FATE OF SMALL HOMOGRAFT CONDUITS AFTER EARLY REPAIR OF TRUNCUS ARTERIOSUS

Neonatal repair of truncus arteriosus is being performed in a number o f centers, often with the use of small homograft conduits. The fate of the homograft and the risk of replacement were the subjects of this s tudy. Between January 1987 and October 1991, 43 infants aged less than 3 months (range, 3 to 90 days) underwent primary repair of truncus ar teriosus including implantation of a valved homograft conduit (diamete r, 7 to 12 mm). Twenty-nine had follow-up of more than 6 months (range , 6 to 65 months; mean, 21.9 months). After a mean period of 31 months (range, 8 to 65 months), 7 patients showed obstruction with right ven tricular pressures at least 75% systemic and underwent either a condui t change (n = 5) or a patch augmentation (n = 2). Mean cardiopulmonary bypass time at reoperation was 99 minutes; mortality was zero. Five o ther children are known to have a right ventricular pressure of 50% to 60% systemic, 2 having undergone balloon dilation. Statistical compar ison of the patients with conduit reoperation or high right ventricula r pressure (n = 12) with the rest of the population (n = 17) revealed an elevated pulmonary artery to right ventricular pullback gradient on postoperative day 1 after the repair (7.7 versus 1.3 mm Hg; p = 0.001 ) and choice of an aortic over a pulmonary homograft (100% versus 64.7 %; p = 0.065) as significant risk factors. Age and weight at repair, p ostoperative pulmonary artery pressure, length of follow-up, and size of the homograft showed no significant differences between the two gro ups. A postoperative pulmonary artery to right ventricular pressure gr adient is a risk factor for conduit replacement within 2 years, possib ly reflecting subtle technical factors or small branch pulmonary arter ies. Very small homografts (7 to 9 mm in diameter) are not, but, most interestingly, aortic homografts are a significant risk factor for ear ly replacement. The use of small pulmonary homografts should be encour aged.