Novel Strategy for Predicting Conduction Abnormalities During Transcatheter Closure of Perimembranous Ventricular Septal Defect in Adults.

BACKGROUND: In this study we evaluated the feasibility and efficacy of predicting conduction system abnormalities under 3-dimensional (3D) electroanatomic mapping guidance during transcatheter closure of perimembranous ventricular septal defects (pmVSDs) in adults.Methods and Results:The distribution of the His-Purkinje system (HPS) close to the margins of pmVSDs in the left ventricle was identified using 3D electroanatomic mapping and near-field HPS was further confirmed by different pacing protocols. Of the 20 patients in the study, 17 (85%) were successfully treated by transcatheter intervention. The minimum distance between the margins of the pmVSD and near-field HPS, as measured by 3D electroanatomic mapping, ranged from 1.3 to 3.9 mm (mean [± SD] 2.5±0.7 mm). Five patients with a minimum distance <2 mm had a higher risk (3/5; 60%) for adverse arrhythmic events, whereas patients with a distance >2 mm were at a much lower risk (1/15; 6.7%) of procedure-related conduction block (P=0.032). No other adverse events were recorded during the follow-up period (median 30 months). CONCLUSIONS: A minimum distance between the pmVSD and near-field HPS <2 mm was associated with a relatively high risk of closure-related conduction block. 3D electroanatomic mapping may be helpful in guiding decision making for transcatheter closure and reduce the incidence of adverse arrhythmic events.

Inability to capture with increasing current strength: Is this near-field or far-field?

We present a case of wide-complex tachycardia in which the clinical electrophysiological diagnosis was considered to be bundle branch re-entry ventricular tachycardia. A series of ventricular entrainment attempts were performed from the left and right ventricular septum to confirm the diagnosis. Entrainment pacing with a general current output (10 mA) was performed from the right ventricular septum with manifest fusion and a post-pacing interval similar to tachycardia cycle length. Thereafter, another entrainment attempt with a greater current output (20 mA) was performed from the same site. Paradoxically, concealed fusion was demonstrated by selective RB capture only, though there was no clear "RB" potential seen. In this case, we attempt to explain and illustrate the mechanism of paradoxical near-field inability to capture with increasing current strength.

Unique electrocardiographic pattern "w" wave in lead I of idiopathic ventricular arrhythmias arising from the distal great cardiac vein.

BACKGROUND: The ECG characteristics of the distal coronary venous system ventricular arrhythmias (VAs) share common features with VAs arising from the aortic cusps or the endocardial left ventricular outflow tract (LVOT) beneath the cusps. The purpose of this study was to identify specific electrocardiographic and electrophysiological characteristics of VAs originating from the distal great cardiac vein (GCV). METHODS: Based on the successful ablation site, patients with idiopathic VAs from the distal GCV, left coronary cusp (LCC) or the subvalvular left ventricular outflow tract (LVOT) area were included in the present study. RESULTS: The final population consisted of 39 patients (35 males, mean age 51 ± 23 years). All VAs displayed a right bundle branch block (RBBB) morphology with inferior axis. Among these patients, 15 were successfully ablated at the GCV, 15 at the LCC and 9 at the subvalvular region. A "w" pattern in lead I was present in 12 out of 15 (80%) VAs originating from the distal GCV compared to none of VAs arising from the other two sites (p < 0.01). VAs with a GCV origin exhibited more commonly increased intrinsicoid deflection time, higher maximum deflection index and wider QRS duration compared to LCC and subvalvular sites (p < 0.05). Acceptable pace mapping at the successful ablation site was achieved in 10 patients. After an average of 36 ± 24 months follow up, 14 (93.3%) patients were free from VAs recurrence. CONCLUSION: A "w" pattern in lead I may distinguish distal GCV VAs from VAs arising from the LCC or the subvalvular region.

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

OBJECTIVES: This 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). BACKGROUND: Mapping and ablation of post-operative ATs following previous open-heart surgery is often challenging because the potential mechanisms remain incompletely understood. METHODS: Fifty-one consecutive patients underwent mapping and ablation of post-surgical ATs. RESULTS: A total of 64 ATs were identified, and the mechanism was macro re-entry in 58 of 63 (92.1%) ATs, focal in 4 ATs, 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. CONCLUSIONS: RA 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.

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.

A new electrophysiologic observation in patients with idiopathic left ventricular tachycardia.

BACKGROUND: In patients with idiopathic left ventricular tachycardia (ILVT), the arrhythmogenic substrate is poorly understood. OBJECTIVE: The purpose of this study was to elucidate the ILVT characteristics and outcome of radiofrequency catheter ablation in patients with ILVT. METHODS: Twenty-four patients with ILVT and 15 patients with left accessory pathways (control) underwent high-density mapping of the left His-Purkinje system during sinus rhythm (SR) using 3-dimensional electroanatomic mapping. RESULTS: Fragmented antegrade Purkinje potential (FAP) was represented at the left ventricular septum slightly inferoposterior to the left posterior fascicle (LPF) in 23 patients with ILVT. In control subjects, no FAPs could be recorded at the same region, FAPs were identified at the proximal portion of the LPF (4 patients) and at the distal LPF (1 patient). The finding of any FAPs in ILVT patients was significantly higher than that in control patients (23/24 vs 5/15, P < .01). Radiofrequency ablation at the area of FAP resulted in successful ablation in 23 patients with ILVT. No ILVT recurred during follow-up of 16.3 ± 7.2 months. CONCLUSION: In patients with ILVT, FAP located at the left ventricular septum slightly inferoposterior to the LPF is a novel finding using 3-dimensional electroanatomic mapping. The FAP may represent an arrhythmogenic substrate in ILVT and may be used for guiding successful ablation.

Features of accessory pathways in adult Ebstein's anomaly.

AIMS: The aim of the study was to describe the complex electrophysiological features of accessory pathways (APs) in adult Ebstein's anomaly (EA). METHODS AND RESULTS: We performed a retrospective study of 17 consecutive adult EA cases with APs who underwent electrophysiological study and radiofrequency catheter ablation (RFCA) from November 2011 to May 2013. There were a total of 24 atrioventricular reentrant tachycardias (AVRTs) due to 23 APs, including 20 (87.0%) non-decremental conducting, 2 (8.7%) decremental conducting, and 1 (4.3%) nodofascicular bundle. Six (6/17 = 35.3%) patients had two APs while others had only one. Twenty-one APs (91.3%) in 15 patients were manifested and 2 APs (8.7%) in 2 patients were concealed. Six APs (26.1%) were broad, while 17 APs (73.9%) were narrow in width. Two patients suffered from duodromic tachycardias mediated by two APs. Accessory pathways were mainly located on the posterior, posteroseptal, and posterolateral tricuspid annulus (TA). Right ventriculography confirmed that all APs were located on the anatomic TA. All the patients remained free from tachycardias during 11.9 ± 6.8 months of follow-up after RFCA. For the 15 patients with manifest APs, 10 patients' electrocardiograms (ECGs) after RFCA demonstrated morphologies of right bundle branch block, while 5 patients' ECGs were normal. CONCLUSIONS: Accessory pathways in EA are predominantly right-sided, manifest and localize to the lower half of the anatomic TA. A number of APs in EA have broad widths. The incidence of multiple APs is high in these patients and RFCA is effective.

Trans-subclavian approach for radiofrequency ablation of premature ventricular contractions originating from subtricuspid annulus: a case report.

BACKGROUND: Catheter ablation has been established as a curative treatment strategy for ventricular arrhythmias. The standard procedure of most ventricular arrhythmias originating from the right ventricle is performed via the femoral vein. However, a femoral vein access may not achieve a successful ablation in some patients. CASE PRESENTATION: We reported a case of a 29-year old patient with symptomatic premature ventricular contractions was referred for catheter ablation. Radiofrequency energy application at the earliest endocardial ventricular activation site via the right femoral vein could not eliminate the premature ventricular contractions. Epicardial mapping could not obtain an earlier ventricular activation when compared to the endocardial mapping, and at the earliest epicardial site could not provide an identical pace mapping. Finally, we redeployed the ablation catheter via the right subclavian vein by a long sheath. During mapping of the subvalvular area of the right ventricle, a site with a good pace mapping and early ventricular activation was found, and premature ventricular contractions were eliminated successfully. CONCLUSION: Ventricular arrhythmias originating from the subtricuspid annulus may be successfully abolished via a trans-subclavian approach and a long sheath. Although access via the right subclavian vein for mapping and ablation is an effective alternative, it is not a routine approach.