The Role of High-output His-bundle Pacing During Atrioventricular Node Ablation

Abstract

Atrioventricular (AV) junction ablation (AVJA) is an acceptable strategy to control the heart rate in atrial fibrillation (AF) with a high procedural success rate. However, a small subset of patients pose a technical challenge with the standard right-sided approach. High-output His-bundle pacing has been shown to help localize the His bundle in a difficult-to-ablate AV junction. We report a case series of patients with difficult-to-ablate AVJA and present strategies to troubleshoot them. In this small series of patients, we found that high-output His pacing can be an effective alternative for successfully localizing the AVJA site. In this series, we also observed that an inability to achieve His capture from the right side can predict failure of ablation using the standard right-sided approach and the consequent need for a left-sided approach.

Keywords: Anti-arrhythmic; His bundle; atrial fibrillation; atrioventricular junction; atrioventricular junction ablation.

Figure 1:

Intracardiac electrogram showing a very small His signal on the second and fourth beats.

Figure 2:

High-output His pacing produces a narrow QRS complex. As the output is decreased, there is a loss of the His capture (wide QRS complex). Subsequent ablation in these areas produced complete heart block.

Figure 3:

A and B: The yellow-tagged areas correspond to the areas where high-output pacing produced direct His capture (narrow QRS). Ablation in the blue-tagged area proximal and posterior to the presumed His area produced complete heart block as is suggested by a paced QRS complex.

Figure 4:

Three-dimensional electroanatomic map showing the right atrium, tricuspid valve, aortic root, and ascending aorta. Multiple ablations from the right side failed to achieve heart block as can be seen by multiple ablation tags from the right side.

Figure 5:

Successful site of ablation below the non-coronary cusp with a His bundle signal of the distal electrode (left panel) of the ablation catheter corresponding to the blue dot. A single burn (blue dot) produced complete heart block.