Impaired Atrioventricular Conduction System in a Postoperative Heart With Congenitally Corrected Transposition of the Great Arteries.

BACKGROUND: Twin atrioventricular nodes (AVNs) occasionally occur in congenitally corrected transposition of the great arteries (ccTGA). CASE SUMMARY: A 14-year-old adolescent girl with ccTGA died suddenly after cardiopulmonary arrest. The electrocardiogram showed QRS widening from age 6. At autopsy, a Rastelli conduit and a fibrotic scar from ventricular septal defect patch closure were present. Serial sections revealed isolated anterior and posterior AVNs. The posterior AVN continued into an elongated His bundle that was disrupted by fibrosis, whereas the anterior AVN was interrupted by fibrofatty tissue. DISCUSSION: QRS widening was likely caused by interruption of the elongated His bundle. Although posterior-dominant AVN is uncommon, it should be considered when planning surgery for ccTGA. TAKE-HOME MESSAGE: A posterior-dominant AVN is uncommon; however, it should be considered when planning surgery for ccTGA with usual atrial arrangement.