Fate of small homograft conduits after early repair of truncus arteriosus

Abstract

Neonatal repair of truncus arteriosus is being performed in a number of centers, often with the use of small homograft conduits. The fate of the homograft and the risk of replacement were the subjects of this study. Between January 1987 and October 1991, 43 infants aged less than 3 months (range, 3 to 90 days) underwent primary repair of truncus arteriosus including implantation of a valved homograft conduit (diameter, 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 ventricular pressures at least 75% systemic and underwent either a conduit change (n = 5) or a patch augmentation (n = 2). Mean cardiopulmonary bypass time at reoperation was 99 minutes; mortality was zero. Five other children are known to have a right ventricular pressure of 50% to 60% systemic, 2 having undergone balloon dilation. Statistical comparison of the patients with conduit reoperation or high right ventricular 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, postoperative pulmonary artery pressure, length of follow-up, and size of the homograft showed no significant differences between the two groups. A postoperative pulmonary artery to right ventricular pressure gradient is a risk factor for conduit replacement within 2 years, possibly reflecting subtle technical factors or small branch pulmonary arteries. Very small homografts (7 to 9 mm in diameter) are not, but, most interestingly, aortic homografts are a significant risk factor for early replacement. The use of small pulmonary homografts should be encouraged.