Valve graft sterility is a prerequisite for long term success in transplantation of homologous or heterologous aortic valves. Grafts obtained sterilely or unsterilely have been treated with β-propiolactone,1,2 ethylene oxide,3 irradiation,4,5 4% buffered formaldehyde solution (formalin),6 and antibiotic solutions.7 These methods are generally considered effective in eliminating organisms from the tissue. However, the long-term resistance to infection of grafts so prepared is not known. Endocarditis involving the homograft has been reported by several investigators utilizing these techniques,4,6,8-11 although the incidence is not particularly higher than prosthetic substitutes. Analysis of our own experience12 with the β-propiolactone sterilized valve revealed late failure from infection in a high percentage of cases, but common bacteria were not responsible for failure in most patients.
The relative importance of factors such as the type of bacteria present at the time of harvest, interval between donor's death and valve procurement,