William C. Birtwell

Assisted Circulation II. Effects of Counterpulsation on Left Ventricular Oxygen Consumption and Hemodynamics

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 qO2, 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 qO2, despite a fall in tension-time index. The influence of counterpulsation upon the energy requirements of the left ventricle is briefly discussed.

Synchronous pressure assist-counterpulsation

Abstract Experimental evidence indicates that counterpulsation should be an effective approach to the treatment of cardiogenic shock. Left ventricular work is reduced, diastolic pressure is increased and coronary flow is augmented. There is also evidence that the increased diastolic pressure may accelerate and magnify the development of collateral circulation in the myocardium thus providing an extended benefit to the heart. External pressure assist provides the effects of counterpulsation in a manner which is atraumatic and well adapted to the clinical environment. This modality also provides control over blood volume distribution and venous return which should increase the versatility of the procedure.