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Forty patients who came to necropsy over a period of five years due to myocardial damage sustained during cardiac valve replacements were studied. The clinical presentation of myocardial damage was assessed in relation to the preoperative cardiac status. The cause and nature of myocardial damage were assessed at necropsy. Evidence of clinical, electrocardiographic and aortographic coronary atheroma was correlated with distribution at necropsy, and the value of selective coronary angiography in perfusing the coronary arteries during cardiopulmonary bypass is stressed. The causes of myocardial damage could be classified as (a) thrombo-embolic, (b) iatrogenic damage to the coronary arteries, and (c) poor or absent coronary perfusion during cardiopulmonary bypass. A case is made for the importance of coronary perfusion during cardiopulmonary bypass.With better understanding of the nutrient requirements of the myocardium, deaths due to myocardial damage sustained during cardiopulmonary bypass are now fortunately infrequent. However, over a period of five years (1965 to 1969) 40 such patients came to necropsy at Sully Hospital, an incidence of about 5% in a yearly output of about 120 valve replacements. The aim of this paper is to study the pathophysiology of myocardial damage in these patients with reference to the incidence of coronary artery disease and to assess the factors adverse to the myocardium during and after cardiopulmonary bypass. In particular, the role of coronary perfusion is outlined, because its use is debatable, and because oxygen requirements and the coronary blood flow demands of the myocardium with non-pulsatile flow and hypothermic perfusate in the beating and fibrillating heart are only now being gradually understood (Sterns, Bonnabeau, and Lillehei, 1966;Vasko, 1967). When coronary atheroma predominates and results in areas of perfusion deficit in the myocardium, the role of coronary perfusion during cardiopulmonary bypass assumes all the more importance. It is in respect of this role that we have looked critically at our coronary perfusion techniques and related them to the myocardial damage sustained in this group of patients.

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