Influence of sizing and subcoronary implantation technique on the function of porcine aortic homografts

Abstract

The function and longevity of the homograft aortic valve may be influenced by valve size and subcoronary implantation technique. Dynamic function and leaflet configuration of the porcine aortic valve were analysed first in it snatural root in a left heart simulator using glycerol at 120/80 mm Hg pressure and 4 l min^-1 Cardiac Output (C.O.). Then the valve was implanted in the porcine root and studied: Group I (n = 4) 1-2 mm smaller, Group II (n = 8) 3-4 mm smaller and Group III (n = 4) 5-7 mm smaller donor valve than the recipient. A silicone rubber mould of the implanted valve was made and analysed. In the donor aortic root the commissural expansion for 0 to 80 mm Hg pressure was 42% which was reduced significantly in all assemblies. Group I showed the largest decrease in the orifice area (OA). In Group III decrease in the OA was less, however, two of the four valves had aortic insufficiency (AI). In Group II decrease in the OA was only 13% and there was no AI. During opening the leaflet surface was smooth and freeof wrinkles in the intact valve, but had creases and folds in all three groups. All implanted valves had an indentation along the suture line disrupting the leaflet-sinus continuity. Hence, to enhance valve longevity, donor valve 3-4 mm smaller than the recipient should be chosen and the implantation technique modified to preserve the leaflet-sinus continuity.