Enhanced external counterpulsation for ischemic heart disease
What’s behind the curtain?
Piero O. Bonetti, MD*,
David R. Holmes, Jr, MD, FACC*,
Amir Lerman, MD, FACC* and
Gregory W. Barsness, MD, FACC*,*
* Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota, USA.
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Figure 1 Principle of enhanced external counterpulsation. Three pairs of pneumatic cuffs are wrapped around the calves, lower thighs, and upper thighs. During early diastole, these cuffs are inflated sequentially from distal to proximal, resulting in a "milking effect" of blood from the lower extremities. At the onset of systole, all cuffs are deflated, resulting in acute afterload reduction. Modified from the October 2001 Mayo Clinic Health Letter. Copyright Mayo Foundation for Medical Education and Research. All rights reserved. Used with permission.
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Figure 2 Electrocardiogram (upper panel) and finger plethysmographic recording (lower panel) after initiation of enhanced external counterpulsation (EECP). Enhanced external counterpulsation leads to an increase in diastolic pressure (diastolic augmentation) and a decrease in systolic pressure (systolic unloading). The magnitude of EECP-induced hemodynamic changes is commonly assessed by measuring the diastolic-to-systolic effectiveness ratio, which is calculated by dividing the peak diastolic amplitude by the peak systolic amplitude of the finger plethysmographic signal.
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Figure 3 Possible mechanisms responsible for the clinical benefit associated with enhanced external counterpulsation (EECP). Acute afterload reduction decreases myocardial demand. By increasing coronary blood flow, EECP is thought to promote myocardial collateralization via opening of preformed collaterals, arteriogenesis, and angiogenesis. Increased blood flow and shear stress may also improve coronary endothelial function favoring vasodilation and myocardial perfusion. In addition, improvement in endothelial function may further promote collateral formation by arteriogenesis and angiogenesis. Besides a peripheral training effect, a minor placebo effect is considered to contribute to the symptomatic benefit of EECP. ET = endothelin; NO = nitric oxide.
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