Anterograde His bundle activation during right ventricular overdrive pacing in supraventricular tachycardia.

BACKGROUND: Differentiation between atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular re-entrant tachycardia (AVRT), and atrial tachycardia (AT) is often challenging during electrophysiology studies. This study compared the sensitivity and specificity of identifying anterograde His bundle activation during entrainment with commonly used right ventricular (RV) pacing maneuvers to differentiate between these types of supraventricular tachycardia (SVT). METHODS: Out of 112 consecutive patients with SVT, 90 (36 males [40%], age 37 ± 16 years) were prospectively studied. After entrainment during RV pacing, atrial response upon cessation of pacing, anterograde His activation during entrainment, stimulus-atrial (SA), ventriculoatrial (VA) intervals, and post-pacing interval minus tachycardia cycle length (PPI-TCL) were determined. Ventricular extrastimulation during tachycardia and para-Hisian pacing were performed. RESULTS: The final diagnosis was AVNRT in 54, AVRT in 33, and AT in 3 patients. Entrainment was achieved in 87(96%) patients. Anterograde His bundle activation predicted AVRT (sensitivity: 62.5%, specificity: 100%). PPI-TCL ≥129 ms predicted AVNRT (sensitivity: 83%, specificity: 84%), as did SA-VA value ≥85 ms (sensitivity: 91%, specificity: 87%). Atria were advanced during transition zone in 57% of AVRTs. Atrial pre-excitation in response to progressively premature ventricular extrastimuli identified AVRT (sensitivity: 90%, specificity: 85%). Pre-excitation index ≥87 ms identified AVNRT (sensitivity: 80%, specificity: 100%). Para-Hisian pacing identified AVRT (sensitivity: 25%, specificity: 100%). CONCLUSION: RV pacing maneuvers, applied in isolation, can misclassify a significant proportion of SVTs. Identifying anterograde His bundle activation during entrainment can complement other discriminators in differential diagnosis of SVT, with greatest sensitivity in septal and right-sided accessory pathways.

Endocardial ablation of ventricular ectopic beats arising from the basal inferoseptal process of the left ventricle.

BACKGROUND: Idiopathic ventricular ectopy (VE) shows predilection to sites within the left ventricular (LV) base such as the outflow tract/aortic sinuses, LV summit, and areas adjacent to the aortomitral continuity. We characterize VE arising from the inferior septum of the LV base that was successfully managed by LV endocardial ablation from the inferoseptal recess of the LV. OBJECTIVE: The purpose of this study was to determine the incidence, electrocardiographic (ECG) findings, electrophysiological findings, and anatomical features associated with VE arising from the basal inferoseptal process of the LV (ISP-LV) ablated using an LV endocardial approach via the inferoseptal recess of the LV. METHODS: A total of 425 consecutive patients undergoing VE ablation between January 1, 2012 and December 31, 2016 at 3 centers were evaluated. Demographic characteristics, ECG findings, and procedural data were analyzed for patients with ISP-LV VEs. RESULTS: Seven (1.5%) had a site of origin from the ISP-LV. Common ECG findings were a right bundle branch block concordant pattern or an atypical left bundle branch block early transition pattern, suggestive of a basal origin with a left superior axis, a biphasic QRS complex in lead aVR, and a small s wave in lead V6. Earliest activation was seen in an area below the outflow tract accessed from the inferoseptal recess inferior to the His bundle. In 3 cases, transient junctional rhythm was seen during ablation. All cases were ablated successfully with no complications. CONCLUSION: VE arising from the ISP-LV represents a distinct subset of idiopathic arrhythmia and can be successfully treated by endocardial catheter ablation from the inferoseptal recess. They share common surface ECG and electrophysiological findings with special anatomical features that need recognition for successful catheter ablation.

Left atrium in cardiac resynchronization therapy: Active participant or innocent bystander.

BACKGROUND: Cardiac resynchronization therapy (CRT) is an established treatment for patients with advanced heart failure that results in improvement of left ventricle (LV) systolic function and LV reverse remodeling. This may have a positive effect on the size and the function of the left atrium (LA). We assessed the LA function, dimensions, and volumes before and after CRT implantation. METHODS: A total of 37 patients with mean age of 55.3 ± 9.64 years including 11 (29.7%) females, having symptomatic heart failure [ejection fraction (EF) <35%, left bundle branch block >120 ms, with New York Heart Association III or ambulatory class IV] were enrolled, and underwent CRT implantation. M-mode, two-dimensional (2D) echocardiography, tissue Doppler imaging, and 2D strain (ɛ) imaging were done assessing LV volumes, ejection fraction, and diastolic function, LA diameter, area, maximal and minimal volumes, LA EF, and longitudinal strain (ɛ). Patients were reassessed after 3 months. A reduction in LV end-systolic volume of ≥10% was defined as volumetric responders to CRT. Patients with decompensated New York Heart Association class IV, sustained atrial arrhythmias, rheumatic or congenital heart diseases, nonleft bundle branch block, and those who were poorly echogenic, were excluded. RESULTS: Twenty-four (64.8%) patients were volumetric responders (group A). Both groups were matched regarding demographic, clinical, electrocardiographic, and echocardiographic criteria apart from the LA dimension and volumes which were significantly lower in the responders group prior to CRT. At the end of the follow-up, only the responders group had further significant reduction in LA diameter (41.6 ± 1.67 vs. 43.88 ± 1.82 mm, p < 0.01), maximal volume (62.2 ± 18.3 vs. 73.04 ± 21.78 ml, p < 0.01), minimal volume (32.6 ± 12.3 vs. 41.8 ± 13.97, p < 0.01), together with a significant increase in LA EF (48.3 ± 11.3 vs. 41.99 ± 13.9, p < 0.01), positive longitudinal strain (16.59% ± 5.89 vs. 12.45% ± 6.12, p < 0.01), and negative longitudinal strain (-3.3 ± 1.9 vs. -1.62 ± 1.2, p < 0.01) compared to baseline readings, a finding that was not present in the nonresponders group. In addition, atrial fibrillation was significantly higher in the nonresponders group. Baseline LA diameter and volumes were found to be independent predictors of response to CRT by multivariate analysis. CONCLUSIONS: CRT induces LA anatomic, electrical, and structural reverse remodeling that could be assessed by conventional 2D echocardiography and 2D (ɛ) strain imaging. LA dimension and volumes were independent predictors of response to CRT and can help in selection of candidates for it.

Predictors of success in ablation of scar-related ventricular tachycardia.

During ablation of re-entrant ventricular tachycardia (VT) 3-dimensional mapping systems are now used to properly delineate the scar tissue and aid ablation of scar-related VT. The aim of our study was to outline how the mode of ablation predicts success and recurrence in large scar-related VT. When comparing patients with recurrence and patients with no recurrence, univariate analysis showed that number of ablation lesions (28 ± 8 vs. 12 ± 8, P = 0.01) and more linear ablation lesions rather than focal lesions (P = 0.03) were associated with long-term success. We demonstrated that more extensive ablation lesions and creation of linear lesions is associated with better success rate and lower recurrence rate during ablation of large scar-related ventricular tachycardia.