Comparison of structural valve failure among different 'models' of homograft valves.

Aortic homograft valves are accepted as excellent valve substitutes in the aortic position. Compared to stented bioprostheses, they are considered to have better hemodynamics and a zero or negligible thrombogenicity. Their perceived major single shortcoming is limited durability, but there is apparent broad variation within published data in this respect. Study of the relevant literature reveals important differences between procurement, sterilization and preservation of the individual series refuting any attempt at making a scientifically valid comparison of overall performances. Surgical method and patient selection are further sources of variation among reported long term results. Nevertheless, it appears that (a) cryopreservation produces results at least as good as those of other preservation methods, and (b) the worst results are those of series with the longest follow up. However, the good results with cryopreserved valves are reported in series with limited length of follow up. Because of the many variable factors associated with the use of homograft valves, a comprehensive set of definitions should be introduced, accepted and adhered to in reporting results.