The arterial switch operation is now recognized as the procedure of choice for treatment of infants and children born with the combination of concordant atrioventricular and discordant ventriculo-arterial connections, usually known simply as transposition. Although the Mustard and Senning atrial switch procedures achieved widespread acceptance and success, the accumulating observations at mid- to late follow-up of, first, the increasing frequency of arrhythmias and sudden death, second, late right ventricular dysfunction and severe tricuspid regurgitation and, third, high operative mortality in such patients with ventricular septal defects, have led to the worldwide use of the arterial switch operation for both simple and complex forms of transposition.1