The coronary collaterals: their development, morphology, function, and classification.

Coronary collaterals are important in evaluations made for bypass coronary artery surgery because of their role in the preservation of myocardial function. This paper attempts to define collaterals, explain how they develop, and describe what role they play in the normal heart. It presents a model of the different types of coronary collaterals, emphasizing the intracoronary and intercoronary anastomoses. The controversial role of the function of collaterals in coronary artery disease is discussed extensively, with special attention given to more recent angiographic in vivo studies. Recent investigations indicate that collaterals may limit the size of myocardial infarction as they help to preserve myocardial functions; they assist in the evaluation of both runoff and function for patients being considered for bypass surgery. As more is learned about collaterals, undoubtedly we shall gain a greater appreciation of their significance.