Long term performance of 580 homograft and autograft valves used for aortic valve replacement

Homograft valves have been used at the National Heart Hospital since 1964, and autograft valves since 1967. The homografts were treated either by freeze drying, by flash freezing, or by tissue maintenance in a nutrient medium (fresh). In order to compare these three groups of homograft valves with the autograft valves some long term assessment of valve function was required. In the whole group of 580 valves there have been 40 late deaths, which is a probability of only 7% over 6 to 14 years. Homografts and autografts are therefore excellent valves in terms of patient survival. Thromboembolism, haemolysis and bleeding may be regarded as complications which do not occur with homograft and autograft valves. There was one thrombogenic episode in this group, an incidence of one per 11,994 patient years and a probability of only 0.000083 patient years. Potentially fatal hazards of late complications with homoor autograft valves decrease with time and at this time is a negligible factor. The similarity in pattern of onset of late infections and degeneration probably reflects the greater susceptibility to infection of a degenerating valve. All three groups of homografts are very similar and differ only from the excellent performance of the autograft valves.