Guidance on left bundle branch pacing using continuous pacing technique and changes in lead V1 characteristics under real-time monitoring

Background

The changes in the morphology and characteristics of the V1 leads during left bundle branch capturing still need to be fully understood.

Objective

This study aims to provide some suggestions about the LBB capture process through the morphology and characteristics of the V1 lead.

Method

LBBP using the continuous pacing and morphology monitoring technique during screw-in using a revolving connector (John Jiang's connecting cable). The morphology and features of V1 leads are recorded by continuous monitoring technology.

Results

The most common morphology in the LVSP stage is QR, while in the NS-LBBP (low output) stage and the NS-LBBP (lower output) stage, it is rSR. In the S-LBBP stage, it is rsR. The predominant morphology is with r/R waves in S-LBBP, which includes variations like rSR, rsR, rSr, rsr, rR, rs, rS, and R type, making up 96.7% of the total. The r waves in lead V1 are associated with agitated myocardium conducted from the left bundle branch.

Conclusion

The initial r-wave in lead V1 may be a marker during the follow-up of patients with selective LBB capture.

Redefining QRS transition to confirm left bundle branch capture during left bundle branch area pacing

Background

QRS transition criteria during dynamic manoeuvers are the gold-standard for non-invasive confirmation of left bundle branch (LBB) capture, but they are seen in <50% of LBB area pacing (LBBAP) procedures.

Objective

We hypothesized that transition from left ventricular septal pacing (LVSP) to LBB pacing (LBBP), when observed during lead penetration into the deep interventricular septum (IVS) with interrupted pacemapping, can suggest LBB capture.

Methods

QRS transition during lead screwing-in was defined as shortening of paced V6-R wave peak time (RWPT) by ≥10 ms from LVSP to non-selective LBBP (ns-LBBP) obtained during mid to deep septal lead progression at the same target area, between two consecutive pacing manoeuvres. ECG-based criteria were used to compared LVSP and ns-LBBP morphologies obtained by interrupted pacemapping.

Results

Sixty patients with demonstrated transition from LVSP to ns-LBBP during dynamic manoeuvers were compared to 44 patients with the same transition during lead screwing-in. Average shortening in paced V6-RWPT was similar among study groups (17.3 ± 6.8 ms vs. 18.8 ± 4.9 ms for transition during dynamic manoeuvres and lead screwing-in, respectively; p = 0.719). Paced V6-RWPT and aVL-RWPT, V6-V1 interpeak interval and the recently described LBBP score, were also similar for ns-LBBP morphologies in both groups. LVSP morphologies showed longer V6-RWPT and aVL-RWPT, shorter V6-V1 interpeak interval and lower LBBP score punctuation, without differences among the two QRS transition groups. V6-RWPT < 75 ms or V6-V1 interpeak interval > 44 ms criterion was more frequently achieved in ns-LBBP morphologies obtained during lead screwing-in compared to those obtained during dynamic manoeuvres (70.5% vs. 50%, respectively p = 0.036).

Conclusions

During LBBAP procedure, QRS transition from LVSP to ns-LBBP can be observed as the lead penetrates deep into the IVS with interrupted pacemapping. Shortening of at least 10 ms in paced V6-RWPT may serve as marker of LBB capture.

Achievement rate and learning curve of left bundle branch capture in left bundle branch area pacing procedure performed to demonstrate output-dependent QRS transition

INTRODUCTION

Recently, output-dependent QRS transition was reported to be required to confirm left bundle branch (LBB) capture in LBB area pacing (LBBAP) procedure. This study aimed to evaluate the achievement rate and the learning curve of LBB capture in LBBAP procedure performed with the goal of demonstrating output-dependent QRS transition, and investigate predictors of LBB capture.

METHODS AND RESULTS

The LBBAP procedure was performed in 126 patients with bradyarrhythmia. LBB capture was defined as a demonstration of output-dependent QRS transition. The following pacing definitions were used for evaluation: a) LBBAP, which met the previously reported LBBAP criteria, b) LBB pacing (LBBP), LBB capture was confirmed, and c) available LBBP, LBB threshold was clinically usable (<3 V at 0.4 ms). The learning curve was evaluated by division into three time-periods. The achievement rates of LBBAP, LBBP, and available LBBP were 88.1%, 41.2%, and 35.7%, respectively. The achievement rates of all three pacing definitions significantly increased with experience (p < 0.01), but the achievement rate of available LBBP was still 50% in the third period. As predictors of LBB capture, the interval between LBB-Purkinje potential and QRS onset ≥22 ms had high specificity of 98.3%, while R wave peak time in V6 <68 ms had insufficient sensitivity of 79% and specificity of 68%.

CONCLUSION

Even if LBB capture was aimed in LBBAP procedure, it was not easy to achieve, and there was a clear learning curve. Much of LBBAP may be left ventricular septal pacing that does not capture LBB. This article is protected by copyright. All rights reserved.