Background: The injury resulting from postmortem ischemia is a critical deterrent to the availability of donor valves. Using the reduction of XTT-tetrazolium salt as a marker of metabolic sequelae, we assessed the injurious effect of ischemia and the metabolic sequelae in 156 porcine semilunar leaflets.
Methods: The leaflets were randomly allocated to noncryoprocessed (n = 72) or cryoprocessed (n = 72) groups. At each preservation temperature of 4 degrees C, 24 degrees C, or 37 degrees C, 24 leaflets each were exposed to one of four storage periods of 9, 17, 30, or 60 hours. Twelve fresh aortic leaflets served as baseline reference samples.
Results: There was a progressive loss in the metabolic functioning of valve leaflet cells in both noncryopreserved and cryopreserved tissue as the storage times increased. Cryopreserved tissue showed a greater loss of function than noncryopreserved tissue did. The metabolic injury was mainly a consequence of cryoprocessing. The greatest loss in metabolic functioning occurred in the valves stored for 60 hours. The least favorable combination of variables was cryopreservation and a precryopreservation storage time of 60 hours.
Conclusions: We conclude that 30- to 60-hour delays do not have a significant metabolic effect on cardiac leaflets. Thus it may be possible to safely extend the permissible ischemic periods after organ harvest.