Clot Crusher

New tool vacuums blockages in those facing angioplasty

MONDAY, May 6, 2002 (HealthDayNews) -- In a scene reminiscent of the movie "Fantastic Voyage," scientists in Austria have successfully completed a trial in which they used a miniature device to break up and remove blood clots in patients about to have angioplasty.

The new procedure, which appears in tomorrow's issue of Circulation, may improve the odds of survival for these heart patients, the researchers say.

This was the first randomized trial of the device, called an X-sizer.

Angioplasty and stenting are routine procedures in patients who have had a heart attack or unstable angina (chest pain). Angioplasty involves inserting, then inflating, a balloon-shaped catheter into the blocked artery. Stenting involves inserting a wire-mesh tube to keep the artery open.

The danger of the procedures is that blood clots can be dislodged to travel elsewhere in the body, where they can again block blood flow and cause a heart attack or stroke.

The X-sizer suction procedure (called a thrombectomy) removes the clot before the other procedures are performed.

"Our hypothesis was that pre-treatment with the X-sizer would remove clots before performing conventional stent implantation," says study co-author Dr. Peter Siostrzonek, an associate professor of medicine in the department of cardiology at the University of Vienna.

Dr. William Herzog Jr. is associate professor of medicine and acting director of the cardiac catheterization laboratory at the University of Maryland School of Medicine in Baltimore. He says the Austrian researchers "are addressing a very real problem in the management of acute myocardial infarction [heart attack] patients. It's also rare for this kind of study to be randomized. They deserve a lot of credit."

The X-sizer is a rotational cutting-and-suction device that removes soft material from blocked coronary vessels. It?s threaded through the blood vessels, much like a catheter in angioplasty. However, the X-sizer performs two functions: a catheter with a helical cutter on the tip breaks up the blood clot while a tiny vacuum system in a second channel sucks up the pieces.

The treatment takes only 10 to 20 minutes longer than angioplasty, the doctors report, and the device can be set up in seconds.

In this trial, Siostrzonek and his colleagues got ST-segment scores, a measure of heart function, in patients who underwent the procedure.

A person who has had a heart attack has a high ST-segment score. A rapidly decreasing score after a heart attack indicates that blood flow is returning to normal.

"T-segment resolution is a useful predictor for recovery of myocardial function and survival," Siostrzonek says.

The researchers randomly assigned 61 people who had suffered a heart attack or had unstable angina to receive either the X-sizer therapy plus angioplasty or angioplasty alone.

"ST-segment resolution after treatment was significantly improved in 83 percent of patients treated with X-sizer, compared to 52 percent in patients with conventional treatment," Siostrzonek says. Blood flow was also improved in the body's smaller vessels.

The X-sizer is already in use in Europe, but has not received U.S. Food and Drug Administration approval in the United States.

A similar device -- the Angiojet catheter -- has been approved in this country. The Angiojet also uses vacuum extraction but, according to Siostrzonek, has no rotating cutter and is driven by a large external console versus a hand-held motor for the X-sizer.

What To Do: The American Heart Association has more information on both angioplasty and stenting.

SOURCES: Peter Siostrzonek, M.D., associate professor, medicine, department of cardiology, University of Vienna, Austria; William Herzog Jr., M.D., associate professor, medicine, and acting director, cardiac catheterization laboratory, University of Maryland School of Medicine, Baltimore; May 7, 2002, Circulation
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