Intra-aortic balloon versus extra-aortic counterpulsation in severe cardiac failure differences in aortic input impedance and left ventricular power generation

In order to evaluate the efficacy of counterpulsation for different cardiac assist device configurations, a valveless single orifice polyurethane ventricle was implanted on the brachlocephalic artery in sheep(n=14) to provide extra-aortic counterpulsation. In parallel, an intra-aortic balloon was placed in the descending aorta. Both devices were pneumatically driven with a standard intra-aortic balloon pump console at a preload of 40°c. Severe cardiac failure was induced with high dosages of esmolol. Measured parameters were aortic pressure and flow, and left ventricular pressure. Tension-time index, total aortic flow, end diastolic pressure, aortic input impedance, and left ventricular power output were computed. Results indicate that the fundamental components of aortic input impedance and left ventricular power output are reliable predictors of the efficacy of counterpulsation for the experimental model used in this study.