Evaluation of myocardial metabolism after prolonged circulatory arrest and under profound hypothermia. An experimental study in young dogs.

15 young dogs between the ages of 2 and 4 months and weighing less than 6 kg underwent circulatory arrest for 1 h combined with profound hypothermia and extracorporeal circulation. During reperfusion, myocardial metabolism was studied by comparing the oxygen arteriovenous content difference and lactate balance at different temperatures. As the myocardial temperatures rose, the oxygen arterial venous difference increased from 4 vol/100 ml at 25 degrees C to 10 vol/100 ml; lactate balance changed from -19.3 to +8% which because of a large rise in arterial lactate indicates a considerable increase in lactate consumption. This study shows that profound and generalized hypothermia ensures good myocardial protection during at least 1 h of ishcemia and confirms results obtained with other forms of cardiac hypothermia.