A computer interprets the patient’s ECG and provides timing signals that control the sequential inflation and deflation of pressure cuffs wrapped around the patient’s calves, thighs and buttocks. Each inflation cycle is timed to start and end during the resting phase of the patient’s heartbeat (diastole).

As diastole begins, the cuffs inflate rapidly and sequentially from the calves to the buttocks, firmly compressing the patient’s vasculature. This has two immediate effects: One, a strong retrograde “counterpulse” occurs in the arterial system, forcing fresh oxygenated blood back toward the heart and coronary arteries, and two, an increased volume of venous blood is returned to the heart under increased pressure. The combined effect of these two events is to increase the oxygen supply and perfusion pressure in the myocardium (heart muscle) and to increase “pre-load” so the heart has a greater volume of blood to pump during the next systolic event. Next, as the patient’s heart nears the end of diastole and prepares for systole (ventricular contraction), the computer instructs the deflation valves to open so a vacuum can deflate the cuffs instantly.

This action also provides therapeutic advantages by reducing the heart’s after-load. Since the vascular beds in the lower extremities are essentially empty, the resistance to blood flow is markedly reduced, thereby decreasing the amount of work that the heart must do to pump blood to these areas (reducing oxygen demand within the myocardium). As a result of these diastolic augmentation activities, the patient’s peak diastolic pressure is significantly increased, benefiting circulation in the heart muscle and in other organs as well. At the same time, the patient’s systolic pressure is reduced, to the general benefit of the vascular system.

Clinical studies suggest that the increase in myocardial perfusion pressure stimulates the use of collateral vessels that are already present, but unused, thereby allowing oxygenated blood to bypass ischemic (starved) areas in the heart. Other cardiologists believe that the myocardium may actually develop new vasculature of tiny blood vessels that facilitate blood flow to the heart muscle.