Hypothermic preservation of the canine heart

In the assessment of any cardiac preservation system, the only acceptable criterion of organ viability is orthotopic transplantation with survival of the animal for at least 72 hr with no respiratory or vasopressor support required beyond that time. Severe but reversible damage incurred during storage is acceptable in organs such as the kidney, but the obligatory need for immediate adequate function allows no such leeway with heart grafts. Several points are apparent from the experiments with saline preserved hearts. First, at 37°C the maximum ischemic interval is short, and intervals longer than 30 min invariably render the organ nonviable. The inverse relation between the logarithm of the temperature and the maximal ischemic interval is consistent with the similar relation between metabolic rate and temperature. The inability to obtain routine survival after storage below 15°C was an unexpected finding. Although an occasional animal survived after having the heart graft stored in saline at 4°C, and although previous reports have demonstrated survival after 7 hr of saline hypothermic preservation, consistent survival was not obtained.