Preservation of the isolated canine heart in 4 degrees C air with intermittent infusion of a cardioplegic solution

The objective of this study is to determine whether intermittent infusions of cardioplegic solution has any effect on the isolated heart immersed in 4 degrees C saline. Further, in an attempt to prevent myocardial edema from developing during prolonged preservation, we stored the heart suspended in 4 degrees C air. In Experiment 1, 24 canine hearts were isolated after cardiac arrest induced by the infusion of 4 degrees C St. Thomas' Hospital Solution (STS). The isolated hearts were immediately immersed in 4 degrees C saline and divided into three groups (n = 8 in each group). The hearts were stored for 9 hours in 4 degrees C saline in Group 1 as well as in Group 2, however in the latter group intermittent infusions of STS were also given every 2 hours. In group 3, the hearts were suspended in 4 degrees C humidified air with intermittent infusions of STS every 2 hours. Intramyocardial pH showed a progressive fall in all 3 groups without significant difference in the rate of decrease among the groups (0.14/h in Group 1, 0.16/h in Group 2 and 0.13/h in Group 3, p less than 0.18). The ATP levels at 1 hour after excision were nearly the same in the three groups (about 25.9-26.3 micrograms/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)