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Related Experiment Video

Updated: Dec 15, 2025

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

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Published on: December 11, 2017

Defining Left Bundle Branch Block Patterns in Cardiac Resynchronisation Therapy: A Return to His Bundle Recordings.

Roderick Tung¹, Gaurav A Upadhyay¹

¹Center for Arrhythmia Care, Pritzker School of Medicine, University of Chicago, Chicago, IL, US.

Arrhythmia & Electrophysiology Review

|July 9, 2020

Summary

Left bundle branch block (LBBB) is often proximal, not diffuse. Left-sided His bundle pacing (HBP) effectively corrects QRS in these patients, improving cardiac resynchronisation therapy (CRT) selection.

Keywords:

Cardiac resynchronisation therapy His bundle biventricular pacing conduction block electrophysiology left bundle branch block septal activation

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Last Updated: Dec 15, 2025

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Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction

Published on: January 31, 2019

Area of Science:

Cardiology
Electrophysiology
Medical Devices

Background:

Left bundle branch block (LBBB) is linked to better outcomes with cardiac resynchronisation therapy (CRT).
Traditionally, LBBB was thought to stem from widespread distal conduction system disease.
His bundle pacing (HBP) can normalize wide QRS, challenging traditional LBBB pathophysiology assumptions.

Purpose of the Study:

To investigate the location of conduction block in patients with LBBB.
To determine if the location of block predicts response to His bundle pacing (HBP) for resynchronisation.
To refine patient selection for cardiac resynchronisation therapy (CRT).

Main Methods:

Utilised an extended invasive electrophysiology study (EPS) with left-sided recordings.
Assessed conduction block in patients with LBBB pattern.
Correlated QRS correction with HBP to the site of conduction block.

Main Results:

Conduction block in LBBB is typically proximal, often in left-sided His fibres.
Patients with proximal block showed the greatest QRS correction with HBP.
Intact Purkinje activation or intraventricular conduction delay predicted less benefit from HBP.

Conclusions:

LBBB pathophysiology often involves proximal conduction block.
Left-sided EPS can identify patients likely to benefit from HBP for CRT.
This approach may improve patient selection for CRT and phenotyping conduction disorders.