Eff ect of enhanced external counterpulsation depends on arterial compliance

Abstract

Enhanced external counterpulsation (EECP) is a non-invasive therapy off ered to patients with refractory angina pectoris. Previous studies have demonstrated that its clinical eff ect depends on the diastolic/systolic augmentation ratio (D/S ratio). We hypothesized that the D/S ratio is associated with arterial stiff ness measured as pulse wave velocity (PWV) and brachial pulse pressure (PP). Twenty patients with known refractory angina (17 men, 3 women; mean age 64 years) were included and underwent one hour of EECP treatment (Vasomedical Inc., Westbury, NY, USA). Three sets of cuff s were applied around the lower extremities. Gated by electrocardiography (ECG), air was infl ated in diastole at a pressure of 260 mmHg and defl ated at the start of systole. The D/S ratio was monitored with fi nger plethysmography. Carotid-femoral pulse wave velocity (PWV) was measured with mechanotransducers (Complior SP, Artech Medical, France). PWV and brachial BP were measured at baseline before EECP.The mean (SD) BP was 140 (23.5)/77 (9.9) mmHg, PP 62.8 (18.3) mmHg and PWV 10.8 (4.4) m/s. EECP treatment increased the D/S ratio during a one-hour session compared with baseline (1.30 (0.11) vs. 0.56 (0.04) P< 0.001), and the D/S ratio at 45 min. was signifi cantly correlated with PWV (r = 0.49, P< 0.05) and PP (r = 0.58, P< 0.05).We demonstrated that the diastolic augmentation (D/S ratio) during EECP treatment depends on arterial stiff ness. The results suggest that arterial compliance has a crucial infl uence on the eff ect of EECP and that large-artery stiff ness may reduce the eff ect of EECP.