Bilateral Bundle Branch Area Pacing to Achieve Physiological Conduction System Activation

Abstract

Background - Left bundle branch pacing (LBBP) is a technique for conduction system pacing, but it often results in right bundle branch block (RBBB) morphology on the electrocardiogram. This study was designed to assess simultaneous pacing of the left and right bundle branch areas to achieve more synchronous ventricular activation. Methods - In symptomatic bradycardia patients, the distal electrode of a bipolar pacing lead was placed at the left bundle branch area via a trans-ventricular septal approach. This was used to pace the left bundle branch area, while the ring electrode was used to pace the right bundle branch area. Bilateral bundle branch area pacing (BBBP) was achieved by stimulating the cathode and anode in various pacing configurations. QRS duration, delayed right ventricular activation time (dRVAT), left ventricular activation time (LVAT) and inter-ventricular conduction delay were measured. Pacing stability and short-term safety were assessed at three-month follow-up. Results - BBBP was successfully performed in 22 of 36 patients. Compared with LBBP, BBBP resulted in greater shortening of QRS duration (109.3±7.1 ms vs. 118.4±5.7 ms, P<0.001). LBBP resulted in a paced RBBB configuration, with a dRVAT of 115.0±7.5 ms and inter-ventricular conduction delay of 34.0±8.8 ms. BBBP fully resolved the RBBB morphology in 18 patients. In the remaining 4 patients, BBBP partially corrected the RBBB with dRVAT decreasing from 120.5±4.7 ms during LBBP to 106.1±4.2 ms during BBBP (P=0.005). Conclusions - LBBP results in a relatively narrow QRS complex, but with an inter-ventricular activation delay. BBBP can diminish the delayed right ventricular activation, producing more physiological ventricular activation.

Left bundle branch pacing in heart failure patients with left bundle branch block: A systematic review and meta‐analysis

“…The reason may be that when LBBP paces the left conduction system, the impulse is rapidly retrograde along HIS to the right bundle branch, 17–19 and slowly transversely across the interventricular septum to the right bundle branch 20 . Recently, Chen et al 21 . reported bilateral bundle branch pacing (BBBP), the results showed that BBBP could achieve more synchronous ventricular activation than LBBP, but its efficacy and safety needed to be further studied.…”

Left bundle branch pacing for cardiac resynchronization therapy: A systematic literature review and meta‐analysis

“…One of specific features of LBBP are right bundle branch block (RBBB) paced QRS morphology, which may have an effect on right ventricular conduction and adverse consequences. However, RBBB could be eliminated by adjusting AV delay 9 (fused with intrinsic activation from the right bundle branch), combination with left ventricular epicardial pacing or bilateral bundle branch area pacing 25 (the potentiality of the ring electrode capture on the right side of the interventricular septum, the transverse interconnections, 26 or virtual field stimulation 27,28 ). Second, due to deep position in the basal interventricular septum of the pacing lead, there are some concerns about LBBP: (1) coronary artery damage 29,30 ; (2) lead stability affected by constant contraction of septal myocardium; (3) progress of hypertrophic and fibrotic interventricular septum which may preclude the successful capture of LBBP.…”

The Physiologic Mechanisms of Paced QRS Narrowing During Left Bundle Branch Pacing in Right Bundle Branch Block Patients

“…Several other studies have also suggested that LBBP might be a viable choice to correct the RBBB ( 24 , 25 ). Lin et al ( 26 ) employed unipolar LBBP to shorten the RBBB duration from 137.7 ± 19.2 ms to 118.7 ± 6.7 ms, and bipolar LBBP to shorten the RBBB duration even further to 105.0 ± 5.0 ms, eliminating interventricular conduction delay. Previous studies have also shown that LBBP can shorten the QRS duration of intrinsic RBBB by about 30ms ( 27 ), as summarized in Table 1 .…”