Numerical simulation of enhanced external counterpulsation

Enhanced external counterpulsation (EECP) is a noninvasive, counterpulsativ e method to provide temporary aid to the failing heart by sequentially infl ating cuffs on the lon:er extremity out-of-phase with the left ventricle. O ptimization of the method necessitates consideration of the hemodynamics co ated by EECP and the mode of action providing patient benefit. A computatio nal model based on the governing one-dimensional equations is developed tha t simulates cardiovascular hemodynamics during EECP. The model includes a 3 0-element arterial system including the left ventricle, bifurcations. and p eripheral arterial vessels. Effects of vessel collapse as external pressure is applied, arterial refilling on pressure release, changes in aortic pres sure, and shear stress generated in the arteries are each investigated. Dev ice parameters are systematically varied to determine their effect on syste m performance. Results show the potential for significant collapse and shea r augmentation throughout the arteries of the lower extremity Performance i s strongly influenced by the mean level of external pressurization and the timing of cliff inflation, but less so by the relative timing and pressure differences between cuff segments. (C) 2001 Biomedical Engineering Society.