Coronary Artery Reperfusion: Early Effects on Coronary Hemodynamics

Abstract

Since cardiac failure in acute myocardial infarction most likely results from a large myocardial infarct (1, 2), several experimental approaches to effectively decrease the size of the developing infarct (3–9) have been made. In general, these approaches either decrease myocardial oxygen demand relative to supply or enhance anaerobic metabolism. A more direct approach would increase oxygen supply by restoring blood flow beyond the site of obstruction, i.e., coronary artery reperfusion. When coronary reperfusion was established within 3 hours of occlusion, significant myocardial tissue was salvaged and impaired left ventricular function was reversed (10, 11). These studies assume that since the coronary vascular bed is usually anatomically patent beyond the site of obstruction (12, 13) the coronary vascular bed has maintained the same capability to carry flow at all times. But evidence from other vascular beds shows that when occlusion is of sufficient duration, functional changes may occur which can impair the ability of the vascular bed to maintain flow when reperfusion is instituted (14). Accordingly, we sought to determine whether the duration of ischemia can alter the functional capacity of the coronary vascular bed at the time of reperfusion.