Late reoperations after neonatal arterial switch operation for transposition of the great arteries.

The arterial switch operation has become the treatment of choice for neonates with transposition of the great arteries. Currently, the early mortality rate is low as well as the need for early reoperation because of surgical failures; in our experience with 803 neonates, these risks were 3.8% and 1.5%, respectively. The late outcome in terms of survival and functional status is excellent. However, surgical repair is far from anatomical and potential late defects were identified as soon as this procedure was introduced: obstruction of the neo-pulmonary outflow tract, development of obstructions of the reimplanted coronary arteries, dysfunction of the neo-aortic valve, and progressive left ventricular dysfunction. Actually, late reoperations are required in 5-10% of patients (4.5% in our experience with a mean follow-up of 5.8 years). The more frequent indications for reoperation are coronary lesions and right ventricular outflow tract obstructions. Coronary obstructions are, in most cases, detected in patients without any clinical or echocardiographic evidence of myocardial ischaemia. Coronary lesions are progressive and repeated coronary evaluation at regular intervals is necessary. Reoperation is indicated when myocardial ischaemia, at rest or under stress, is demonstrated at myocardial imaging. Satisfactory results can be achieved by surgical coronary patch angioplasty; in selected cases, mammary bypass may be necessary. Right ventricular outflow tract obstruction is related either to inadequate growth of the pulmonary anastomotic site, or to inadequate growth of the whole new right ventricular outflow tract in patients with associated aortic arch obstruction. Reoperation is indicated when significant obstruction (gradient >50 mmHg) is detected at routine echo-Doppler evaluation. Although neo-aortic root dilation and minimal aortic valve insufficiency are common, reoperation for severe neo-aortic valve dysfunction is, to date, very rarely necessary. Whether this will remain the case in the decades to come requires further evaluation. Left ventricular function is maintained in the vast majority of patients. Reoperation may be indicated in some patients for other reasons: mitral valve malformation, tracheo-bronchial compression or pulmonary hypertension.