FIELD: medicine. SUBSTANCE: method involves cutting off pieces of myocardium as bioptates and preparing ultrathin slices that are contrasted and studied using electron microscope. Perfusion degree of myocardial capillary bed is determined from the number of open and closed capillaries. Mechanisms controlling capillaries isolation from blood circulation are differentially determined in a group of closed capillaries. Proportion of capillaries closed due to pathologic mechanisms acting, compared to the total number of idle capillaries allows to evaluate myocardial capillaries performance in various pathophysiological states. EFFECT: enhanced accuracy in predicting postoperative period recovery course; high level of myocardium protection against ischemia and reperfusion injuries. 1 tbl
