Background - The mechanism of esophageal thermal injury (ETI; esophageal mucosal injury and periesophageal nerve injury leading to gastric hypomotility) remains unknown when using a high-power short-duration (HP-SD) setting. This study sought to evaluate the characteristics of esophageal injuries in atrial fibrillation (AF) ablation using a high-power short-duration (HP-SD) setting. Methods - After exclusion of 5 patients with their esophagus at the right portion of left atrium (LA) and 21 patients with additional ablations such as box isolation and/or low voltage ablation in LA posterior wall, 271 consecutive patients (62 ± 10 years, 56 women) who underwent pulmonary vein isolation (PVI) by radiofrequency catheter ablation were analyzed. In the 101 patients, a HP-SD setting at 45-50 W with an Ablation Index module® was used (HP-SD group). In the remaining 170 patients before introduction of the HP-SD setting, a conventional power setting of 20-30 W with contact force monitoring was used (Conventional group). We performed esophagogastroduodenoscopy after PVI in all patients and investigated the incidence and characteristics of ETI. Results - Although the incidence of ETI was significantly higher in the HP-SD group compared to the Conventional group (37% vs. 22%, P = 0.011), the prevalence of esophageal lesions did not differ between the groups (7% vs. 8%). Multivariate logistic regression analysis revealed that the use of the HP-SD setting (odds ratio: 6.09, P < 0.001), and the parameters that suggest anatomical proximity surrounding the esophagus, were independent predictors of ETI. However, the majority of ETI in the HP-SD group was gastric hypomotility, and the thermal injury was limited to the shallow layer of the periesophageal wall using the HP-SD setting. Conclusions - Although the use of the HP-SD setting was a strong predictor of ETI, it could avoid deeper thermal injuries that reach the esophageal mucosal layer.

Using data from a multicenter study that included 144 patients undergoing an electrophysiological study of left FVT, we identified 13 patients (9%) in whom sustained FVT was successfully eliminated by ablation of the Purkinje potentials around the posterior PM (n=8; PPM-FVT) and anterior PM (n=5; APM-FVT). Patients © 2017 American Heart Association, Inc. Original ArticleBackground-Verapamil-sensitive fascicular ventricular tachycardia (FVT) has been demonstrated to be a reentrant mechanism using the Purkinje network as a part of its reentrant circuit. Although the papillary muscles (PMs) are implicated in arrhythmogenic structure, reentrant FVT originating from the PMs has not been well defined. Methods and Results-We studied 13 patients in whom FVT was successfully eliminated by ablation at the posterior PMs (n=8; PPM-FVT) and anterior PMs (n=5; APM-FVT). Although intravenous administration of verapamil (5 mg) terminated ventricular tachycardia (VT) in 6 patients, VT was only slowed in the remaining 7 patients. PPM-FVT exhibited right bundle branch block and superior right axis (extreme right axis) or horizontal axis deviation. APM-FVT exhibited right bundle branch block configuration and right axis deviation with deep S wave in leads I, V 5 , and V 6 . VT was reproducibly induced by programmed atrial or ventricular stimulation. His-ventricular interval during VT was shorter than that during sinus rhythm. Ablation at the left posterior or anterior fascicular regions often changed the QRS morphology but did not completely eliminate it. Mid-diastolic Purkinje potentials were recorded during VT around the PMs, where ablation successfully eliminated the tachycardia. All patients have been free from recurrent VT after ablation. Conclusions-Reentrant circuit of verapamil-sensitive FVT can involve the Purkinje network lying around the PMs. PM-FVT is a distinct entity that is characterized by distinctive electrocardiographic characteristics and less sensitivity to verapamil administration compared with common type FVT. Ablation targeting the mid-diastolic Purkinje potentials around the PMs during tachycardia can be effective in suppressing this arrhythmia. (Circ Arrhythm Electrophysiol.