Pulse waves promote vessel growth to ease chest pain

November 12, 2001

ANAHEIM, Calif., Nov. 12 - Delivering measured pulse waves through special thigh and lower leg cuffs promotes the release of chemicals that trigger new blood vessel growth, thereby reducing chest pain, according to new research presented today at the American Heart Association's Scientific Sessions 2001 conference.

This research provides further evidence that the non-invasive technique called Enhanced External Counterpulsation, or EECP, may be a treatment option for individuals with chronic stable angina (chest pain). People with chronic stable angina have episodes of chest discomfort that are usually predictable. They occur with exertion (such as running to catch a bus) or under mental or emotional stress. In treating chronic stable angina, the goal is to restore restricted blood flow to the heart. Sometimes this is done with balloon angioplasty, to open the blocked artery. Other times coronary bypass surgery is performed to create a pathway around the blockage. Both procedures can be effective, but are highly invasive and carry some risk.

This research holds promise that EECP could be an alternative to angioplasty or surgery in treating some of the 6.4 million Americans with angina. Previous research found that it improved exercise tolerance and relieved chest pain in those with chronic stable angina. Studies have suggested that the technique can stimulate the development of tiny blood vessels known as "collaterals" that carry blood around blocked arteries and restore flow to the oxygen-deprived area of the heart. However, it is difficult to prove the development of collaterals with an X-ray examination of the blood vessels (angiography) because they are so small. The exact mechanism by which the technique exerts its beneficial effects is unknown.

Researchers hypothesized that EECP promotes a process called "shear stress" that spurs the release of blood vessel-growth factors, called angiogenesis factors. New blood vessels improve blood flow and ease the heart's workload. The pulsation therapy decreases systolic blood pressure - the top number in a blood pressure reading, which records the pressure of blood flow when the heart beats. At the same time, it increases diastolic blood pressure - the bottom number, which is the pressure between beats. This unusual wave pattern induces shear stress, says Daisuke Masuda, M.D., Ph.D., a postdoctoral fellow in cardiovascular medicine at Kyoto University Graduate School of Medicine, Kyoto, Japan.

"Several angiogenesis factors are necessary for the development of functional collateral vessels, and the major trigger to release angiogenesis factors is considered to be shear stress. Therefore, our study was proposed to determine if EECP promotes the release of angiogenesis factors," says Masuda.

In a previous study, this team proved that collateral vessels developed with EECP are functional.

In the study, 11 individuals with chronic stable angina were treated with the technique once or twice each day in one-hour sessions, for a total of 35 sessions. The average age of participants was 61.

A series of cuffs similar to those used to gauge blood pressure are placed around the patient's legs. Following each heartbeat, a computer inflates the cuffs, which forces blood through the coronary arteries. Each time the cuffs deflate, a slight vacuum is created within the arteries, which also moves blood. This creates a milking action that moves blood from the legs upward to the heart.

Researchers measured blood levels of four known angiogenic factors called VEGF, HGF, bFGF and MCP-1 before and after therapy. Three of the chemicals increased after therapy: HGF by 26.6 percent; bFGF by 18.8 percent and VEGF by 15.6 percent. The chemical MCP-1 did not increase.

Results suggest that EECP therapy promotes angiogenesis factors through shear stress that results in the development of collateral vessels.

"These results should be considered a ray of hope for patients with symptomatic coronary artery disease who have not responded to traditional medications and repeat interventions, including coronary bypass grafting," Masuda says. "Unlike bypass surgery and balloon angioplasty, EECP is non-invasive and administered in inpatient and outpatient sessions. The therapy carries minimal risk and is relatively comfortable.

"Although this study was small, it is important that this study proved how EECP therapy developed functional collateral vessels and supported our previous report," he notes.

Other researchers are: Ryuji Nohara, M.D., Ph.D.; Kazuaki Kataoka, M.D., Ph.D.; Ryohei Hosokawa, M.D., Ph.D.; Naoshige Kambara M.D.; and Masatoshi Fujita M.D., Ph.D.
-end-
CONTACT:
For other information Nov. 10 -14, call: Carole Bullock or Bridgette McNeill at the Hilton Anaheim Hotel
(714) 251-5801

NR01-1355 (SS2001/Masuda)

American Heart Association

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