The Effect of Intraaortic Balloon Counterpulsation

required for relief of myocardial ischemia. IABP decreased the rate7pressure product and aortic enddiastoliczpressure, and the peak systolic aortic pressure and regional myocardial oxygen consumption declined inall but one patient. Peak and mean aortic diastolic pressures increased. Changes in regional coronary blood flow paralleled changes in peak systolic aortic pressure (r = 0.92, p < 0.007). Thus, relief of angina during IABP could not be ascribed to an increase in regional coronary blood flow. Reduction of myocardial oxygen consumption is the most likely mechanism by which IABP relieves myocardial ischemia in patients with unstable angina pectoris.