External counterpulsation (ECP) is a procedure performed on individuals with ischemic cardiomyopathy
in order to diminish the symptoms of their ischemia
. In various studies, ECP has been shown to relieve angina
, improve exercise tolerance, and decrease the degree of ischemia in a cardiac stress test
.While an individual is undergoing ECP, they have pneumatic stockings (also known as cuffs) on their legs and are connected to telemetry monitors that monitor their heart rate
and rhythm. The most common type in use involves three cuffs placed on each leg (on the calfs, the lower thighs, and the upper thighs (or buttock)). The cuffs are timed to inflate and deflate based on the individual's electrocardiogram. The cuffs should ideally inflate at the beginning of diastole and deflate at the beginning of systole
. During the inflation portion of the cycle, the calf cuffs inflate first, then the lower thigh cuffs and finally the upper thigh cuffs. Inflation is controlled by a pressure monitor, and the cuffs are inflated to about 300 mmHg.
When timed correctly, this will decrease the afterload that the heart has to pump against, and increase the preload that fills the heart, increasing the cardiac output. In this way, ECP is similar to the intra-aortic balloon pump (IABP). Since it increases pressure in the aorta
while the heart is relaxing (during diastole) ECP also increases blood flow into the coronary arteries, which also occurs during that phase.