The use of valved conduits in pediatric cardiac surgery.

Extracardiac valved conduits were introduced in 1966. Currently, both aortic and pulmonary homografts, preserved in antibiotic/nutrient solution or cryopreserved, are used. Conduits are implanted between the right ventricle and pulmonary artery, left ventricle and pulmonary artery, right atrium and right ventricle, and left atrium to left ventricle. Several factors can influence longevity of valved conduits: young age at implantation, small size of homograft, and immunological response. In the recent study from our department, we evaluated 405 homografts implanted between 1971 and 1993 in patients who survived 90 days after surgery. Freedom from conduit replacement at 5 and 15 years was 84% and 31% (95% confidence limits: 80-88% and 19-43%), respectively. In multivariate analysis, there were only two predictors of conduit longevity: (1) conduits used at reoperation lasted less well than those used at original operation; and (2) conduits used earlier in the series lasted longer. Conduits may have to be replaced because of obstruction, conduit valve regurgitation, aneurysm/pseudoaneurysm, and endocarditis. Obstructed conduits are either replaced or outflow tract patch is used after removal of the conduit with or without pulmonary valve implantation. Current mortality of conduit insertion is low (5-6%). The risk of conduit replacement has also decreased in recent years to 2-3.5%