A symposium on surgery for coronary artery disease. Pre-infarction syndrome--surgical indications

Although the atherosclerotic process does not penetrate the coronary circulation at subendocardial levesl, the hemodynamic effects of coronary arterial narrowing occur at the endocardial and myocardial cellular levels. Theee resultant deprivation of blood supply to these tissue areas eventually leads to myocardial infarction. In certain clinical situations, a sudden increase in symptoms signifies and impending acute ischemic process. Three parameters have clinically been used to evaluate the changes that lead progressively to myocardial infarction: symptoms, electrocardiogram, and serum enzyme levels. The typical preinfarction patient experiences episodes of acute angina pectoris, sometimes intense and prolonged, and often unresponsive to nitroglycerin. Physical examination is usually not remarkable, serum enzyme levels are normal if tissue damage has not occurred, and the electrocardiogram is variable with pain. Th pathologic process in the preinfarction patient is frequently confined to the proximal arterial segment of one or more of the coronary arteries, usually in the form of a high-grade (in excess of 95 per cent) atherosclerotic lesion. This pathologic condition presents a satisfactory distal arterial segment suitable for bypass, and these patients are ideal candidates for urgent myocardial revascularization.