Stimulation and propagation of activation in conduction tissue: Implications for left bundle branch area pacing.
Heart Rhythm 2021;
18:813-821. [PMID:
33418128 DOI:
10.1016/j.hrthm.2020.12.030]
[Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 11/21/2022]
Abstract
BACKGROUND
Characterizing wavefront generation and impulse conduction in left bundle (LB) has implications for left bundle branch area pacing (LBBAP).
OBJECTIVES
The purpose of this study was to describe the pacing characteristics of LB and to study the role of pacing pulse width (PW) in overcoming left bundle branch block.
METHODS
Twenty fresh ovine heart slabs containing well-developed and easily identifiable tissues of the conduction system were used for the study. LB stimulation, activation, and propagation were studied under baseline conditions, simulated conduction slowing, conduction block, and fascicular block.
RESULTS
The maximum radius of the LB early activation increased up to 13.4 ± 2.4 mm from the pacing stimulus, and the time from stimulus to evoked potential shortened when pacing PW was increased from 0.13 to 2 ms at baseline. Conduction slowing and block induced by cooling could be resolved by increasing pacing PW from 0.25 to 1.5 ms over a distance of 10 ± 1.5 mm from the pacing stimulus. The LB strength-duration (SD) curve was shifted to the left of the myocardial SD curve.
CONCLUSION
Increasing PW resolved conduction slowing and block and bypassed the experimental model of fascicular block in LB. Precise positioning of the LB lead in left ventricular subendocardium is not mandatory in LBBAP, as the SD curve of LB was shifted to the left of the myocardium SD curve and could be captured from a distance by optimizing PW.
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