BACKGROUND: Recent interest in the use of normothermic blood cardioplegia is based on theoretical advantages over the traditional method of hypothermic myocardial protection. These reported advantages are a decrease in intraaortic balloon pump use, greater incidence of return to normal sinus rhythm, greater immediate cardiac outputs, and less time weaned from bypass after removal of the aortic cross-clamp. In addition to these advantages, normothermic blood cardioplegia offers the promise to resuscitate the ischemic myocardium and reduce the morbidity and mortality for patients with high-risk disease. This study was designed to compare the effects of cold crystalloid and normothermic blood cardioplegia on the postoperative recovery. METHODS: To evaluate the efficacy of cold versus normothermic cardioplegia, forty-four patients scheduled to undergoing valvular replacement surgery were selected to receive intermittent cold(4degrees C) crystalloid cardioplegia(n=22), group I or continuous normothermic(37degrees C) blood cardioplegia(n=22), group II. Cardiopulmonary bypass(CPB) and aortic cross-clamp(ACC) times were measured during the operation and patients were evaluated postoperatively for serum electrolytes, arterial blood gas analysis, blood pressure, heart rate, complications, ventilator periods and ICU stay. RESULTS: The ACC and CPB times were significantly longer in group II(165.9+/-44.8 min, 210.9+/-60.2 min) compared with group I(121.2+/-38.7 min, 149.7+/-38.1 min)(p<0.01). Group II patients had significantly higher serum potassium level(5.2+/-0.8 mEq/L) than group I(4.3+/-0.4 mEq/L) on the first postoperative day(p<0.01). ICU stay and ventilator period were not significantly different in two groups. There was no significant difference in postoperative complications and mortality rates between two groups. CONCLUSIONS: These results suggest that the continuous normothermic blood cardioplegia may be useful in myocardial protection during cardiac operation.