Benefits and pitfalls of warm blood cardioplegia in heart valve replacement: systemic protective effects

The purpose of this paper was to assess the role of continuous warm blood cardioplegia in heart valve replacement in comparison with standard intermittent cold crystalloid cardioplegia. Twenty patients undergoing open heart valve replacement were divided arbitrarily into two groups in this study; Group I was given intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) (10 patients) and Group II was given continuous administration of warm blood cardioplegia with normothermic CPB (10 patients). The groups were similar with respect to sex, age, body surface area and preoperative ventricular function. Bypass conditions as well as perioperative complications were evaluated in the respective groups. Peak values of the serum enzyme levels within 120 hours of postoperation including alanine transaminase, aspartate aminotransferase, lactate dehydrogenase (LDH) and its isoenzymes LDH1 + LDH2, phosphokinase (CK) and its isoenzyme CK-MB, superoxide dismutase, and malondialdehyde in the two groups were also assessed. Biopsies from the right atrium were obtained immediately before aortic cross clamp removal (ischemic period), and 30 minutes after cross clamp removal (reperfusion period). Myocardial structures were observed and scored. No significant intergroup differences were found in the bypass conditions except for the perfusion flow, systemic temperature and central venous pressure. There were no significant differences in the intergroup perioperative complications, either. Serum enzymes except CK which reached peak values in Group I appeared prior to or consistent with Group II. There were no significant intergroup differences in peak levels of the serum enzymes except CK (307.44 +/- 38.56 U/L vs. 466.29 +/- 52.03 U/L, p = 0.039 for CK). From the pathological assessment, the structural alterations were the most severe during the reperfusion period in group I. Myocardial damage showed more severely in reperfusion than in ischemia in both. Warm blood cardioplegic technique, raising potential hazards, is still a practical method for myocardial protection in open heart surgery, but might be less effective in protecting the tissues beyond myocardium.