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

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.

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.

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.

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).

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.