Arterial switch operation for transposition of the great arteries, with special reference to left ventricular function.

Between June 1984 and September 1987, 48 patients underwent Lecompte's modification of the arterial switch operation for transposition of the great arteries, including transposition with intact ventricular septum with preparatory pulmonary artery banding (n = 18), with patent ductus arteriosus (n = 11), with dynamic left ventricular outflow tract obstruction (n = 4), and transposition with ventricular septal defect (n = 15). Ages ranged from 12 days to 36 months (mean 8 months) and weights ranged from 2.7 to 12.8 kg (mean 5.7 kg). Two deaths occurred, yielding an operative mortality rate of 4.2%. Preparatory pulmonary artery banding resulted in an increase to 65 +/- 5 mm Hg in the left ventricular afterload. Linear regression of the optimum circumference of the band (Y, millimeters) against left ventricular end-diastolic volume (X, milliliters) yielded the following formula: Y = 0.23X + 19.7 (r = 0.885, p less than 0.001). Influence of left ventricular mass on cardiac function after anatomic correction was evaluated. The total amount of dopamine used after repair in patients in whom the left ventricular mass was less than 60% of normal was significantly larger than that in patients with a left ventricular mass greater than or equal to 60% of normal (p less than 0.002). The left ventricular end-diastolic volume in patients with a left ventricular mass less than 60% of normal increased significantly 2 months after operation (p less than 0.05), whereas it decreased in patients with a left ventricular mass greater than 60% of normal (p less than 0.01). We believe it is safe to perform this procedure in patients in whom the left ventricular mass is larger than 60% of normal. Most newborn infants with simple transposition can undergo correction between 10 and 20 days of life if the ductus arteriosus is kept patent with prostaglandin E1 and the left ventricle is thereby loaded. Preparatory pulmonary artery banding, when necessary, will be satisfactory if the left ventricular pressure is greater than 65 mm Hg and/or the left ventricular/right ventricular pressure ratio is greater than 0.8.