Inducible polymorphous ventricular tachycardia following Mustard operation for transposition of the great arteries.

A 22-year-old woman with chronic atrial tachycardia following Mustard's operation for transposition of the great arteries presented with dizziness and ventricular tachycardia documented with dynamic 24-h electrocardiogram. During intracardiac electrophysiology study, programmed ventricular extrastimulation induced polymorphous ventricular tachycardia (torsades de pointes). This was prevented by intravenous administration of procainamide. We postulate that polymorphous ventricular tachycardia is a possible cause of death in patients with Mustard's operation. Postoperative electrophysiologic study may define those patients at risk to develop this potentially fatal arrhythmia.