Author: Anna Hartzog, MD and Chinwe Unegbu, MD – Children’s National Hospital


A two-week-old neonate with double-outlet right ventricle, ventricular septal defect, L-looping of the ventricles, and levo-transposition of the great arteries is status post complete repair. On postoperative day twelve during a cardiac catheterization, the patient converts from normal sinus rhythm to complete heart block with a ventricular escape rate of 80 beats per minute. What is the MOST LIKELY factor that predisposes this patient to complete heart block?