A device used to reduce left ventricular systolic work, left ventricular end-diastolic pressure, and wall tension. It is inserted into the descending aorta via the femoral artery either percutaneously or by surgical cut-down. The balloon rapidly deflates just before ventricular systole to reduce the impedance to left ventricular ejection. It then rapidly inflates immediately following aortic valve closure to augment diastolic coronary perfusion pressure.