Current nonpharmacologic management of coronary artery disease: Focus on external counterpulsation

Abstract

The basic principle of enhanced external counterpulsation (EECP) is diastolic augmentation of arterial pressure, lowering of systolic arterial pressure along with increasing venous return. EECP is a noninvasive procedure involving sequential inflation and rapid deflation of compressive cuffs wrapped around the patient's calves, thighs, and lower abdomen, timed to the cardiac cycle using the electrocardiogram. Theoretically, this should result in decreased myocardial oxygen demand and an increased coronary blood flow. Long-term benefits may be the result of the opening of dormant coronary collateral circulation, but this is theory and not proven. Extracardiac factors, such as peripheral arterial stiffness, endothelial dysfunction, and elevated myocardial oxygen demand, are also the therapeutic targets for EECP. There is some evidence that long-term benefits may be the result of a training effect due to 35 1-hour diastolic inflations at 300 mm Hg and systolic deflations of the compressive cuffs. To date, the extracardiac effects of EECP have received little attention and peripheral vascular adaptations to EECP have not been investigated. EECP, by promoting lower-extremity arterial "run-off" and intermittent reactive hyperemia in the legs with each inflation/deflation cycle of the compressive cuffs, may improve peripheral vascular function, thus inducing changes in peripheral vascular biology that will reduce ventricular work and myocardial oxygen demand in patients with coronary artery disease similar to that of exercise. At the University of Florida, this therapy is used for patients with chronic stable angina who are refractory to medical therapy and are not candidates for a revascularization procedure. The treatment does take time (35 once-a-day 1-hour treatments), and not all patients are candidates for the procedure. For example, patients with severe peripheral vascular disease, severe hypertension, thrombophlebitis, markedly irregular heart rhythm, and severe aorta insufficiency are excluded. Approximately 75% of patients report improvement (ie, a decrease in symptoms and an increase in exercise duration). Our results are such that this management strategy does deserve consideration in patients with persistent chronic stable angina on maximum medical therapy who are not candidates for revascularization and are unhappy with their lifestyle.