EFFECT OF WARM ISCHEMIA AND CRYOPRESERVATION ON CELL VIABILITY OF HUMAN ALLOGRAFT VALVES

Fibroblast viability of the allograft valve leaflet has been suggested to affect clinical durability. Warm ischemic time is thought to be on e of the critical determinants of cell viability. We assessed cell via bility of allograft valves by now cytometry, using a fluorescein diace tate-propidium iodide stain to characterize the effects of warm ischem ia and cryopreservation on viability. Twelve human pulmonary valves wi th harvest-related warm ischemic times (range, 70 to 520 minutes; mean +/- standard deviation, 225 +/- 157 minutes) were studied by now cyto metry. We assessed cell Viability of the allograft valve leaflets befo re and 30 days after storage. A significant negative correlation was f ound between warm ischemic time (x minutes) and cell viability (y%) be fore (y = -0.024x + 96.7; r(2) = 0.62; p = 0.002) and after 30 days of storage (y = -0.036x + 94.0; r(2) = 0.86; p = 0.001). Cell viability of the cryopreserved allograft valves was well preserved (>70%) with a warm ischemic time less than 520 minutes (8.7 hours).