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

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 s natural root in a left heart simulator using glycerol at 120/80 mm Hg pre ssure and 4 l min(-1) Cardiac Output (C.O.). Then the valve was implanted i n 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. Gro up I showed the largest decrease in the orifice area (OA). In Group III dec rease in the OA was less, however, two of the four valves had aortic insuff iciency (AI). In Group II decrease in the OA was only 13% and there was no AI. During opening the leaflet surface was smooth and free of wrinkles in t he intact valve, but had creases and folds in all three groups. All implant ed valves had an indentation along the suture line disrupting the leaflet- sinus continuity. Hence, to enhance valve longevity, donor valve 3-4 mm sma ller than the recipient should be chosen and the implantation technique mod ified to preserve the leaflet-sinus continuity.