Enhanced External Counterpulsation in Unrevascularizable Patients.

Enhanced external counterpulsation (EECP) is a noninvasive outpatient therapy for the treatment of chronic angina. EECP treatment produces an acute hemodynamic effect that is similar to that produced by the invasive intra-aortic balloon pump. Three sets of cuffs on the upper thigh, lower thigh, and calves of each leg are inflated with compressed air during the diastolic phase of the cardiac cycle and are deflated in early systole. This rapid inflation and deflation raises diastolic aortic pressure, increases coronary perfusion pressure, and provides improved afterload reduction and increased venous return with a subsequent increase in cardiac output. Enhanced external counterpulsation has been shown to provide long-term symptom relief in patients with ischemic heart disease in several case series, as well as in a randomized trial. Up to 80% of patients selected for treatment have a positive clinical response, and an associated objective improvement has been demonstrated by functional imaging in several case series. A treatment course consists of 35 1-hour sessions over a 7-week period and is generally well tolerated with a low risk of adverse events. Development and enhancement of collateral channels, as well as peripheral conditioning and neurohumoral effects, may play a role in providing symptomatic relief. Studies are ongoing to determine the mechanism of action and to further define subsets of patients who might benefit.