Visualization of Residual Gaps after Linear Ablation using the LUMIPOINT™ Module: A case report.

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.

Combined ethanol and radiofrequency ablation for the elimination of focal atrial tachycardia originating from the Marshall bundle.

Introduction and importance: Atrial tachycardias (AT) originating from the Marshall bundle (MB) are rare and present significant challenges in diagnosis and management. The authors present the case of a 29-year-old male with recurrent AT successfully treated with a combined ethanol and radiofrequency ablation approach. This case highlights the effectiveness of this dual ablation strategy in resolving AT originating from the MB, contributing valuable insights into managing complex AT cases. Case presentation: A 29-year-old male with recurrent, symptomatic palpitations was initially suspected of orthodromic atrioventricular reentrant tachycardia, but an initial electrophysiological study (EPS) failed to induce arrhythmia. Subsequent spontaneous episodes led to a detailed EPS, revealing automatic AT originating presumably from an epicardial focus on the posterior wall of the left atrium (LA). Detailed mapping identified the earliest activation at the vein of Marshall (VoM) ostium within the coronary sinus (CS). Suspecting the involvement of MB structures, VoM ethanol ablation was performed. Complete arrhythmia elimination was achieved with radiofrequency ablation (RFA) at the VoM ostium within the CS, with no recurrence. Discussion: Most cases in the literature are associated with atrial fibrillation (AF) or AT within AF, typically involving re-entry mechanisms. The given case is unique as it presents a highly probable VoM origin of automatic AT with no concomitant AF. The VoM's anatomical and electrophysiological properties make it a potential source of refractory AT. In this case, ethanol ablation supplemented by targeted, limited RFA emerged as an effective strategy, highlighting the importance of comprehensive mapping and tailored ablation approaches in managing complex atrial arrhythmias. Conclusion: The potential implications for clinical practice include recognizing the VoM as a critical target in refractory AT cases and adopting a combined ablation strategy to improve patient outcomes in similarly challenging scenarios.

Interactions of contact force, impedance and power during repeat atrial arrhythmia ablation after previous atrial fibrillation ablation.

BACKGROUND: Acutely effective repeat radiofrequency catheter ablation (RFCA) after previous atrial fibrillation ablation depends on several parameters including local impedance (LI), contact force (CF) and power. OBJECTIVE: To investigate the relationship of LI, CF and power to the LI drop in a repeat atrial RFCA environment. METHODS: Consecutive patients undergoing repeat atrial RFCA were studied. High-quality local electrograms (EGMs) were analyzed regarding morphology changes indicating effective RFCA and associated LI dynamics. The influence of baseline LI, mean CF and power on the LI drop was analyzed. Investigated power levels included ≤25 W, 30 W and ≥40 W. RESULTS: 1390 RFCA points from 48 patients (48 % female, median age 70 years) were analyzed. 40.5% of 309 analyzed EGMs showed effective RFCA morphology changes with a higher median LI drop (effective 19.7 Ω vs partially effective 14.1 Ω, p<0.001). CF showed the highest correlation to the LI drop within high baseline LI and when applying ≥40 W (low baseline LI, R=0.39; intermediate, R=0.66; high, R=0.72). Within low baseline LI regions, CF levels showed a lower correlation to the LI drop (≤25 W, R=0.30; 30 W, R=0.35; ≥40 W, R=0.39). A mean CF ≥10 g resulted in elevated LI drops with higher power compared to lower power within all baseline LI tertiles (p<0.001 each). CONCLUSION: Within rather high baseline LI regions, CF plays a greater role for the maximum LI drop when higher power is chosen. A mean CF ≥10 g ensures increased LI drops with increasing power levels.

Optimizing the Distribution of Ablation Lesions to Prevent Postablation Atrial Tachycardia: A Personalized Digital-Twin Study.

BACKGROUND: Although targeting atrial fibrillation (AF) drivers and substrates has been used as an effective adjunctive ablation strategy for patients with persistent AF (PsAF), it can result in iatrogenic scar-related atrial tachycardia (iAT) requiring additional ablation. Personalized atrial digital twins (DTs) have been used preprocedurally to devise ablation targeting that eliminate the fibrotic substrate arrhythmogenic propensity and could potentially be used to predict and prevent postablation iAT. OBJECTIVES: In this study, the authors sought to explore possible alternative configurations of ablation lesions that could prevent iAT occurrence with the use of biatrial DTs of prospectively enrolled PsAF patients. METHODS: Biatrial DTs were generated from late gadolinium enhancement-magnetic resonance images of 37 consecutive PsAF patients, and the fibrotic substrate locations in the DT capable of sustaining reentries were determined. These locations were ablated in DTs by representing a single compound region of ablation with normal power (SSA), and postablation iAT occurrence was determined. At locations of iAT, ablation at the same DT target was repeated, but applying multiple lesions of reduced-strength (MRA) instead of SSA. RESULTS: Eighty-three locations in the fibrotic substrates of 28 personalized biatrial DTs were capable of sustaining reentries and were thus targeted for SSA ablation. Of these ablations, 45 resulted in iAT. Repeating the ablation at these targets with MRA instead of SSA resulted in the prevention of iAT occurrence at 15 locations (18% reduction in the rate of iAT occurrence). CONCLUSIONS: Personalized atrial DTs enable preprocedure prediction of iAT occurrence after ablation in the fibrotic substrate. It also suggests MRA could be a potential strategy for preventing postablation AT.

SVT quest: The adventure diagnosing narrow QRS tachycardia.

In the field of cardiac electrophysiology, there is a universal desire: the discovery of a flawless diagnostic maneuver for supraventricular tachycardias (SVTs). This is not merely a wish but a shared odyssey. To improve diagnostic accuracy and achieve sufficient sensitivity and specificity, numerous diagnostic maneuvers have been proposed. However, each has its limitations and prompts a search for new diagnostic techniques. This continuous cycle of discovery and refinement, which we titled "SVT Quest" is reviewed in chronological sequence. This adventure in diagnosing narrow QRS tachycardia unfolds in 3 steps: Step 1 involves differentiating atrial tachycardia from other SVTs based on the observations such as V-A-V or V-A-A-V response, ΔAA interval, VA linking, the last entrainment sequence, and response to the atrial extrastimulus. Step 2 focuses on differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia based on the observations such as tachycardia reset upon the premature ventricular contraction during His refractoriness, uncorrected/corrected postpacing interval, differential ventricular entrainment, orthodromic His capture, transition zone analysis, and total pacing prematurity. Step 3 characterizes the concealed nodoventricular/nodofascicular pathway and His-ventricular pathway-related tachycardia based on observations such as V-V-A response, ΔatrioHis interval, and paradoxical reset phenomenon. There is no single diagnostic maneuver that fits all scenarios. Therefore, the ability to apply multiple maneuvers in a case allows the operator to accumulate evidence to make a likely diagnosis. Let's embark on this adventure!

Case Report: Bradycardia in neonatal lupus: differential diagnosis between atrioventricular block and premature atrial contractions with block.

Neonatal lupus may be associated with severe cardiac conduction problems, including high-degree or complete atrioventricular (AV) block, necessitating immediate pacemaker implantation during the neonatal period. However, cardiac manifestations of neonatal lupus may extend beyond AV block. Our case was a full-term female neonate, who presented with fetal arrhythmia and bradycardia with a heart rate of approximately 70-75 beats per minute after birth. Neonatal lupus was diagnosed later due to positive maternal and neonatal anti-SSA/Ro antibody. High-degree AV block was considered initially but bigeminy premature atrial contractions (PACs) with block was confirmed through a detailed evaluation of an electrocardiogram, which demonstrated unfixed PP intervals and fixed RR intervals. Atrial tachycardia (AT) developed when the neonate was 23 days old. The key point that differentiates high-degree AV block from PACs with block is the PP interval. The PP interval is fixed in high-degree AV block and unfixed in PACs with block. Careful differential diagnosis is required in neonates with bradycardia because it may lead to very different management. Our case presents a good illustration of why these arrhythmias need to be differentiated. Furthermore, our case may be the first of neonatal lupus with AT.

Activation patterns and electrophysiologic characteristics of Marshall bundle-related left atrial tachycardias after atrial fibrillation ablation.

BACKGROUND: Epicardial Marshall bundles (MBs) are frequently used in left atrial tachycardias (LATs) after atrial fibrillation (AF) ablation with pulmonary vein isolation and substrate modification. OBJECTIVE: This study sought to classify different activation patterns of MB-mediated LATs and the corresponding electrophysiologic characteristics. METHODS: From 2019 to 2021, 28 cases of atrial tachycardias after AF ablation were diagnosed as MB-mediated LATs by ultrahigh-density mapping and entrainment. Cannulation and mapping in the vein of Marshall (VOM) and epicardial mapping in the MB region were also performed in selected cases to further prove the mechanism. RESULTS: Three activation patterns were identified with a critical isthmus through the MB: perimitral macroreentry (perimitral LAT; n = 20 [71.4%]); left atrial appendage-related reentry (n = 5 [17.9%]); and left pulmonary vein-related reentry (n = 3 [10.7%]). In 18 patients, a characteristic triple potential observed along the previously endocardial left atrial ridge block line was composed of near-field double potentials and far-field MB potential. These findings were further delineated in 24 patients with either cannulation in the VOM (19 patients) or epicardial mapping (5 patients). Ethanol infusion of the VOM resulted in atrial tachycardia termination in 20 of 28 patients. CONCLUSION: Different types of MB-mediated LATs after AF ablation could be identified by ultrahigh-density mapping. Ethanol infusion within the VOM was effective in eliminating these tachycardias.

Electroporation saves the day again: Pulsed-field ablation for phrenic nerve-sparing in right atrial tachycardia.

INTRODUCTION: Pulsed-field ablation (PFA) is a novel nonthermal energy that shows unique features that can be of use beyond pulmonary vein ablation, like tissue selectivity or proximity rather than contact dependency. METHODS AND RESULTS: We report three cases of right focal atrial tachycardias arising from the superior cavoatrial junction and the crista terminalis, in close relationship with the phrenic nerve, effectively ablated using a commercially available PFA catheter designed for pulmonary vein isolation without collateral damage. CONCLUSION: PFA can be useful for treating right atrial tachycardias involving sites near the phrenic nerve, avoiding the need for complex nerve-sparing strategies.

Pulsed-field- vs. cryoballoon-based pulmonary vein isolation: lessons from repeat procedures.

AIMS: Pulsed-field ablation (PFA) is an emerging technology to perform pulmonary vein isolation (PVI). Initial data demonstrated high safety and efficacy. Data on long-term PVI durability and reconduction patterns in comparison to established energy sources for PVI are scarce. We compare findings in repeat ablation procedures after a first PFA to findings in repeat ablation procedures after a first cryoballoon ablation (CBA) based PVI. METHODS AND RESULT: A total of 550 consecutively enrolled patients underwent PFA or CBA index PVI. Repeat ablations in patients with symptomatic atrial arrhythmia recurrences were analysed. A total of 22/191 (12%) patients after index PFA-PVI and 44/359 (12%) after CBA-PVI underwent repeat ablation. Reconduction of any pulmonary vein (PV) was detected by multipolar spiral mapping catheter at each PV with careful evaluation of PV potentials and by 3D-mapping in 16/22 patients (73%) after PFA-PVI and in 33/44 (75%) after CBA-PVI (P = 1.000). Of 82 initially isolated PVs after PFA-PVI, 31 (38%) were reconducting; of 169 isolated PVs after CBA-PVI, 63 (37%) were reconducting (P = 0.936). Clinical atrial tachycardia occurred similarly in patients after PFA (5/22; 23%) and CBA (7/44; 16%; P = 0.515). Roof lines were set more often after PFA- (8/22; 36%) compared with CBA-PVI (5/44; 11%; P = 0.023). Repeat procedure duration [PFA: 87 (76, 123) min; CBA: 93 (75, 128) min; P = 0.446] was similar and fluoroscopy time [PFA: 11 (9, 14) min; CBA: 11 (8, 14) min; P = 0.739] equal between groups at repeat ablation. CONCLUSION: During repeat ablation after previous PFA- or CBA-based PVI, electrical PV-reconduction rates and patterns were similar.

Observational study on the identification of left atrial tachycardia circuits using Local Activation Time Histogram.

BACKGROUND: Mapping of atypical atrial arrythmias arising in the left atrium is often challenging. The Local Activation Time (LAT) Histogram, a new function of the 3D color mapping system CARTO version 7, may help improve identification of atrial tachycardia circuits. We aimed to assess the effectiveness of the LAT Histogram for identification of left atrial tachycardia circuits. METHODS: This retrospective study compared 25 consecutive cases of left atrial tachycardia that were treated before use of LAT Histogram (unused group) and 25 consecutive cases that were treated after introduction of LAT Histogram (used group) at Nagano Chuo Hospital. We evaluated whether we could identify the circuit of left atrial tachycardia from the electrophysiology lab data during ablation and the CARTO system data and whether we could perform effective ablation. RESULTS: Door-to-door time, skin-to-skin time, and fluoroscopy time (p ≤ .011) were all shorter in the LAT Histogram used group versus unused group, while mapping analysis times were longer in the used group (p ≤ .019). A significantly greater number of cases in the LAT Histogram used compared with the unused group had ablation for entrance or exit points (19 vs. 10 cases; p = .001 for first map). Ablation resulted in a return to sinus rhythm and changed cycle length at the first mapping in 20 cases (80%) in the LAT Histogram unused group and in 24 cases (96%) in the used group. CONCLUSIONS: LAT Histogram may provide a simple and effective method to identify entrance and exit locations in left atrial tachycardia.

Benefits from catheter ablation in patients with pulmonary hypertension: Recent advances.

Supraventricular tachycardia (SVT) is a frequent complication of pulmonary hypertension (PH). The most prevalent SVTs are atrial fibrillation (AF) and typical atrial flutter (AFL), followed by focal and macroreentrant atrial tachycardia (AT) and nodal arrhythmia (AV nodal reentry tachycardia or AV reentry tachycardia). SVT is frequently associated with functional deterioration and right ventricular failure in PH patients. According to some data, reestablishing sinus rhythm is associated with clinical improvement. Catheter ablation of typical AFL, nodal tachyarrhythmias, or other less complex focal ATs have been shown to be feasible, acutely effective, and safe in patients with PH. However, the long-term clinical outcome is modified by the recurrence of index arrhythmia and the onset of a new SVT. Due to right atrial dilatation, technical issues can arise when ablation is carried out. The role of catheter ablation in patients with AF or more complex AT is even less effective. The results mirror the success rate in the general AF population with non-paroxysmal AF. However, the data is limited, and electrophysiological procedures are also more often complicated by specific adverse events in a severely frail population. Despite these limitations, catheter ablation is the treatment of choice in less complex SVT, but the indications for AF ablation must be more individualized.

Impact of Ethanol Infusion to the Vein of Marshall in Atrial Fibrillation and Atrial Tachycardia.

The ligament of Marshall is an epicardial structure characterized by its composition of fat, fibrous tissue, blood vessels, muscle bundles, nerve fibers, and ganglia. Its intricate network forms muscular connections with the coronary sinus and left atrium, alongside adjacent autonomic nerves and ganglion cells. This complexity plays a pivotal role in initiating focal electrical activities and sustaining micro- and macro-reentrant circuits, thereby contributing to the onset of atrial fibrillation and atrial tachycardia. However, endocardial ablation in this area may encounter challenges due to anatomical variations and insulation by fibrofatty tissue. Combining ethanol infusion into the vein of Marshall with radiofrequency ablation presents a promising strategy for effectively and safely eliminating this arrhythmogenic structure and terminating associated tachycardias.