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Neither the actual in vivo tissue temperatures reached with 90W/4sec-very high-power short-duration (vHPSD) ablation for atrial fibrillation nor the safety and efficacy profile have been fully elucidated.We conducted a porcine study in which, after right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We compared tissue temperatures close to a QDOT MICRO catheter, between during 90W/4sec-vHPSD ablation during ablation index (AI: target 400)-guided 50W-HPSD ablation, both targeting a contact force of 8-15 g.Maximum tissue temperature reached during 90W/4sec-vHPSD ablation did not differ significantly from that during 50W-HPSD ablation (49.2±8.4ºC versus 50.0±12.1ºC; P=0.69) and correlated inversely with distance between the catheter tip and the thermocouple, regardless of the power settings (r=-0.52 and r=-0.37). Lethal temperature (≥50°C) was best predicted at a catheter tip-to-thermocouple distance cut-point of 3.13 and 4.27 mm, respectively. All lesions produced by 90W/4sec-vHPSD or 50W-HPSD ablation were transmural. Although there was no difference in the esophageal injury rate (50% versus 66%, P=0.80), the thermal lesion was significantly shallower with 90W/4sec-vHPSD ablation than with 50W-HPSD ablation (381.3±127.3 versus 820.0±426.1μm from the esophageal adventitia; P=0.039).Actual tissue temperatures reached with 90W/4sec-vHPSD ablation appear similar to those with AI-guided 50W-HPSD ablation, with the distance between the catheter tip and target tissue being shorter for the former. Although both ablation settings may create transmural lesions in thin atrial tissues, any resulting esophageal thermal lesions appear shallower with 90W/4sec-vHPSD ablation. This article is protected by copyright. All rights reserved.

Neither the actual in vivo tissue temperatures reached with lesion size index (LSI)-guided high-power short-duration (HPSD) ablation for atrial fibrillation nor the safety profile has been elucidated.We conducted a porcine study (n = 7) in which, after right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We compared tissue temperatures reached during 50 W-HPSD ablation with those reached during standard (30 W) ablation, both targeting an LSI of 5.0 (5-15 g contact force).TActual tissue temperatures reached with LSI-guided HPSD ablation appear to be modestly higher, with a shorter distance between the catheter tip and thermocouple achieving lethal temperature, than those reached with standard ablation. HPSD ablation lasting6 s may help minimize lethal thermal injury to the esophagus lying at a close distance.

A new hot balloon system that registers balloon surface temperature (BST) during energy delivery is now available for clinical use in Japan. This study sought to investigate the utility of BST measurement for achievement of pulmonary vein isolation (PVI) by a single-shot energy delivery strategy during hot balloon ablation (HBA).We applied and tested the system in 30 consecutive patients undergoing HBA for paroxysmal or early-persistent atrial fibrillation (AF). We also performed real-time PV potential monitoring using a circular catheter.Acute PVI was achieved with single hot balloon shots in 88% (106/120) of the PVs. Real-time BSTs and PV potentials were recorded in all cases. Mean BST at documentation of PVI was 49.4°C, and acute reconnections were observed in most cases (86%, 12/14) in which the single-shot technique was ineffective. Time-to-isolation (TTI) (23.1 ± 8.7 s vs. 36.3 ± 9.3 s, p .01) and median BST (59.9 ± 2.6°C vs. 55.7 ± 1.9°C, p .01) differed significantly between cases in which PVI was achieved (vs. those in which PVI was not achieved). Multivariable analysis revealed strong association between both TTI and median BST and acute PVI. The best median BST cutoff value for achieving PVI with a single shot was58.7°C (sensitivity 67.0%, specificity 100%).Our data suggest that real-time BST monitoring during energy applications is useful for predicting achievement of acute PVI by a single shot during HBA.

BACKGROUND Although low-voltage zones (LVZs) in the left atrium (LA) are considered arrhythmogenic substrates in some patients with atrial fibrillation (AF), the pathophysiologic factors responsible for LVZ formations remain unclear. OBJECTIVE To elucidate the anatomical relationship between the LA and ascending aorta responsible for anterior LA wall remodeling. METHODS We assessed the relationship between existence of LVZs on the anterior LA wall and the three-dimensional computed tomography image measurements in 102 patients who underwent AF ablation. RESULTS Twenty-nine patients (28%) had LVZs grearer than 1.0 cm2 on the LA wall in the LA-ascending aorta contact area (LVZ group); no LVZs were seen in the other 73 patients (no-LVZ group). The LVZ group (vs. no-LVZ group) had a smaller aorta-LA angle (21.0 ± 7.7° vs. 24.9 ± 7.1°, p = .015), greater aorta-left-ventricle (LV) angle (131.3 ± 8.8° vs. 126.0 ± 7.9°; p = .005), greater diameter of the noncoronary cusp (NCC; 20.4 ± 2.2 vs. 19.3 ± 2.5 mm; p = .036), thinner LA wall-thickness adjacent to the NCC (2.3 ± 0.7 vs. 2.8 ± 0.8 mm; p = .006), and greater cardiothoracic ratio (percentage of the area in the thoracic area, 40.1 ± 7.1% vs. 35.4 ± 5.7%, p

Introduction Preferential pathway conduction is mostly detected as fractionated presystolic-potentials preceding the QRS during premature ventricular contractions (PVCs) and late-potentials during sinus rhythm (SR), but the electrophysiologic mechanisms and significance of these potentials have not been fully clarified. We describe a PVC case series in which the preferential pathway conduction was three-dimensionally visualized. Methods Five PVCs (two from the left coronary cusp, two from the commissure of the left and right coronary cusps, and one from the pulmonary artery) in four patients for which a fractionated presystolic-potential during the PVCs and late-potential during SR were recorded at the successful ablation site were reviewed, and three-dimensional coherent activation maps with the conduction velocity vector during the PVCs and SR were reconstructed. Results At the successful ablation site, an "M"-shaped discrete presystolic-potential and "W"-shaped discrete late-potential were recorded in all patients. The configuration of the inverted electrogram of the presystolic-potential was similar to that of the electrogram exhibiting the late-potential. We created coherent activation maps annotating the onset of the presystolic-potentials during the PVCs and offset of the late-potentials during SR, which suggested bidirectional conduction of the preferential pathway connecting the PVC origin to the myocardium. Conclusion Detailed activation mapping of these PVCs is consistent with the presence of fibers along the aortic or pulmonic valve ring that have preferential directions for conduction. PVCs produce a presystolic-potential. In SR, the fiber is activated late and from the opposite direction, producing an inverted potential inscribed on the end of the QRS.

INTRODUCTION Hot-balloon ablation depends solely on thermal conduction, and myocardial tissue is ablated by only conductive heating from the balloon surface. Despite growing clinical evidence of the efficacy and safety of hot-balloon ablation for atrial fibrillation (AF), the actual tissue temperature and the mechanism of heating during such ablation has not been clarified. To determine, by means of a porcine study, the temperatures of tissues targeted during hot-balloon ablation of AF performed with hot-balloon set temperatures of 73°C or 70°C, in accordance with the temperatures now used clinically. METHODS After a right thoracotomy, thermocouples with markers were implanted epicardially on the superior vena cava (SVC) and pulmonary veins (PVs) in six pigs. The tissue temperatures during hot-balloon ablation (balloon set temperatures of 73°C and 70°C, 180 s/PV) were recorded, and the maximum tissue temperatures and fluoroscopically measured distance from the balloon surface to the target tissues were assessed. RESULTS Sixteen SVC- and 18 PV-targeted energy deliveries were performed. Full-thickness circumferential PV lesions were created with all hot-balloon applications. A significant inverse relation was found between the recorded tissue temperatures and distance (r = -.67; p

Introduction Although electrophysiologic and anatomic factors associated with the need for touch-up radiofrequency (RF) applications after cryoballoon ablation (CBA) for atrial fibrillation (AF) have been well described, those associated with the need for such touch-up after hot balloon ablation (HBA) have not. We aimed to identify factors predictive of the need for touch-up applications following HBA. Methods Anatomic and electrophysiologic factors predictive of the need for touch-up RF ablation were compared between 46 propensity score-matched pairs of patients who underwent HBA or CBA for AF. Results Touch-up RF ablation was more frequently required after HBA than after CBA (57% vs 30%, respectively; P = .01), and mostly at the anterior aspect of the left superior pulmonary vein (LSPV) carina after HBA (35%) but at the inferior aspect of the right inferior PV (RIPV) after CBA (71%). Post HBA touch-up was associated with male gender, a CHA 2 DS 2 -VASc score ≤ 2, PV-left atrial bipolar voltage ≥ 1.35 mV, and PV trunk length ≥ 24.0 mm; post CBA touch-up associated with a history of heart failure. Conclusion Following balloon ablation for AF, there may be a need for touch-up applications, especially at the LSPV ridge after HBA but at the RIPV after CBA. It may behoove operators to expect a need for touch-up following HBA when patients are male, have a CHA2 DS 2 -VASc score ≤ 2 points, when PV-LA bipolar voltage is ≥ 1.35 mV, or when the PV trunk is ≥ 24.0 mm or following CBA when there is a history of heart failure.