The etiologies of sudden cardiac death following the surgical treatment of congenital heart defects remain uncertain. A young patient with prior repair of partial anomalous pulmonary venous return is presented, in whom brief episodes of a supraventricular tachyarrhythmia (rate 170/min) were documented to result in ventricular fibrillation. This unusual sequence may represent a basis for unexplained sudden cardiac death in other patients following atrial surgical procedures for the treatment of congenital heart disease.