Left bundle branch pacing in patients with right bundle branch block

Abstract

Background The paced morphology of right bundle branch block (RBBB) pattern is one of the parameters which can be used to confirm the left bundle branch capture during left bundle branch pacing (LBBP) implantation. However, changes of paced morphology after LBBP performed in patients with RBBB have not been well discussed. Objective To compare the paced morphology in patients with RBBB before and after LBBP and to discuss the possible mechanisms behind such changes. Methods Patients with RBBB who underwent LBBP implantation were selected. The QRS duration was measured before and after the implantation of LBBP for each patient and compared Student t test. Results We included 34 consecutive patients (median age 72.76 years, 73.53% male), of whom 3 had sick sinus syndrome (SSS) and 31 had high-grade atrioventricular conduction block (AVB). The average QRS duration was 144.87±5.22ms before LBBP implantation and 116.18±6.15ms after LBBP implantation, with a mean decrease in QRS duration of 28.70±3.30ms (95% CI: 27.55-29.85 ms, P < 0.01). Conclusion In patients with RBBB, the QRS duration after LBBP is narrower than that before LBBP. The specific mechanism is still unclear.

Early Assessment of Ventricular Synchronization and Function After Left Bundle-Branch-Area Pacing with Right Bundle-Branch Block

“…Left bundle-branch-area pacing (LBBAP) is a kind of physiological pacing with a low and stable pacing threshold [1]. After LBBAP, the patient's ECG often shows a complete or an incomplete right bundle-branch block (RBBB) pattern [2,3]. After optimizing the atrioventricular interval, right bundle branch conduction can merge with the pacing signals, so that RBBB morphology can be eliminated.…”

“…However, for patients with intrinsic RBBB, the conduction of the right bundle branch is delayed or blocked. Although the duration of QRS after LBBAP is shorter than before, and the RBBB morphology of the electrocardiogram is improved [3,4], there is still a difference in the optimal atrioventricular interval between the RBBB and non-RBBB group [5]. On the premise of atrioventricular interval optimization, whether the right bundlebranch block will cause ventricular asynchrony and decline in ventricular function in RBBB patients after LBBAP has not been discussed yet.…”