The Role of Emergency Bypass Surgery in Acute Myocardial Infarction

Abstract

A number of interventions have been proposed to reduce myocardial damage following acute myocardial infarction, primarily by improving the balance between myocardial oxygen supply and demand. Experimental studies have demonstrated that increasing the oxygen supply by reperfusion can result in the salvage of substantial myocardium and that this is more effective than pharmacologic techniques aimed at reducing oxygen demands. Despite a large experience in animals that has defined the time limits for successful reperfusion, the precise limits in humans have not been determined. While reperfusion in animals following acute occlusion of a coronary artery must be carried out within 1–2 hours to salvage substantial myocardium, the presence of collateral circulation to areas of myocardium at risk in humans, as well as the occurrence of subtotal occlusions, may permit successful reperfusion for up to 6–8 hours, or even longer, after the onset of symptoms of acute myocardial infarction. For this reason, emergency coronary artery bypass grafting has been evaluated as a method to establish immediate reperfusion to the ischemic zone. It provides the additional theoretical advantage of permitting simultaneous revascularization of areas of jeopardized myocardium remote from the area of infarction. In this chapter, the role of emergency surgical revascularization in several clinical settings of acute myocardial infarction is reviewed.