Figure 52-5 Determinants of myocardial oxygen supply and demand that lead to myocardial ischemia. During the perioperative period, virtually every determinant is altered by factors such as fluid shifts, blood loss, pain, catecholamines, altered coagulability, and ventilatory insufficiency. (Adapted from Beattie C, Fleisher LA: Perioperative myocardial ischemia and infarction. In Beattie C, Fleisher LA [eds]: International Anesthesiology Clinics. Boston, Little, Brown, 1992, pp 12–24.)