MAXIMIZING THE HEMODYNAMIC BENEFIT OF ENHANCED EXTERNAL COUNTERPULSATION

Background: Enhanced external counterpulsation (EECP) has been demonst rated to be an effective treatment for angina and exertional ischemia in patients with coronary disease. Hypothesis: It is hypothesized that the ability of EECP to enhance the recruitment or development of coro nary collaterals in coronary artery disease may be determined by the r elative magnitude of diastolic augmentation (DA) and systolic unloadin g (SU). This study examines the relation between the proposed EECP eff ectiveness ratio (DA/SU), as assessed by finger plethysmography, and c hanges in descending aortic flow as assessed by Doppler echocardiograp hy in 15 patients during EECP. Methods: Varying external cuff pressure s (0-275 mmHg) were used to generate a range of DA/SU ratios. The effe ct on aortic antegrade systolic and retrograde diastolic flow was asse ssed by Doppler echocardiography to determine whether there was an opt imal EECP effectiveness ratio that maximizes the hemodynamic effects o f EECP. With increasing DA/SU there was an initial positive linear inc rease in both systolic and diastolic flow volume. Systolic flow maximi zed at an effectiveness ratio of 1.5 and diastolic flow at a ratio of 2.0, Result: Therefore, effectiveness ratios (DA/SU) in the range of 1 .5-2.0 are optimal for maximizing the hemodynamic effects of EECP.