Cardioplegia in the presence or absence of calcium.
The effect of the Bretschneider procedure of myocardial protection on the recovery of dog hearts in the postischemic phase after 90 min of aortic occlusion was studied. In one series of experiments, Bretschneider's calcium-free cardioplegic solution HTP was used; in a second series, 5 X 10(-5) M CaCl2 was added to this solution. The coronary system was perfused with cardioplegic solution (6 degrees C) for 6 min at the onset and for 1 min after 30 and 60 min of ischemic arrest. Functional recovery of the heart and plasma creatine kinase activity during the postischemic phase were not significantly different in the two groups of dogs. It is concluded that low temperature, mode of administration, and composition of Bretschneider's cardioplegic solution HTP protect the heart against the potential danger of exposure to a calcium-free solution.