The Use of Valved Conduits in Pediatric Cardiac Surgery

Abstract

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%

Right Ventricle to Pulmonary Artery Reconstruction Using a Valved Homograft

“…13 In his review of articles on the early deterioration of valved homografts, Stark identified 3 risk factors: young age, small-sized homograft, and immunological response. 33 Recently, blood type mismatch has been thought to provoke the immunological response and result…”

Disfunção do homoenxerto pulmonar utilizado na reconstrução do trato de saída do ventrículo direito

“…In the majority of the cases, the deterioration of the homograft takes place by stenosis due to the calcification 1 . The rate of homograft failure varies as per the study, being in 5 years between 10.0-40.0% 5,14 of the implanted homografts and, in 10 years, between 46.0-65.0% 4,7 .…”

“…From the 80's, with the improvement of the techniques of preparation and conservation, the homograft became the chosen material in several services 1 . Despite this, the literature has still been showing the need for surgical changing due to the occurrence of stenosis or prosthesis insufficiency.…”

“…In the first years, the high calcification and stenosis rate of the graft caused the search for different combinations of materials for the reconstruction surgeries 1 .…”

The right ventricle in tetralogy of Fallot

“…Nevertheless, the ideal timing for pulmonary valve replacement remains unclear. The fact that the ideal graft for pulmonary valve replacement has not yet been found, and that the available grafts have a half-life of 10 years, needs to be borne in mind as a factor prompting caution when discussing pulmonary valve replacement [16].…”