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Effect of His bundle pacing on right bundle branch block located distal to site of pacing

Rehan Mahmud1, Shakeel Jamal1

  • 1McLaren Bay Region, 1900 Columbus Ave, Bay City, MI 48708, USA.

Journal of Electrocardiology
|December 20, 2020
PubMed

Insights

Non-selective His bundle pacing (NS-HBP) can correct right bundle branch block (RBBB), even when the block is distal to the pacing site. Higher pacing voltages and lower capture thresholds during NS-HBP improve RBBB correction, suggesting parallel pathway conduction.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Devices

Background:

  • Bundle branch block (BBB) is often corrected by selective His bundle pacing (S-HBP) distal to the block.
  • Clinical His bundle pacing (HBP) is frequently non-selective (NS-HBP), with unknown block sites and lead repositioning limitations.
  • The mechanism of RBBB correction in NS-HBP remains unclear.

Purpose of the Study:

  • To investigate the mechanism of right bundle branch block (RBBB) correction during non-selective His bundle pacing (NS-HBP).
  • To compare the efficacy of NS-HBP versus selective His bundle pacing (S-HBP) in correcting RBBB.
  • To analyze the influence of pacing voltage and capture threshold on RBBB correction.

Main Methods:

  • Conducted threshold testing during His bundle pacing in 39 patients with RBBB.
  • Compared outcomes between NS-HBP and S-HBP.
  • Analyzed the role of pacing voltage and capture threshold in RBBB correction.

Main Results:

  • Higher pacing voltage during NS-HBP completely corrected RBBB in 22/35 patients, versus 5/18 at lower voltage.
  • NS-HBP with a lower capture threshold (1.3 ± 0.5 V) resolved RBBB in 9/14 patients, compared to 3/11 with a higher threshold (2.4 ± 0.8 V) in the NS-S HBP group.
  • S-HBP resolved RBBB in only 1/21 patients, while NS-HBP showed QRS duration of 91 ± 8 ms (baseline 97 ± 7 ms).

Conclusions:

  • Lack of S-HBP correction suggests RBBB was distal to the pacing site, yet corrected by NS-HBP.
  • Voltage-dependent RBBB correction in NS-HBP indicates conduction via a parallel pathway normalizes ventricular activation.
  • Correction of RBBB in all NS-HBP patients suggests the block was bypassed or the RV free wall was pre-excited via a parallel pathway.
Abstract

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