The effects of global ischemia and reperfusion on human myocardium: quantitative evaluation by electron microscopic morphometry.

During open-heart operation, myocardial biopsies were taken from 31 patients undergoing aortic valve replacement during total cardiopulmonary bypass. The first needle biopsy was taken before induction of cardiac arrest (Kirsch cardioplegia), the second at the end of global ischemia, and the third during the reperfusion period. Teh tissue was investigated by electron microscopy, in both a qualitative and a quantitative manner (morphometry). Ultrastructural morphometry revealed cellular and especially mitochondrial swelling that occurred during the reperfusion phase, but not after ischemia alone. On the basis of morphological measurements, this study shows the occurrence of postischemic cellular and mitochondrial edema that possibly might be avoided by the use of improved techniques of myocardial protection during operation.