Cytochrome C used at the postischemic period causes a rapid reestablishment of coronary circulation, hemodynamic parameters, prevents activation of lipid peroxidation in reoxygenation of the heart after prolonged total myocardial ischemia in patients with acute bacterial endocarditis in whom the prostheses of heart valves had been fulfilled. Parallel with the positive inotropic effect, Cytochrome C reduces the postloading and, as a result, transfers the cardiac muscle to a more profitable regimen. At the end of the myocardial ischemia period Cytochrome C provides rapid and effective recovery of the bioelectrical function of the heart, improves its pumping function, thus allowing the dose and duration of inotropic stimulation of the myocardium at the postischemic period to be reduced, lowers pulmonary resistance and finally leads to less postoperative intrahospital lethality from acute heart failure.