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Squeezing the Pain Away

By Paul Candon

A P&S researcher has demonstrated that the pain of angina pectoris can be relieved without medication or invasive procedures.
A P&S researcher has demonstrated that the pain of angina pectoris can be relieved without medication or invasive procedures. A series of compressive cuffs, which squeeze the legs each time the heart is relaxed, relieved or reduced pain in two-thirds of angina patients studied.

"The beauty of this device is that it is helpful in two-thirds of the patients. The side effects are minimal, occurring less than 5 percent of the time, and generally involve mild skin abrasions to the legs," says Dr. Rohit Arora, associate professor of clinical medicine and primary investigator in the study. "Most patients are able to tolerate this device. This is a great option at the present time."

A narrowing or obstruction of the coronary arteries can cause angina, temporary chest pain experienced during exercise or stress. The pain is a result of insufficient oxygen-enriched blood reaching the heart at these critical times. Patients typically receive medical treatments, such as nitroglycerin and calcium antagonists, or invasive procedures, such as angioplasty and bypass surgery. These options are effective, but potentially adverse side effects and the inherent risks of surgery make them less than ideal.

Dr. Arora spearheaded the first multicenter, placebo-controlled study of enhanced external counterpulsation (EECP), a non-invasive treatment for angina. The main goal of EECP is to increase blood flow to the heart by raising diastolic blood pressure. Although most arteries fill when the heart contracts, the coronary arteries fill during diastole when the heart is relaxed. The technique is relatively straightforward. First, the patient lies down on a padded table and has adjustable pneumatic cuffs, similar to blood-pressure cuffs, wrapped around the calves, lower thighs, upper thighs, and buttocks. Heart rate and blood pressure are monitored by the EECP system. During diastole, the cuffs are inflated sequentially from the calves upward. With systole, the cuffs are all simultaneously deflated, allowing normal blood flow to the legs. This counterpulsation procedure, so called because it works opposite the pulsation of the heart, forces a wave of blood pressure from the legs upward toward the heart just as the coronary arteries are naturally filling. As a result, more oxygen-enriched blood flows through the coronary arteries.

"The whole idea is to increase the blood flow during diastole. That's when most of the filling of the blood vessels of the heart occurs," Dr. Arora says.

During the study, patients underwent 35 hours of EECP. The sessions lasted one hour each and were conducted Monday through Friday for seven weeks. A placebo group received a treatment similar to EECP, but the pressure in the cuffs was kept low enough to avoid altering blood pressure.

Compared with placebo, the efficacy of EECP was clear. Two-thirds of those who received the EECP treatment benefited. It was effective in reducing chronic angina for patients with both mild and severe conditions. "We found that patients did get relief of their chest pain. Also, their exercise performance was better on the treadmill test," Dr. Arora says. The study was published in the June 1999 issue of the Journal of the American College of Cardiology.

In addition, the benefits of the therapy appear to outlast the treatment regimen itself. At a 12-month follow-up, the EECP patients reported being more mentally and physically fit and having a lower incidence of angina. No clear evidence exists to explain the physiological mechanism underlying EECP's long-term effectiveness, but Dr. Arora suspects that by constantly filling the coronary arteries with oxygen-enriched blood the therapy stimulates collateral cardiac branches to grow. He hopes to uncover the specific mechanism with further research.

With the completion and success of the EECP study, Dr. Arora has increasingly given the treatment as a clinical option for angina patients. He feels it is a particularly good treatment for patients whose medications have not succeeded in reducing pain or for patients who are not good candidates for surgery because of potential complications. If research proves the therapy to be as effective as medicine or surgery at reducing angina symptoms, it has the potential to become the primary treatment option.

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