Viability of fresh mitral homograft valves

The present study was undertaken to measure and compare the viability of the mitral leaflet, chordae, and papillary muscle. The viability of the valves was assessed by autoradiography at regular intervals after sterilization and preservation in antibiotics and nutrient medium. The results showed different rates of decline in viability of the leaflet, muscle, and chordae of the mitral valves. Slightly more than 70 % of the leaflet fibroblasts took up thymidine during the first 24 hours of storage. This is compared with 68 % of papillary muscle fibroblasts and 40% of chordae fibroblasts. Viability of the chordae decreased rapidly and became pronounced at four weeks. One week is the maximum time for storage of mitral valves if it is desirable to preserve living cells in the chordae. Cadaveric mitral homograft valves had been used (by D.N.R.) as a replacement of the mitral valve. Although the structural integrity of the leaflet and the papillary muscle did not deteriorate after several months of implantation in patients, the chordae were liable to deteriorate and rupture. This may be related in some measure to the fact that the chordae lack living cells. As it has become clear that the long-term function of aortic homograft valves relates to the methods of sterilization and storage used (Hudson, 1966; Smith, 1967; Davies et al., 1968) storage in antibiotic and nutrient media could be advantageous for the mitral valves also. This paper records an attempt to measure and compare the viability of the mitral leaflet, chordae, and papillary muscle using an autoradiographic technique already described (Al-Janabi, Gonzalez