve a right PV isolation because of intercaval bundles between the right PVs and right atrium (RA). We compared the efficacy of a high-power and short-duration ablation guided by unipolar signal modification (UM) with the conventional method (CM) for ablating epicardial connections between the right PV carina and RA. METHODS: The study subjects consisted of patients who underwent an initial box isolation of atrial fibrillation from January 2015 to December 2019 at Nara Medical University Hospital. Among these patients, 94 and 65 patients who met the criteria were assigned to the CM and UM groups, respectively. We retrospectively analyzed the anterior ablation line of the right PV using an electroanatomical mapping system. Patients whose initial ablation line included the right PV carina were excluded. RESULTS: Six and seven patients were, respectively, excluded from the CM and UM groups. Among 88 CM group patients, 21 needed additional right PV carina ablation, while among 58 UM group patients, 30 needed additional right PV carina ablation (p = .001). No anatomical factors were associated with the additional right PV carina ablation. CONCLUSIONS: Compared to the CM group, a box isolation was less achievable without RF ablation at the right PV carina in the UM group. We should consider a long-duration ablation for epicardial connections between the right PV carina and RA.

Ethanol Infusion of Vein of Marshall for the Treatment of Persistent Atrial Fibrillation: The Basics and Clinical Practice.

Catheter ablation for persistent atrial fibrillation (PeAF) is particularly challenging, as the clinical outcomes are modest. Pulmonary vein isolation (PVI) plus linear ablation is one of the main strategies for PeAF ablation. Completely durable transmural lesions are difficult to achieve by catheter ablation during mitral isthmus ablation. The ligament of Marshall contains the vein of Marshall (VOM), myocardial tracts and innervation, and serves as arrhythmogenic foci that make it an attractive target in catheter ablation of atrial fibrillation. Additionally, it co-localizes with the mitral isthmus, and may serve as a part of the perimitral isthmus reentrant circuit. Ethanol infusion into the VOM results in rapid ablation of the neighboring myocardium and its innervation. Its incorporation into PVI significantly increases the success rate of mitral isthmus block and the clinical outcome of PeAF ablation.

An Epicardial Connection With a Unidirectional Conduction Property From the Left Atrium to Pulmonary Vein.

The presence of an epicardial connection between the left-sided pulmonary vein and left atrium was suggested during catheter ablation of atrial fibrillation because of sustainable unidirectional entrance conduction after complete endocardial ablation, centrifugal breakout deep inside the pulmonary vein, and immediate elimination of the conduction by point ablation. (Level of Difficulty: Advanced.).