Implementation of Intraoperative Conduction Mapping to Avoid Postoperative Complete Atrioventricular Block During Surgery of Congenital Heart Defects

All articles of this category (opens in new window) Background: Surgery for congenital heart defects (CHD) often involves cutting and sewing in close proximity to the atrioventricular node and the distal cardiac conduction system (CCS), which can result in advertent postoperative atrioventricular block (AVB) requiring permanent pacemaker stimulation. In about 1 to 3% of all surgical procedures in CHD, a postoperative AVB occurs and reaches up to 15 to 25% in very complex CHD, including heterotaxy syndromes. The necessity of permanent pacemaker stimulation is known to increase morbidity and mortality and needs to be avoided, especially in this complex patient cohort. Methods: Intraoperative conduction mapping (IOM) was done with a high-density multielectrode grid catheter, which was connected to a mobile electrophysiology recording unit. Preoperatively, the surface ECG, the anatomical and embryological background, was evaluated to roughly anticipate the position of the His bundle. In accordance, the catheter was placed in the open, beating heart during the surgical procedure. The local electrograms were interpreted and communicated to the surgeon. The position of the conduction axis was identified and implemented into the surgical strategy in order to avoid AVB. This prestudy presents the results of a 3-month test phase carried out in 2025, representing, to our knowledge, the first IOM performed in Germany. The primary outcome of the test phase is the safety and feasibility of this technique. Results: Four patients were mapped successfully within the first half of the test phase. Further patients will be enrolled. Until now, there have been no severe complications, such as air embolism or death. No permanent postoperative AVB has been observed. Up to now, the IOM has prolonged the operation time by an average of 7 minutes. Conclusion: Our preliminary experience demonstrates that IOM can be performed safely during congenital heart surgery and has the potential to significantly lower the incidence of postoperative AVB. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany