Intraoperative Conduction Mapping to Reduce Postoperative Atrioventricular Block in Complex Congenital Heart Disease.

Background: Postoperative atrioventricular block requiring pacemaker (AVB/PM) complicates 14% to 25% of biventricular repair operations for complex congenital heart disease (CHD) and in those with heterotaxy syndrome.

Objectives: This study aimed to evaluate if intraoperative His bundle (HB) mapping during complex biventricular CHD repair can be performed safely and reduce postoperative AVB/PM.

Methods: HB mapping was performed using a commercially available multielectrode grid catheter in patients with complex CHD undergoing biventricular repair between 2019 and 2022 compared with an unmapped cohort. The primary outcome was postoperative AVB/PM.

Results: One hundred forty-nine patients underwent HB mapping compared to 201 unmapped controls. The median age of mapped patients was 1.9 years (Q1-Q3: 0.9-3.9 years). Heterotaxy syndrome was present in 31% (n = 46 of 149), ventricular septal defect in 95% (n = 142 of 149), and prior single ventricle palliation in 68% (n = 89 of 149). The HB was identified in 97% (n = 144 of 149) of cases. The median mapping time was 6 minutes. No episodes of intraoperative systemic air embolism occurred. Postoperative AVB/PM frequency was significantly reduced in mapped patients with heterotaxy (2% [n = 1 of 46] vs 16% [n = 11 of 67]; P = 0.026) and in patients without L-malposed great arteries (3% [n = 3 of 88] vs 11% [n = 15 of 134]; P = 0.045).

Conclusions: Intraoperative HB mapping can be performed safely and is associated with significantly reduced postoperative AVB/PM in select populations undergoing complex biventricular repair, including heterotaxy syndrome and non-L-malposed great arteries. Nonetheless, certain subgroups remain at risk for AVB/PM, showing the need for further improvements to current intraoperative HB mapping technology and techniques.