Abstract
The limits of myocardial tolerance of the preserved canine heart at various conditions were studied by the heart transplantation method.
1. Without heparinization of the heart, the time limit may be 2 to 3 hours at 19°C.
2. Preventing blood coagulation by heavy heparinization, preserved hearts may be shut out of circulation up to 30 hours and resume a normal cardiac rhythm.
3. Perfusion of the coronary vessels to wash out all blood extends the limits as does complete heparinization.
4. The time limits of viability of preserved heart are related not solely to the length of acute ischemia but more to the patency of capillary bed. Hypothermic preservation is another very effective method to extend the limits, whereas the kind of preserving solutions showed no conclusive difference in the present experiments.
