Cuff therapy boosts growth factor. (Biomedicine).

In many patients, a therapy in which inflatable cuffs placed on each leg squeeze blood back up to the heart can relieve angina, or chest tightness. Although physicians have used this so-called enhanced external counterpulsation therapy for nearly 50 years, the mechanism by which it alleviates angina has never been fully explained.

Researchers in Japan now report that counterpulsation therapy increases the amount of a protein called hepatocyte growth factor, or HGF, in a patient's blood. Growth factors help build new blood vessels needed to nourish oxygen-starved heart muscle in patients with angina and other cardiac disease.

The blood concentration of HGF rose by an average 26.6 percent in patients getting the treatment, according to physician Daisuke Masuda and his colleagues at Kyoto University Graduate School of Medicine.

Because the protein was first discovered in the liver, HGF is named for liver cells, or hepatocytes. Researchers subsequently found HGF in the heart, as well.

A patient receiving counterpulsation therapy wears chest sensors that register the heartbeat. Coordinating with the heartbeat, three cuffs worn on each leg squeeze in succession, lowest to highest on the leg. This sequential contracting "milks the blood out of the legs" and back to the heart, says William E. Lawson, a cardiologist at the State University of New York-Stony Brook, who presented the findings for Masuda. The pressure applied to the legs feels similar to that caused by a cuff strapped around the arm during blood pressure testing.

The researchers gave 11 angina patients 1 or 2 hours of counterpulsation therapy daily until all had had 35 hours of treatment. Blood tests taken before and after the therapy indicated increases in HGF in seven of the patients.

This study and earlier work showed that the therapy also boosts blood concentrations of nitric oxide, which dilates vessels.

Counterpulsation therapy has an even more direct effect on patients' hearts, Lawson says. The cuffs push blood into parts of the heart muscle where it's in short supply because of coronary artery blockage. While not everyone gains from the therapy, researchers have shown that a series of treatments can reduce angina in patients for years, he says.

Many cardiologists use the technique only after trying to open patients' arteries with coronary angioplasty, rerouting them with bypass surgery, or clearing them with medication, Lawson says. The new finding suggests that this therapy should be offered earlier in the treatment cycle and to more people, he says.