Opening of Kidney Arteries Brings Dangers

Microscopic 'debris' is left behind with these angioplasties, study finds

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HealthDay Reporter

FRIDAY, June 29, 2007 (HealthDay News) -- Angioplasty and stenting can open blocked kidney arteries, but the procedure also throws off an immense amount of debris that can hurt kidney function, a new study shows.

It has been known that this procedure -- done primarily to relieve high blood pressure -- is messy, but "this is the first paper in humans to really demonstrate how much stuff there is and especially how much microscopic material there is," said Dr. Matthew Edwards, an assistant professor of surgery at Wake Forest University Baptist Medical Center and lead author of a report in the June issue of the Journal for Vascular Surgery.

Angioplasty and stenting for blocked kidney arteries involves the insertion of a balloon to open the artery, followed by the implantation of a tube to keep it open. The procedure doesn't get as much attention as a similar surgery done for heart vessels, but an estimated 40,000 to 80,000 Americans receive this intervention each year, Edwards said. The operation's primary purpose is to lower blood pressure caused by a blockage, and its ultimate goal is to prevent kidney failure, he said.

The new report described 28 angioplasty cases in which the physicians took blood samples after a stent was implanted.

Laboratory analysis revealed an average of 2,000 debris particles in the blood samples -- some pieces being big enough to block smaller vessels in the kidney.

The number of particles found in specific patients was directly related to their subsequent kidney function, the researchers found: more debris, worse kidney function.

That can bode ill for patient's longer term health, Edwards said, since "poor kidney function after kidney artery stenting has been previously demonstrated by our group to be associated with increased risk of heart attack, stroke or death in the future."

Post-angioplasty debris was also found to float freely in arteries, even though the surgeons used a protective device designed to trap it for removal. The Wake Forest surgeons used one of several protective devices now being tested. None have yet been approved by the U.S. Food and Drug Administration.

One or another of these protective devices may someday go into medical practice, Edwards said. "We certainly need a protection device," he said. His group used one designed by Medtronic. It is essentially a large balloon that traps the debris so that it can be collected and removed when the procedure is finished.

But Edwards also noted that certain kinds of fatty plaques could create more debris than others.

"The plaques that sit in these arteries are not all the same," he said. "Some might be prone to liberate more debris than others."

Edwards hopes that, in the future, this most dangerous form of debris could be identified before a procedure is done.

"There has been some work on that in the carotid artery," Edwards said, referring to the main artery to the brain. "Some MRI and ultrasound studies have identified plaque that is prone to release more debris."

Edwards said his group now is conducting a trial to explore that possibility.

More information

There's more on kidney angioplasty at the University of Southern California.

SOURCE: Matthew Edwards, M.D., assistant professor, surgery, Wake Forest University Baptist Medical Center, Winston-Salem, N.C.; June 2007 Journal for Vascular Surgery

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