INTERRUPTED WARM BLOOD CARDIOPLEGIA FOR CORONARY-ARTERY BYPASS-GRAFTING

Continuous warm blood cardioplegia has been used with good clinical outcome in both antegrade and retrograde delivery. However, the continuous delivery of cardioplegia is sometimes interrupted for adequate visualization and flow is not constant with heart manipulation during operation. We studied the effects of interrupted antegrade delivery of warm blood cardioplegia on myocardial metabolism and clinical results after surgery. Fifty-five patients undergoing isolated coronary bypass surgery received warm blood cardioplegia (n=29) or cold crystalloid cardioplegia (n=26) in an antegrade fashion. During reperfusion, myocardial oxygen consumption, lactate extraction, creatinine kinase isoenzyme (CK-MB), and malondialdehyde (MDA) were measured. Postoperatively, serum CK-MB and cardiac output (GO) were determined over a period of time. Myocardial oxygen extraction in the warm group was significantly greater than in the cold group 1 min after reperfusion (P<0.02). The results revealed a tendency for patients in the warm group to have prior lactate extraction, although the difference did not reach statistic difference (P<0.10). After removal of the aortic cross-clamp, the heart returned to sinus rhythm spontaneously in 90% of the patients with warm cardioplegia and 15.4% of those with a cold heart (P<0.01). Postoperatively, there was no significant CK-MB or MDA release in either group except for one patient with perioperative myocardial infarction. After operation inotropic support was required for two and one patient in the warm and cold groups, respectively, although there were significantly more patients with poor left ventricular function in the warm, than in the cold, group (P<0.05). The improvement ratio in cardiac output (postoperative CO/preoperative CO) in the warm group was 1.24 and 1.09 with the cold cardioplegia and clinical outcome was essentially the same. Conclusively, the present results show that interrupted warm blood cardioplegia gives a good operative field with safe, effective myocardial protection during operation and good clinical outcome.