Xianzhang Zhan

Ventricular Arrhythmias Arising from the Left Ventricular Outflow Tract below the Aortic Sinus Cusps: Mapping and Catheter Ablation via Transseptal Approach and Electrocardiographic Characteristics

Background—Ventricular arrhythmias (VAs) originating from the anterosuperior left ventricular outflow tract (LVOT) represent a challenging location for catheter ablation. This study investigates mapping and ablation of VA from anterosuperior LVOT via a transseptal approach. Methods and Results—This study included 27 patients with symptomatic VA, of which 13 patients had previous failed ablations. LVOT endocardial 3-dimensional mapping via retrograde transaortic and antegrade transseptal approaches was performed. Previous ECG markers for procedure failure were analyzed. In all patients, earliest activation with low-amplitude potentials was identified at the anterosuperior LVOT 5.1±2.8 mm below the aortic cusp and preceded the QRS onset by 39.5±7.7 ms only via an antegrade transseptal approach using a reversed S curve. In all patients, pace mapping failed to demonstrate perfect QRS morphology match. The anatomic location was below the left coronary cusp in 16, below the left coronary cusp/right coronary cusp junction in 8, and below the right coronary cusp in 3 patients. Radiofrequency energy resulted in rapid disappearance of VAs in all patients. ECG analysis showed aVL/aVR Q-wave amplitude ratio >1.4 in 7, lead III/II R-wave amplitude ratio >1.1 in 10, and peak deflection index >0.6 in 11 patients. There were no complications or clinical VA recurrence during a mean follow-up of 8.4±2.5 months. Conclusions—The anterosuperior LVOT can be reached via a transseptal approach with a reversed S curve of the ablation catheter. The rapid effect from radiofrequency energy indicates that the VA is most likely located under the endocardium. Also, previous ECG markers for procedure failure need further investigation.

STABLE-SR (Electrophysiological Substrate Ablation in the Left Atrium During Sinus Rhythm) for the Treatment of Nonparoxysmal Atrial Fibrillation: A Prospective, Multicenter Randomized Clinical Trial

Background: Circumferential pulmonary vein isolation (CPVI) alone or combined with adjuvant substrate modifications is unsatisfactory for atrial fibrillation (AF) control in nonparoxysmal AF patients. Ablation targeting the fibrotic areas after CPVI (STABLE-SR [Electrophysiological Substrate Ablation in the Left Atrium During Sinus Rhythm]) is a newly evolved substrate modification strategy. Methods and Results: In this multicenter, randomized clinical trial, 229 symptomatic nonparoxysmal AF patients were 1:1 randomized to STABLE-SR group (n=114) or conventional STEPWISE group (n=115). In the STABLE-SR group, after CPVI, cavotricuspid isthmus ablation and cardioversion to sinus rhythm, left atrial high-density mapping was performed. Areas with low-voltage and complex electrogram were further homogenized and eliminated, respectively. Dechanneling would be done if necessary. In the STEPWISE group, additional linear lesions and defragmentation were performed.The primary end point was freedom from documented atrial tachyarrhythmias for ≥30 s after a single ablation procedure without antiarrhythmic medications at 18 months. At 18 months, 74.0% of the patients in the STABLE-SR group and 71.5% in the STEPWISE group (hazard ratio, 0.78; 95% confidence interval, 0.47–1.29; P=0.325) achieved success according to intention-to-treat analysis. However, less procedure time (186.8±52.7 versus 210.5±48.0 minutes, P<0.001), reduced post-CPVI fluoroscopic time (11.0±7.8 versus 13.7±8.9 minutes, P=0.006), and shorter energy delivery time (60.1±25.1 versus 75.0±24.3 minutes, P<0.001) were observed in the STABLE-SR group compared with the STEPWISE group. Conclusions: STABLE-SR is a simplified, personalized, and effective ablation strategy in nonparoxysmal AF patients. More importantly, over 50% nonparoxysmal AF patients do not need further ablation beyond CPVI and therefore can avoid excessive ablation. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01761188.

Experimental, Pathologic, and Clinical Findings of Radiofrequency Catheter Ablation of Para-Hisian Region From the Right Ventricle in Dogs and Humans

Background— Ablation of para-Hisian accessory pathway (AP) poses high risks of atrioventricular block. We developed a pacing technique to differentiate the near-field (NF) from far-field His activations to avoid the complication. Methods and Results— Three-dimensional mapping of the right ventricle was performed in 15 mongrel dogs and 23 patients with para-Hisian AP. Using different pacing outputs, the NF- and far-field His activation was identified on the ventricular aspect. Radiofrequency application was delivered at the NF His site in 8 (group 1) and the far-field His site in 7 dogs (group 2), followed by pathologic examination after 14 days. NF His activation was captured with 5 mA/1 ms in 10 and 10 mA/1 ms in 5 dogs. In group 1, radiofrequency delivery resulted in complete atrioventricular block in 3, right bundle branch block with HV (His-to-ventricular) interval prolongation in 1, and only right bundle branch block in 2 dogs, whereas no changes occurred in group 2. Pathologic examination in group-1 dogs showed complete or partial necrosis of the His bundle in 4 and complete necrosis of the right bundle branch in 5 dogs. In group 2, partial necrosis in the right bundle branch was found only in 1 dog. Using this pacing technique, the APs were 5.7±1.2 mm away from the His bundle located superiorly in 20 or inferiorly in 3 patients. All APs were successfully eliminated with 1 to 3 radiofrequency applications. No complications and recurrence occurred during a follow-up of 11.8±1.4 months. Conclusions— Differentiating the NF His from far-field His activations led to a high ablation success without atrioventricular block in para-Hisian AP patients.

Response to Letter from Yamada and Kay Regarding Article, “Ventricular Arrhythmias Arising From the Left Ventricular Outflow Tract Below the Aortic Sinus Cusps: Mapping and Catheter Ablation via Transseptal Approach and Electrocardiographic Characteristics” by Ouyang et al

We thank Drs Yamada and Kay for their comments regarding our article “Ventricular arrhythmias arising from the left ventricular outflow tract below the aortic sinus cusps: mapping and catheter ablation via transseptal approach and electrocardiographic characteristics.”1 The main issues raised by Drs Yamada and Kay focused around the transseptal approach used in our study to obtain better access to the area termed the LV summit.nnWe agree with the authors that using the retrograde aortic approach and with the catheter inversion technique, some of the regions beneath the aortic sinus cusps (ASC) can be reached. However, when this is performed with the 3D mapping system, one can see that in the majority of the time, there is a distance between …

Evaluation of Electrophysiological Mechanisms of Post-Surgical Atrial Tachycardias Using an Automated Ultra−High-Density Mapping System

OBJECTIVESnThis study aimed to evaluate the electrophysiological mechanisms of post-surgical atrial tachycardias (ATs) during mapping with an automated high-resolution mapping system (Rhythmia, Boston Scientific, Marlborough, Massachusetts).nnnBACKGROUNDnMapping and ablation of post-operative ATs following previous open-heart surgery is often challenging because the potential mechanisms remain incompletely understood.nnnMETHODSnFifty-one consecutive patients underwent mapping and ablation of post-surgical ATs.nnnRESULTSnA total of 64 ATs were identified, and the mechanism was macro re-entry in 58 of 63 (92.1%) ATs, focal in 4xa0ATs, localized micro re-entry in 1 AT, and undetermined in 1 AT. Of 11 patients who underwent surgical repair of congenital heart disease, 6 (54.5%) had peri-tricuspid re-entrant AT, 5 had either right atrial (RA) free-wall incisional ATs or figure-8 re-entrant ATs, with an isthmus between the tricuspid annulus and the RA free-wall incision or between the incisions, and none had left atrial (LA) or focal ATs. In 32 patients with valve replacement and 8 who underwent valvuloplasty, peri-tricuspid ATs were observed in 14 (43.4%) and 6 (75%) patients, RA free wall or septal incisions-related ATs were seen in 7 and 2 patients, and LA macro re-entrant ATs were observed in 12 patients and 1 patient, respectively. A macro pseudo re-entry pattern was identified in 8 of 51 patients (15.7%). All these activations could be easily excluded by manually moving the window of interest, except in 2 cases with a figure-8 re-entrant configuration.nnnCONCLUSIONSnRA macro re-entrant ATs predominate, irrespective of the types of initial surgical procedures, but LA ATs occur more frequently in patients with valve replacement. Pseudo re-entry atrial activation is common and easily recognized by adjusting the mapping window.

Reply: Cautionary Pulmonary Insufficiency in Ablation of Ventricular Arrhythmias From Pulmonary Sinus Cusps.

We thank Dr. Ren and colleagues for their interest in our article “Idiopathic Ventricular Arrhythmias Originating From the Pulmonary Sinus Cusp: Prevalence, Electrocardiographic/Electrophysiological Characteristics, and Catheter Ablation” [(1)][1]. The main issues raised by Dr. Ren and

The Small Cardiac Vein as an Unrecognized Substrate for Atrial Tachycardia

A 29-year-old Chinese male with palpitations was referred to our hospital. The 12-lead electrocardiography demonstrated incessant atrial tachycardia with negative P waves in leads V1 to V2 ([Figurexa01A][1]). The patient had twice undergone unsuccessful attempts at ablation of right atrial appendage