BACKGROUND:During catheter ablation of epicardial or intramural outflow tract ventricular arrhythmia (OTVA), the presumed site of origin must often be inferred from coronary venous system (CVS) mapping, which is anatomically constrained. OBJECTIVE:This study sought to evaluate the feasibility and clinical utility of a dual over-the-wire (OTW) microelectrode catheter technique for extensive CVS mapping in OTVAs. METHODS:We prospectively enrolled 30 patients with OTVA exhibiting either a right bundle branch block or a left bundle branch block pattern with V2 or V3 transition. 2 2.7Fr OTW microelectrode catheters were routinely introduced: 1 positioned along the main CVS trunk from the great cardiac vein to the anterior interventricular vein and the other advanced into a peripheral CVS branch. RESULTS:Both catheters were successfully placed in the intended vessels in 28 patients (93%). Among the 26 patients whose earliest activation site was within the CVS, the site with earlier activation within the CVS could be clearly identified in 12 patients (46%) by aligning electrograms from both catheters. Activation timing was equally early between the 2 catheters in 10 patients (39%), requiring pace map findings to delineate the area of interest. In 4 patients (15%), the earliest activation was recorded within the great cardiac vein where both catheters were positioned. The targeted OTVA was eliminated in 27 patients (90%), including 4 patients who underwent successful chemical ablation. CONCLUSION:A dual OTW microelectrode catheter technique was feasible for extensive CVS mapping and was useful in defining the area of interest to perform anatomical approach or chemical ablation.

Ablation using a cryoballoon can minimize the number of sheaths passing through a permanent inferior vena cava filter (pIVCF). Cryoballoon ablation with only a few sheaths can be safely and efficiently performed via the usual femoral vein approach in patients with atrial fibrillation and pIVCF.

An 80-year-old female was referred for catheter ablation of narrow QRS regular tachycardia. During the clinical tachycardia which exhibited long RP' tachycardia, retrograde P wave with short RP interval was repetitively observed (Figure 1). What is the mechanism? At baseline, atrio-His (AH) and His-ventricular (HV) interval was 132 ms and 40 ms, respectively. The earliest atrial activation during ventricular pacing was recorded at the proximal coronary sinus (CS), and the ventriculoatrial (VA) conduction curve revealed decremental property. Para-Hisian pacing showed atrioventricular (AV) nodal pattern with prolongation of VA interval during wide QRS complex compared with during narrow QRS complex without the change of atrial signal sequence. VA conduction was considered to be via retrograde slow pathway. The clinical tachycardia was induced by atrial double extra stimulus pacing without AH jump after administration of isoproterenol. Atrial signal sequence during the tachycardia was identical to that during ventricular pacing. After ventricular overdrive pacing, the tachycardia continued with a V-A-V pattern, and the difference between corrected post pacing interval and tachycardia cycle length was > 110 ms. His-refractory ventricular extra stimulation did not perturb next atrial signal. The clinical tachycardia was diagnosed with fast-slow type atrioventricular nodal reentrant tachycardia (AVNRT). Although the clinical tachycardia basically exhibited long RP' tachycardia, retrograde P wave with short RP interval was repetitively observed as shown in Figure 1, and this phenomenon was reproduced in the electrophysiology lab as well (Figure 2). For the P wave with short RP interval, the earliest atrial activation site was shifted from the proximal CS to the His region (Figure 2). One possible explanation for different timing of the P wave would be premature atrial contraction (PAC) during the tachycardia. However, the P wave with short RP interval was reproducibly identified in the same manner; after two beats of retrograde slow pathway conduction as shown in Figure 2. Another explanation would be retrograde limb of the circuit was converted from slow pathway to fast pathway. Otomo previously reported "fast-fast" type AVNRT which accounted for 0.5% of 950 AVNRT cases [1]. In fast-fast type AVNRT cases with shorter tachycardia cycle length (260 ± 55 ms), AH and HA interval was less than 220 ms and 120 ms, respectively with the earliest atrial activation recorded at His region [1]. In the current case, HA interval with short RP sequence was 132 ms and tachycardia cycle length was 330 ms, both of which were longer than those in previously reported "fast-fast" type AVNRT cases. Interestingly, ventricular extra stimulus pacing with coupling interval less than 500 ms revealed not only retrograde slow pathway conduction but also VA conduction with different atrial signal sequence which was identical to that observed during the tachycardia with short RP interval (Figure 3). This retrograde conduction with the earliest activation site of His region showed decremental property, and one ventricular echo beat was observed during ventricular extra stimulus pacing (Figure 3). Kaneko et al previously reported superior slow pathway which served as a retrograde limb of atypical AVNRT [2]. Among eight patients with fast-slow type AVNRT including a superior slow pathway they reported, double atrial response via retrograde fast pathway and retrograde superior slow pathway was observed during ventricular pacing in three patients. They also reported in another study that the V-A-A-V sequence on ventricular induction and/or on entrainment was frequently (8/9 patients) observed in fast-slow type AVNRT incorporating a superior slow pathway as a retrograde limb, most of which was due to double atrial response [3]. In our case, the retrograde P wave with short RP interval during the clinical long RP' tachycardia was considered to result from retrograde conduction over superior slow pathway from two beats before the immediate previous ventricular activation (double atrial response) (Figure 2) since the atrial signal sequence was identical to that of the second atrial signal during ventricular extra stimulus pacing. As shown in Figure 2, retrograde conduction via superior slow pathway was considered to exhibit Wenckebach block, and short RP interval was observed only when it could conduct to the atrium. For catheter ablation, we applied radiofrequency (RF) energy at the proximal CS targeting the left inferior extension of "typical" slow pathway [4], which terminated the tachycardia 2.6 s after RF application. After RF energy application to the proximal coronary sinus, residual retrograde conduction was confined to the His region and double atrial response was still observed via retrograde fast pathway and retrograde superior slow pathway. Since no tachycardia including AVNRT using superior slow pathway was inducible after elimination of retrograde typical slow pathway, we ended the session and the patient has been free from palpitation since then. The data that support the findings of this study are available from the corresponding author upon reasonable request.

We present case series of coronary vein occlusion by prior radiofrequency (RF) ablation within the coronary venous system (CVS). Case 1 was treated with endocardial RF ablation at the anatomically adjacent site to the earliest activation site identified by mapping of the annular branch which branched off proximally to the occluded site. In Case 2, attempted ethanol infusion to the septal perforator could not be performed due to occlusion of the CVS at the point where RF energy was delivered during the prior procedure. Our case series raise an issue regarding the workflow of ablation therapy for epicardial/intramural ventricular arrhythmias.

BACKGROUND:Cryoballoon pulmonary vein (PV) isolation (PVI) requires PV occlusion, which can be challenging to the large PV. The non-occlusive separate freezing, which involves freezing the superior and inferior portions of the PV ostium without complete occlusion, is often useful in these situations. This study aimed to evaluate the efficacy and long-term results of the non-occlusive separate freezing technique and compare the treatment details of POLARx and Arctic Front Advance Pro (AFA-Pro). METHODS:Patients who underwent cryoballoon PVI using the non-occlusive separate freezing between September 2019 and April 2023 in our institution were analyzed and followed up for 1 year. Success rates of PVI by non-occlusive separate freezing and treatment outcomes were compared between POLARx and AFA-Pro. The 1-year arrhythmia-free survival was also evaluated. RESULTS:Overall, 135 PVs were analyzed (POLARx, n = 63; and AFA-Pro, n = 72). The success rates of PVI for the POLARx and AFA-Pro were 55/63 (87.3%) and 52/72 (72.2%), p = 0.04. The nadir temperatures for the POLARx and AFA-Pro were -52.2 ± 4.7°C and -42.4 ± 7.4°C, p < 0.001. No phrenic nerve injury occurred in either group, but two cases of gastric hypomotility were observed using POLARx. The 1-year arrhythmia-free survival rates for POLARx and AFA-Pro were 86.4% and 81.2%, p = 0.47. CONCLUSIONS:The success rate of PVI using the non-occlusive separate freezing technique was approximately 80% and was significantly higher with POLARx than with AFA-Pro. The 1-year arrhythmia-free survival rate was not significantly different.

BACKGROUND:The novel POLARx cryoballoon ablation (CBA) system offers enhanced cooling properties for the treatment of atrial fibrillation (AF); however, these capabilities may damage adjacent tissues. This study aimed to assess the prevalence and predictors of gastric hypomotility (GH) in patients undergoing pulmonary vein isolation (PVI) and left atrial (LA) roofline ablation using the POLARx. METHODS:Patients who underwent CBA for PVI using the POLARx system were included in this study. Additional LA roofline ablation was performed in patients with non-paroxysmal AF and paroxysmal AF with LA enlargement. GH occurrence was assessed postoperatively by esophagogastroscopy, and the distance between the esophagus and surrounding tissues were measured. RESULTS:Among the 61 patients who underwent PVI, 22 underwent additional LA roofline ablation. GH was confirmed in 12 patients (30.8%) who underwent PVI only and 12 patients (54.5%) who underwent additional LA roofline ablation. Symptomatic GH with acute gastric dilation occurred in three patients, all of whom had undergone roofline ablation. Multivariate analysis, a shorter distance between the esophagus and the midpoint of the vertebral body (odds ratio, 0.74; 95% confidence interval, 0.55-0.98; p = 0.04) was identified as the sole predictor of GH, with a cutoff of 20.0 mm (sensitivity, 80.0%; specificity, 81.8%). CONCLUSION:Adding LA roofline ablation to PVI using the POLARx may increase the risk of GH, particularly when the esophagus is in close proximity to the midpoint of the vertebral body.

Atrial fibrillation (AF) originating from the left atrial posterior wall recurred repeatedly, resulting in immediate recurrence of AF (IRAF). Ethanol infusion into the vein of Marshall (VOM) successfully terminated the AF and simultaneously achieved complete mitral isthmus block. This dual effect underscores the potential utility of VOM ethanol infusion not only for mitral isthmus ablation but also for targeting non-pulmonary vein (non-PV) triggers in complex AF cases.

Introduction:Slow-pathway ablation with cryoablation is a useful tool for treating atrioventricular nodal re-entrant tachycardia (AVNRT). However, reports on the characteristics of atrioventricular block (AVB) during cryoablation are limited. Therefore, we investigated the differences in the appearance of AVB between cryoablation and radiofrequency ablation (RFA). Methods:This dual-center retrospective study included 341 patients who underwent slow-pathway ablation of AVNRT using cryoablation or RFA. Results:A total of 137 patients underwent cryoablation (CRYO group, n = 137), and 204 underwent RFA (RF group, n = 204). Transient AVB during slow-pathway ablation occurred in 33 patients (24.1%) in the CRYO group and 13 patients (6.4%) in the RF group. The time from the beginning of the P-R interval prolongation to the occurrence of second- or third-degree AVB was significantly longer in the CRYO group (6.6 ± 3.7 s) compared to the RF group (1.2 ± 0.3 s, p < 0.01). Three patients in the RF group developed complete AVB requiring pacemaker implantation, whereas none of the patients in the CRYO group developed permanent AVB. After a median follow-up of 221 ± 186 days, AVNRT recurred in 13 patients (9.5%) in the CRYO group and in 7 patients (3.4%) in the RF group (p < 0.01). Conclusion:Cryoablation gradually induces atrioventricular conduction disturbances when AVB occurs inadvertently, taking longer than RFA. Compared to RFA, cryoablation has a relatively high incidence of transient AVB during slow-pathway ablation but does not result in permanent AVB.

BACKGROUND The anatomical approach for the management of para-Hisian ventricular arrhythmias (VAs) with QRS morphological changes after catheter ablation (CA) has not been well investigated. OBJECTIVE We aimed to evaluate the electrocardiographic and electrophysiological findings and ablation outcomes of paraHisian VAs with QRS morphological changes after CA. METHODS Of the 30 patients who underwent CA for para-Hisian VAs at 4 institutions, 10 (33%) had QRS morphological changes after ablation. All 10 patients underwent an anatomical approach, targeting the site anatomically opposite to the site where the QRS morphology had been changed by ablation. We investigated the safety and efficacy of the anatomical approach. RESULTS Of the 10 patients evaluated, the approach was switched from the right ventricular septum to the left ventricular septum/aortic root in 7 (70%) (RL group) whereas 3 (30%) underwent left-to-right switches (LR group). After CA, the precordial transition zone tended to be earlier in the RL group and later in the LR group. In the RL group, successful VA suppression was achieved, despite suboptimal pace map concordance from the left side or a relatively delayed earliest activation time. Of the 10 patients who underwent an anatomical approach, 8 (80%) had procedural success, and ablation was discontinued in 1 (10%) because of the risk of atrioventricular block. CONCLUSION The anatomical approach showed promising results regarding safety and efficacy. Therefore, it should be considered when QRS morphological changes are observed during or after CA of para-Hisian VAs.

Background: Ethanol infusion into the vein of Marshall (EIVOM) has been performed as an adjunctive atrial fibrillation therapy. However, the time course change, quantitative lesion investigation, and effects on epicardial fat pads and fractionated atrial electrograms created by EIVOM have never been investigated. Objective: This study aimed to perform a quantitative analysis of lesions created by EIVOM. Methods: We created voltage maps using a 3-dimensional mapping system immediately before and 30 minutes and 60 minutes after performing EIVOM to study the time course change in the lesions. We compared differences in the average contact force value required for successful conduction block in the Marshall vein area of patients with and without EIVOM. We also investigated effects of EIVOM on the area of complex fractionated atrial electrograms before and after EIVOM. We measured the total epicardial fat pad volume before and after EIVOM by computed tomography. Results: Voltage was significantly reduced after EIVOM, and there were significant differences in voltage reduction between the control status and 30 minutes and 60 minutes after EIVOM (P < .05). The average contact force value was significantly lower with vs without EIVOM (P < .05). The total epicardial fat volume and complex fractionated atrial electrogram area also significantly decreased after EIVOM (P < .05). Conclusion: EIVOM provided significant therapeutic effects on the left atrial tissue perpetuating atrial fibrillation, which was demonstrated by a quantitative analysis.

Background: Slow pathway elimination of the atrioventricular node (AVN) is essential to treat AVN reentrant tachycardia (AVNRT). However, injury to the AVN conduction (IAVN) is one of the serious complications. Cryofreezing energy is expected to reduce the incidence of IAVN. This study aimed to investigate the usefulness of a novel method to avoid IAVN during cryoablation of AVNRT. Methods: A total of 157 patients (average age, 65.8 years; male, 71) suffering from AVNRT were included. Once the AVNRT terminated during cryo-ablation, then rapid atrial constant pacing (RACP) was performed during freezing at a rate lower 10 bpm than that inducing Wenchebach AV block in 74 (47.1 %) patients (Group A). The RACP rate was decreasingly reduced by 10 bpm in case of the occurrence of IAVN. When the RACP reached 100 bpm, the cryoablation was prematurely terminated. Group B patients (83 = 52.9 %) underwent cryoablation during sinus rhythm. All patients were allocated in a randomized fashion. We compared the severity of the IAVN between Groups A and B. Results: There were no significant differences at 12 months regarding the freedom from the AVNRT between Groups A and B. However, the duration of the IAVN was significantly longer in Group B than A (p = 0.02). There were no significant differences regarding the distance between the His recording sites and successful ablation sites between Groups A and B. No permanent IAVN requiring pacemaker implantation was provoked in either group. Conclusion: RACP was useful to avoid sustained and serious IAVN during cryoablation of AVNRT. (c) 2023 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Introduction: Gastric hypomotility (GH) is a major complication of atrial fibrillation (AF) ablation. We aimed to clarify whether additional cryoballoon ablation (CBA) of the left atrial (LA) roof is associated with GH. Methods and Results: This study included 54 patients with non-paroxysmal AF who underwent CBA for pulmonary vein isolation and of the LA roof line. GH was defined according to the results of esophagogastroscopy performed 2 days after ablation. GH was observed in 10 patients. There were significant differences in LA diameter (LAD), right inferior pulmonary vein (RIPV) diameter, and the height of the LA roof from the point where the LA posterior wall and esophagus make contact between patients with (GH+) and without GH (GH–) (LAD: 41.0 [36.3–41.8] mm vs. 46.5 [42.8–50.0] mm, p<0.01; RIPV diameter: 19.7 [19.0–20.5] mm vs. 23.2 [21.2–24.9] mm, p<0.01; height of LA roof: 5.7 [5.1–6.1] mm vs. 8.8 [7.1–11.2] mm for, p<0.01, respectively). Multivariate analysis revealed that LA roof height was a predictor of GH. Moreover, Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM) scores increased significantly 1 week after ablation (from 1.0 [0.0–2.8] to 5.0 [3.0–11.0], p=0.03) in patients with GH. Conclusion: The height of the LA roof may be a predictor of GH after CBA of the LA roof line. Additionally, GH-related symptoms may still appear 1 week after ablation.

BACKGROUND:The effectiveness of cryoballoon ablation (CBA) of the left atrial (LA) roof in addition to pulmonary vein isolation (PVI) using a novel cryoballoon catheter, POLARx, remains unclear. METHODS:This study compared the efficacy of LA roof line ablation and PVI using POLARx (Boston Scientific) or AFA-Pro (Medtronic) in 100 patients with persistent atrial fibrillation. The right superior pulmonary vein (PV) anchoring and raise-up techniques were consistently used for LA roof line ablation, and rapid right ventricular pacing was applied if the cryoballoon temperature did not reach -40°C. RESULTS:Complete conduction block at the LA roof could be obtained in all patients with POLARx and in 98.0% of patients with AFA-Pro. Rapid right ventricular pacing was needed in 64.0% of patients with AFA-Pro and in no patients with POLARx. During LA roof line ablation, the nadir cryoballoon temperature was significantly lower with POLARx than with AFA-Pro (right: -54.2°C ± 4.4°C vs. -46.0°C ± 5.4°C; central: -56.8°C ± 4.4°C vs. -45.7°C ± 4.8°C; left: -56.1°C ± 4.3°C vs. -46.1°C ± 5.7°C), and the cryoballoon temperature reached -40°C earlier with POLARx than with AFA-Pro (right: 30.8 ± 7.4 s vs. 74.1 ± 37.7 s; central: 28.2 ± 5.2 s vs. 62.9 ± 30.9 s; left: 29.8 ± 5.8 s vs. 69.6 ± 40.7 s). CONCLUSION:The nadir cryoballoon temperature with POLARx was approximately 10°C lower than with AFA-Pro, consistently dropping below -40°C during LA roof line CBA. Thus, a complete conduction block of the LA roof line can be easily accomplished using right superior PV anchoring and the raise-up techniques without the need for rapid right ventricular pacing with POLARx.