Preservation of myocardial ultrastructure.

This study compares the effects of 2 hour periods of normothermic anoxic arrest, continuous normothermic coronary perfusion, continuous cold coronary perfusion, and topical cooling of the ischemic myocardium on survival and ultramicroscopic structure of the canine myocardium. No animal survived 2 hours of normothermic anoxic arrest. Severe ultrastructural damage was observed in the nuclei, mitochondria, and myofibrils. Topical cooling of the ischemic myocardium to 15 degrees C. markedly improved survival and preservation of the myocardial fine structure. Continuous perfusion of the coronary arteries with cold blood resulted in 100 per cent survival through the experimental period, with preservation of the normal myocardial ultrastructure. The technique of cold coronary perfusion should be particularly useful in cardiac surgical patients in whom maximal preservation of myocardial function is essential for survival.