This should increase public awareness of ECP - a front section article in this morning's Post. Generally a positive review, but it seems that I've read of far more research studies than the article cites.
washingtonpost.com
Better Blood Flow In Just a Shake
'External Counterpulsation' Holds Out Hope for Aiding Angiogenesis
By David Brown
Washington Post Staff Writer
Tuesday, July 24, 2001; Page A07
It certainly doesn't look like a good activity for someone with a bad heart.
First, you're strapped to a table, fitted into a pair of inflatable pants and wired up to an EKG machine. Then, for about an hour, every time your heart beats the pants inflate, squeezing your legs, shaking your body and making a lot of noise.
The procedure is called external counterpulsation (ECP) and is one of cardiology's hottest new treatments, albeit of unproved worth. Proponents believe it may be a low-tech route to what was once believed an once-impossible goal: stimulating the heart to grow new blood vessels.
"This therapy was laughed at by cardiologists for years. It's like something out of a Rube Goldberg cartoon," said Harry A. Oken, chief of medicine at Howard County General Hospital, who urged his institution to get an ECP machine in 1997, the first in the Washington area.
The treatment typically consists of 35 hour-long sessions, stretched over seven weeks. In 1999, Medicare decided to cover the procedure, and the number of people undergoing it has risen sharply. This year, about 4,000 people will have ECP, about double the number who did in 2000. The treatment costs $5,000 to $8,000, depending on who's paying.
There are more than 200 sites where ECP is performed. A setup costs about $200,000. Sales doubled last year at the manufacturer with the biggest market share, Vasomedical, of Westbury, N.Y., according to a company spokesman.
ECP is intended for people with coronary heart disease who have exhausted conventional therapy: Bypass surgery has been done (or can't be done), angioplasty isn't possible and medicines aren't enough to quell the chest pain.
To understand how it works, it helps to know a little about the mechanics of the heart.
Since the heart muscle is constantly working, it has a big demand for oxygen-rich blood. That comes from two vessels, the coronary arteries, which branch off the aorta immediately after that hose-sized vessel exits the heart.
Paradoxically, most of the blood flow into the coronaries occurs between beats, when the heart is relaxed. During that pause -- it lasts less than one second -- the aorta, which is literally bulging with blood, relaxes and in so doing propels blood into the arbor of branches coming off it.
ECP increases coronary blood flow by raising the pressure in the aorta during the pause between beats. At the instant the pause begins, the pneumatic pants inflate -- first around the calves, then the thighs, then the buttocks. At the instant the heart starts to contract, the pants deflate.
The procedure squeezes more blood into the coronary arteries, which makes many people with coronary artery disease feel better. But it apparently does more than that. The higher pressure -- it's about twice what normally exists between beats -- appears to initiate a cascade of changes in the cells lining the coronary arteries.
The changes are similar to what happens with aggressive physical training, and in fact ECP may be the closest thing to truly passive exercise. One of the results is increased secretion of vascular endothelial growth factor (VEGF), a hormone that stimulates blood vessel growth, or angiogenesis.
"It's unclear that angiogenesis is the primary mechanism, but it certainly may play a role," said Gregory Barsness, a physician at the Mayo Clinic in Rochester, Minn., who has studied ECP.
Whatever it is, Barbara Mendenhall thinks it works.
Mendenhall, 65, is a retired elementary school teacher in Columbia whose coronary artery disease is not amenable to surgery. Midway through a treatment -- four one-hour sessions a week, for seven weeks -- she proclaimed ECP a success already.
"I'm not as tired," she said. "Whereas before I could only do one strenuous thing a day, now I can do two or three. I just feel better."
She spoke over a relentless sound of chuff poof, chuff poof as the air bladders in the ECP pants inflated and deflated. Every round shook her body. When she laughed and her pulse rate sped up, so did the pants. The effect, originally scary and disconcerting, no longer bothers her.
"I look like I'm in a straitjacket, but I'm really quite comfortable," she said. "Sometimes, I go to sleep."
A case that particularly impressed Oken occurred last year.
A 61-year-old man who had had two bypass operations and several angioplasties once again developed chest pain. During a test known as cardiac catheterization, the doctors saw a coronary vessel that could potentially be widened with angioplasty. But there wasn't an adequate "collateral" system of blood vessels that could feed the heart muscle if a calamity occurred and angioplasty closed off the vessel rather than opened it.
Oken advised against the procedure, and suggested the man try ECP instead. He got two seven-week courses. The therapy reduced, but did not eliminate, his chest pain.
In February, the man underwent cardiac catheterization. The growth of new collateral blood vessels was dramatic, Oken said. With them, the risks of angioplasty seemed reasonable, and the man underwent the procedure. Now, he walks 2 miles a day, and though he occasionally gets chest pain with extreme exertion, he feels far better than before.
Many such anecdotes surround ECP. However, proving that the therapy stimulates vessel growth -- or even works for certain, beyond some placebo effect -- is another matter.
Only one randomized controlled trial -- the best way to judge effectiveness -- has been done. It showed that people getting a 35-session course of ECP were able to exercise longer, and had fewer episodes of chest pain, than people who got a "sham," or fake, form of the procedure. The study did not include examining patients for signs of angiogenesis.
"Limited data from a small number of patients followed for five years suggest that those who respond to treatment are less likely to experience cardiac events that those who did not respond to treatment. However . . . intervening variables may have affected outcomes," said reviewers at ECRI, a nonprofit health technology assessment service in Pennsylvania, which recently published a review of ECP research.
Barsness, the Mayo Clinic researcher, said a study is underway that may help answer the angiogenesis question.
Before and after getting ECP, patients will undergo imaging studies that depict blood flow to the heart muscle. Then, physicians who don't know which image is which will evaluate them and judge whether the blood flow patterns are different.
© 2001 The Washington Post Company |
