Assisted Circulation

Abstract

The effect of counterpulsation upon hemodynamics and myocardial oxygen consumption was studied in 14 dogs. With properly synchronized counterpulsation, a reduction in mean systolic pressure, tension-time index, left ventricular work, and myocardial oxygen consumption was observed, with no change in effective cardiac output. The reduction in myocardial qO ₂ , however, did not parallel the fall in tension-time index. Mechanical efficiency fell and the oxygen cost of pressure generation by the left ventricle rose. Premature triggering of the pump systole resulted in an actual increase in myocardial qO ₂ , despite a fall in tension-time index. The influence of counterpulsation upon the energy requirements of the left ventricle is briefly discussed.