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Background: Macroreentrant atrial tachycardia (ATs) through epicardial conduction is depicted as a focal AT on 3-D mapping, i.e., pseudo-focal AT. A new feature of the Rhythmia mapping system (Boston Scientific), the ''LUMIPOINT module'', can highlight all electrocardiograms (EGMs) above a threshold determined by an adjustable confidence slider (CS). Lowering the CS (L-CS) may highlight undetected electrograms (EGMs) at the nominal CS setting, potentially enabling visualization of the critical isthmus of pseudo-focal ATs. Methods and results: This study included 3 ATs after linear ablation of two left atrial roof-dependent ATs (cases 1 and 2) and one peri-mitral flutter (case 3). All ATs were diagnosed as pseudo-focal AT according to an electrophysiological study and the Rhythmia mapping system with the LUMIPOINT module. The L-CS method consisted of the following steps: 1. Set the LUMIPOINT activation window to the time difference before and after the linear ablation line. 2. Highlight the two regions before and after the linear ablation line. 3. Gradually lower the CS value from the nominal setting of 85 % by 5–10 %. By the L-CS method in cases 1–3, the 2-sided highlighted areas before and after the prior linear ablation lesion gradually expanded and eventually fused. EGMs at the fusion sites of the highlighted areas exhibited fragmented EGMs with a low voltage, where a single-shot ablation terminated the targeted ATs. Conclusion: The L-CS method was useful for the visualization of residual gaps and identification of targeted ablation sites in cases of pseudo-focal AT after linear ablation of macroreentrant ATs.

This paper presents a novel approach to gap mapping in pulmonary vein isolation (PVI) for atrial fibrillation (AF) treatment, utilizing the real-time Ripple (RR) technique. Radiofrequency (RF) catheter ablation, particularly encircling PVI, is a common intervention for AF. Identifying left atrium–pulmonary vein conduction gaps is crucial for achieving PVI with minimal additional ablation if first-pass PVI is unsuccessful. However, identifying conduction gaps can be relatively challenging, often necessitating manual electrocardiogram reannotation due to the limitations of local activation time (LAT) maps. In the case of a 63-year-old patient with drug-resistant symptomatic persistent AF, the RR technique was utilized to identify conduction gaps during RF ablation. The technique involved pausing fast anatomical mapping (FAM), activating Ripple map (RM) feature on the CARTO 3 system and acquiring points with an ultrahigh-resolution mapping catheter. This approach revealed that the actual site of earliest activation differs from the LAT map indication, enabling successful PVI.The RM feature's capability to reflect actual excitation propagation without reliance on map annotations was crucial for precise conduction gap identification, overcoming inter-operator variability and inaccuracies of conventional methods. The RR technique not only facilitated real-time analysis during gap mapping but also significantly reduced the procedure time, minimizing potential complications.This case report highlights the efficacy of the RR technique in real-time gap mapping, demonstrating its value in cases where first-pass PVI is unsuccessful. The integration of this technique into PVI procedures can enhance both the accuracy and efficiency of catheter ablation for AF.

Introduction: Acute pulmonary vein reconnection (PVR) via epicardial fibers can be found during observation period after PV isolation, the characteristics and related factors have not been fully studied. We aimed to investigate the prevalence, locations, electrogram characteristics, and ablation parameters related to acute epicardial pulmonary vein reconnection (AEPVR). Methods: Acute PVR was monitored during observation period after PV isolation. AEPVRs were mapped and distinguished from endocardial conduction gaps. The clinical, electrophysiological characteristics and lesion set parameters were compared between patients with and without PVR. They were also compared among AEPVR, gap‐related reconnection, and epicardial PVR in repeat procedures. Results: A total of 56.1% acute PVR were AEPVR, which required a longer waiting period (p <.001) than endocardial gap. The majority of AEPVR were connections from the posterior PV carina to the left atrial posterior wall, followed by late manifestation of intercaval bundle conduction from the right anterior carina to right atrium. AEPVR was similar to epicardial PVR in redo procedures in distribution and electrogram characteristics. Smaller atrium (p <.001), lower impedance drop (p =.039), and ablation index (p =.028) on the posterior wall were independently associated with presence of AEPVR, while lower interlesion distance (p =.043) was the only predictor for AEPVR in acute PVR. An integrated model containing multiple lesion set parameters had the highest predictive ability for AEPVR in receiver operating characteristics analysis. Conclusions: Epicardial reconduction accounted for the majority of acute PVR. AEPVR was associated with anatomic characteristics and multiple ablation‐related parameters, which could be explained by nondurable transmural lesion or late manifestation of conduction through intercaval bundle. [ABSTRACT FROM AUTHOR]

Aims Linear lesions are routinely created by radiofrequency catheter ablation. Unwanted electrical conduction gaps can be produced and are often difficult to ablate. This study aimed to clarify the characteristics of conduction gaps during atrial fibrillation ablation by analysing bidirectional activation maps using a high-density mapping system (RHYTHMIA). Methods and results This retrospective study included 31 patients who had conduction gaps along pulmonary vein (PV) isolation or box ablation lesions. Activation maps were sequentially created during pacing from the coronary sinus and PV to reveal the earliest activation site, defined by the entrance and exit. The locations, length between the entrance and exit (gap length), and direction were analysed. Thirty-four bidirectional activation maps were drawn: 21 were box isolation lesions (box group), and 13 were PV isolation lesions (PVI group). Among the box group, nine conduction gaps were present in the roof region and 12 in the bottom region, while nine in right PV and four in left PV among the PVI group. Gap lengths in the roof region were longer than those in the bottom region (26.8 ± 11.8 vs. 14.5 ± 9.8 mm; P = 0.022), while those in right PV tended to longer than those in left PV (28.0 ± 15.3 vs. 16.8 ± 8.0 mm, P = 0.201). Conclusion The entrances and exits of electrical conduction gaps were separated, especially in the roof region, indicating that epicardial conduction might contribute to gap formation. Identifying the bidirectional conduction gap might indicate the location and direction of epicardial conduction. [ABSTRACT FROM AUTHOR]

Beyond pulmonary vein (PV) isolation, anatomic isthmus transection is an adjunctive strategy for persistent atrial fibrillation. Data on the durability of multiple lines of block remain scarce. The purpose of this study was to evaluate the impact of gaps within such a lesion set. We followed 291 consecutive patients who underwent (1) vein of Marshall ethanol infusion, (2) PV isolation, and (3) mitral, cavotricuspid, and dome isthmus transection. Dome transection relied on 2 distinct strategies over time: a single roof line with touch-ups applied in case of gap demonstrated by conventional maneuvers (first leg), and an alternative floor line if the roof line exhibited a gap during high-density mapping with careful electrogram reannotation (second leg). Twelve-month sinus rhythm maintenance was 70% after 1 procedure and 94% after 1 or 2 procedures. Event-free survival after the first procedure was lower in case of residual gaps within the lesion set (log-rank, P =.004). Delayed gaps were found in 94% of a second procedure performed in the 69 patients relapsing despite a complete lesion set with PV gaps increasing the risk of recurrence of atrial fibrillation (67% vs 34%; P =.02) and anatomic isthmus gaps supporting a majority of atrial tachycardias (60%). Between the first leg and the second leg , a significant decrease was found in roof lines considered blocked during the first procedure (99% vs 78%; P <.001) and in delayed dome gaps observed during a second procedure (68% vs 43%; P =.05). Gaps are arrhythmogenic and can be reduced by optimized ablation and assessment of lines of block. Closing these gaps improves sinus rhythm maintenance. [ABSTRACT FROM AUTHOR]

Background: Mitral isthmus gaps have been ascribed to an epicardial musculature anatomically related to the great cardiac vein (GCV) and the vein of Marshall (VOM). Their lumen offers an access for radiofrequency application or ethanol infusion, respectively.Objective: The purpose of this study was to evaluate the frequency of mitral isthmus gaps accessible via the GCV lumen, to assess their location around the GCV circumference, and to propose an efficient ablation strategy when present.Methods: One hundred consecutive patients underwent VOM ethanol infusion (step 1) and endocardial linear ablation from the mitral annulus to the left inferior pulmonary vein (step 2). In cases of mitral isthmus gap, endovascular ablation of the GCV anchored wall facing the left atrium was systematically performed (step 3), while the opposite GCV free wall was targeted in case of block failure only (step 4).Results: After VOM ethanol infusion and endocardial ablation, mitral isthmus block occurred in 51 patients (51%). Pacing maneuvers and activation sequences demonstrated an epicardial gap via the VOM in 2 patients (2%) and via the GCV in 47 patients (47%). In the latter case, block was achieved at the GCV anchored wall in 42 patients (89%) and the GCV free wall in 5 patients (11%). Global success rate of mitral isthmus block was 98%. No tamponade occurred.Conclusion: With the advent of VOM ethanol infusion, residual mitral isthmus gaps are mostly eliminated within the first centimeter of the GCV. Thorough mapping of the entire circumference of the GCV wall can help identify these epicardial gaps. [ABSTRACT FROM AUTHOR]

Background: Several methods have been reported for locating the conduction gap (CG) in the pulmonary vein isolation (PVI) ablation line. However, the value of the interval between far-field atrial potential (FFP) and pulmonary vein potential (PVP) remains unknown.Methods: Consecutive patients with a CG during observation on the table after PVI were included. The PVP, FFP, and the CG location were evaluated to develop a novel algorithm to identify the CG location in the left superior pulmonary vein. The performance of this novel algorithm was prospectively tested in a validation cohort of consecutive patients undergoing repeat PVI ablation.Results: A total of 116 patients with atrial fibrillation (AF) were recruited, 56 of whom formed the validation cohort. The interval between FFP and PVP of the left superior pulmonary vein was associated with the CG location, and an interval

Electrophysiological studies have rarely evaluated the sites prone to pulmonary vein (PV) conduction gap during cryoballoon ablation (CBA) for atrial fibrillation (AF). In addition, no studies have analyzed the sequence of PV potentials just before PV isolation during CBA for AF. Of the 238 patients who underwent first-time CBA for paroxysmal AF, 115 PVs of 29 patients who underwent repeat session due to recurrence after the procedure were retrospectively evaluated in the study. We evaluated the disappearance pattern of PV potential and PV reconnection on intracardiac electrograms and investigated whether the conduction gap site of the PV was related to the last remaining earliest PV potential (EP) and sequence pattern during the first-time CBA. Time to isolation was observed in 81 PVs during the first-time CBA. At the repeat session, PV reconnection was only observed in 22 of 81 PVs. PV potentials disappeared with sequence changes in 36 PVs and without sequence changes in 38 PVs. Multivariate analysis demonstrated that disappearance of PV potentials without change in the EP site but with delay or disappearance of other PV potentials was independently associated with PV reconnection (12/22 PVs [55%] vs. 4/59 PVs [6.8%]; odds ratio 14.4; 95% confidence interval 3.75–55.5; p < 0.001). In 19 of 22 (86%) reconnected PVs, PV conduction gap sites at repeat ablation corresponded with the last remaining EP sites during first-time CBA. In conclusion, disappearance pattern of the PV potential and the last remaining EP during the CBA can predict PV reconnection and gap site. [ABSTRACT FROM AUTHOR]

Introduction: Local impedance (LI) drops during radiofrequency ablation can predict lesion formation. Some conduction gaps during pulmonary vein isolation (PVI) can be associated with nonendocardial connections. This study aimed to investigate the incidence, characteristics, and predictors of endocardial and nonendocardial conduction gaps during an LI‐guided PVI. Methods and Results: We prospectively enrolled 157 consecutive patients undergoing an initial LI‐guided extensive PVI of atrial fibrillation (AF). After the first‐pass encirclement, the residual conduction gaps and reconnected gaps were mapped using Rhythmia (Boston Scientific) and a mini‐basket catheter. Right and left PV (RPV/LPV) gaps were observed in 22.3% and 18.5% of the patients, respectively: 27 endocardial and 49 nonendocardial gaps. The carina regions were common sites for the gaps (51 carina‐related vs. 25 noncarina‐related). The carina‐related gaps consisted of more nonendocardial gaps than endocardial gaps (RPVs: 90.0% vs. 10.0%, p =.001; LPVs: 76.2% vs. 23.8%, p <.001). A univariate analysis revealed that paroxysmal AF and the left atrial (LA) volume index for RPV endocardial gaps (odds ratio [OR]: 8.640 and 0.946; p =.043 and 0.009), minor right inferior PV diameter for RPV nonendocardial gaps (OR: 1.165; p =.028), and major left inferior PV diameter for LPV endocardial gaps (OR: 1.233; p =.028) were significant predictors. Conclusions: During the LI‐guided PVI, approximately two‐thirds of the conduction gaps were nonendocardial. The carina regions had more conduction gaps than noncarina regions, which was due to the presence of nonendocardial connections. Paroxysmal AF, a lower LA volume index, and larger inferior PV diameters may increase the risk of conduction gaps. [ABSTRACT FROM AUTHOR]

We report a case of atrial trigeminy induced only at a specific pacing cycle length in a patient with residual pulmonary vein conduction gap. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflict of interest: The present work was supported by Abbott, Advanced applications department.

Introduction: When performing linear ablation, creating contiguous and transmural lesions are technically challenging due to the difficulty in finding electrical conduction gaps. We hypothesized that high‐density mapping could identify the gaps. Methods and Results: This study included consecutive patients who underwent conduction gap mapping of de novo lesions (41 patients, 55 lines) and previous lesions (25 patients, 34 lines). We analyzed the utility of bipolar and unipolar conduction gap mapping and retrospectively assessed the voltage and morphology of the bipolar electrograms at the gap sites. Bipolar and unipolar propagation maps were classified into three types: the propagation wavefront traveled through the linear ablation lesions (direct leak), the wavefront jumped to an opposite site across the line and returned to the line (jump and return leak), and others (indefinite leak). In the jump and return leak maps, the site where it returned suggested a conduction gap site. Bipolar propagation maps identified 30 (54.5%) conduction gaps and unipolar maps identified 40 (72.7%) gaps at de novo linear ablation lesions (P =.01), and 32 (94.1%) gaps and 33 (97.1%) gaps, respectively, at previous lesions (P =.56). Bipolar voltage mapping did not add any further efficacy in detecting conduction gaps, and the morphology of the electrograms recorded at the gap sites was not related to the types of propagation maps. Conclusion: Conduction gaps of linear ablation lesions can be visualized by high‐density mapping with a high probability. Unipolar propagation, when used with bipolar mapping, may help detect conduction gap sites. [ABSTRACT FROM AUTHOR]

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Background: The reconnection of left atrial-pulmonary vein (LA-PV) conduction after the initial procedure of pulmonary vein (PV) isolation is not rare, and is one of the main cause of atrial fibrillation (AF) recurrence after PV isolation.Objective: We investigated feasibility of a new ultrahigh-resolution mapping system using a 64-pole small basket catheter for the identification of LA-PV conduction gaps.Methods: This prospective study included 31 consecutive patients (20 with persistent AF) undergoing a second ablation after a PV isolation procedure with LA-PV reconnected conduction at any of the 4 PVs. An LA-PV map was created using the mapping system, and ablation was performed at the estimated gap location.Results: The propagation map identified 54 gaps from 39 ipsilateral PV pairs, requiring manual electrogram reannotation for 23 gaps (43%). Gaps at the anterior and carinal regions of left and right ipsilateral PVs required manual electrogram reannotation more frequently than the other regions. The voltage map could identify the gap only in 19 instances (35%). Electrophysiological properties of the gaps (multiple gaps in the same ipsilateral PVs, conduction time, velocity, width, and length) did not differ between those needing and not needing manual electrogram reannotation. During the gap ablation, either the activation sequence alteration or elimination of PV potentials was observed using a circular catheter placed in the PV, suggesting that all the identified gaps were correct.Conclusion: This new electroanatomic mapping system visualized all the LA-PV gaps in patients undergoing a second AF ablation. [ABSTRACT FROM AUTHOR]

Aims: Linear lesions are routinely created by radiofrequency catheter ablation. Unwanted electrical conduction gaps can be produced and are often difficult to ablate. This study aimed to clarify the characteristics of conduction gaps during atrial fibrillation ablation by analysing bidirectional activation maps using a high-density mapping system (RHYTHMIA)., Methods and Results: This retrospective study included 31 patients who had conduction gaps along pulmonary vein (PV) isolation or box ablation lesions. Activation maps were sequentially created during pacing from the coronary sinus and PV to reveal the earliest activation site, defined by the entrance and exit. The locations, length between the entrance and exit (gap length), and direction were analysed. Thirty-four bidirectional activation maps were drawn: 21 were box isolation lesions (box group), and 13 were PV isolation lesions (PVI group). Among the box group, nine conduction gaps were present in the roof region and 12 in the bottom region, while nine in right PV and four in left PV among the PVI group. Gap lengths in the roof region were longer than those in the bottom region (26.8 ± 11.8 vs. 14.5 ± 9.8 mm; P = 0.022), while those in right PV tended to longer than those in left PV (28.0 ± 15.3 vs. 16.8 ± 8.0 mm, P = 0.201)., Conclusion: The entrances and exits of electrical conduction gaps were separated, especially in the roof region, indicating that epicardial conduction might contribute to gap formation. Identifying the bidirectional conduction gap might indicate the location and direction of epicardial conduction., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Although both high-power (HP) ablation and lesion size index (LSI) are novel approaches to make effective lesions during pulmonary vein isolation (PVI) for atrial fibrillation (AF), the optimal LSI in HP ablation for PVI is still unclear. Our study sought to explore the association between LSI and acute conduction gap formation and investigate the optimal LSI in HP ablation for PVI., Methods: A total of 105 consecutive patients with AF who underwent HP ablation guided by LSI (LSI-guided HP) for PVI in our institute between June 2019 and July 2020 were retrospectively enrolled. Each ipsilateral PV circle was subdivided into four segments, and ablation power was set to 50 W with target LSI values at 5.0 and 4.0 for anterior and posterior walls, respectively. We compared the LSI values with and without acute conduction gaps after the initial first-pass PVI., Results: PVI was achieved in all patients, and the incidence of first-pass PVI was 78.1% (82/105). A total of 6,842 lesion sites were analyzed, and the acute conduction gaps were observed in 23 patients (21.9%) with 45 (0.7%) lesion points. The gap formation was significantly associated with lower LSI (3.9 ± 0.4 vs. 4.6 ± 0.4, p < 0.001), lower force-time integral (82.6 ± 24.6 vs. 120.9 ± 40.4 gs, p < 0.001), lower mean contact force (5.7 ± 2.4 vs. 8.5 ± 2.8 g, p < 0.001), shorter ablation duration (10.5 ± 3.6 vs. 15.4 ± 6.4 s, p < 0.001), lower mean temperature (34.4 ± 1.4 vs. 35.6 ± 2.6°C, p < 0.001), and longer interlesion distance (4.4 ± 0.3 vs. 4.3 ± 0.4 mm, p = 0.031). As per the receiver operating characteristic analysis, the LSI had the highest predictive value for gap formation in all PVs segments, with a cutoff of 4.35 for effective ablation (sensitivity 80.0%; specificity 75.4%, areas under the curve: 0.87). The LSI of 4.55 and 3.95 had the highest predictive value for gap formation for the anterior and posterior segments of PVs, respectively., Conclusion: Using LSI-guided HP ablation for PVI, more than 4.35 of LSI for all PVs segments showed the best predictive value to avoid gap formation for achieving effective first-pass PVI. The LSI of 4.55 for the anterior wall and 3.95 for the posterior wall were the best cutoff values for predicting gap formation, respectively., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Cai, Wang, Niu, Chu, Hua, Zhang and Yao.)

Recently, a novel linear multielectrode mapping/ablation catheter was developed. We present a case in which mitral isthmus line ablation was undertaken with this catheter and showed repeated conduction recovery at the same site on the line. Mapping with this multielectrode catheter along the whole lesion allowed recording of abrupt conduction resumption. [ABSTRACT FROM PUBLISHER]

We herein report a 79-year-old man with recurrent atrial flutter (AFL) following catheter ablation for pulmonary vein (PV) isolation and block line of the cavotricuspid isthmus. An electrophysiological study and three-dimensional mapping results revealed left atrium (LA)-PV macroreentrant flutter caused by a conduction gap, possibly correlated to prior application, which mimicked cavotricuspid isthmus-dependent AFL. This LA-PV flutter was terminated after applying radiofrequency to the gap at the antrum near the bottom left inferior PV in the posterior LA wall. During follow-up, the patient did not present with atrial tachyarrhythmias; antiarrhythmic drugs were therefore not administered.

High-resolution mapping is useful to identify reconnection gaps in the pulmonary vein after pulmonary vein isolation for atrial fibrillation. However, it is sometimes difficult to differentiate pulmonary vein potentials from far-field potentials because of very low amplitudes. Our purpose was to evaluate the usefulness of a novel differential atrial pacing method to differentiate reconnected pulmonary vein potentials from isolated pulmonary vein potentials. This retrospective observational study included 34 patients with atrial fibrillation (22 men; mean age, 64 ± 14 years; 28 with paroxysmal atrial fibrillation) who underwent radiofrequency or cryoballoon ablation. Following pulmonary vein isolation, we created a high-resolution activation map during pacing from both the coronary sinus and left atrial appendage. We compared the characteristics of the pulmonary vein potentials and the pattern of activation between the reconnected and isolated pulmonary veins. We analyzed 131 pulmonary veins and found reconnections in 41 pulmonary veins (R group); 90 pulmonary veins had no reconnection (NR group). The R group had a significantly shorter distance between the earliest pulmonary vein activation sites in both activation maps, compared with the NR group (5.22 ± 0.53 mm versus 17.08 ± 0.36 mm, respectively; P < 0.0001). The amplitude of the pulmonary vein potentials was higher in the R group versus the NR group (0.61 ± 0.05 mV versus 0.04 ± 0.03 mV, respectively; P < 0.0001). Six gaps (14%) in the R group that were unrecognized using a conventional method were identified using our novel method. In conclusion, differential atrial pacing was useful to identify pulmonary vein reconnection gaps during ablation using a novel high-resolution mapping system.

Background: The electrophysiological characteristics of residual conduction gaps between the left atrium (LA) and pulmonary veins (PVs) after HotBalloon-based wide antral ablation (HBWA) of atrial fibrillation (AF) remain incompletely understood. This study aimed to characterize the residual gaps by means of ultra-high-resolution mapping., Methods and results: A total of 55 AF patients underwent HBWA by a predetermined protocol (6-shot total-based antral approach). LA-PV maps were created using 64-electrode minibasket catheters. In total, 55 residual gaps were identified among 26 (47%) patients. Residual gaps included 33 left superior (LS: 60%), 10 left inferior (18%), 6 right superior (11%), and 6 right inferior (11%) PVs. Those gaps demonstrated both extremely lower bipolar amplitudes (0.11 [interquartile range: 0.06-0.27] mV) and conduction velocities (0.75±0.27 m/s); however, the length was confined (10.3±4.1 mm) except for the LSPV anterior carina (12.2±2.4 mm) region. Among the carina regions, all gaps had far-field potentials consistently added to the PV potentials. Left atrial appendage pacing to split the far-field activity identified confined gap regions (6.7±1.9 mm). Touch-up ablation eliminated the residual PV potentials in all cases., Conclusions: HBWA resulted in a certain degree of residual gap conduction in particular antral regions. These gaps exhibited narrow lengths with lower amplitudes, and often had far-field recordings from the left atrial appendage. Combined with pacing maneuvers, ultra-high-resolution activation maps could both visualize all confined gaps and ensure a bare minimum of touch-up ablations in all patients with gap conduction.