Clear the Way: Stenting opens jammed arteries in the brain
By pushing a tiny mesh cylinder called a stent through blood vessels leading from the groin to the head, doctors can prop open narrowed arteries in the brain much as they do in the heart, several new studies show.
A brain artery that’s partially blocked because of atherosclerosis is a stroke waiting to happen. While blood thinners such as aspirin and warfarin can ease blood flow through narrowed brain vessels, roughly one-fifth of patients with severe narrowing who get these drugs still suffer a stroke or brain hemorrhage or die of a vascular problem within 2 years.
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Seeking a better alternative, scientists have adapted stents to fit brain arteries, which are smaller and more fragile than the arteries serving the heart. Two studies presented last week at the 2007 International Stroke Conference in San Francisco, along with a trial reported last year, indicate that the still-experimental brain stents might work as well or better than drugs and have fewer adverse effects.
In one of the studies reported in San Francisco, Chinese researchers placed bare metal stents in the brains of 213 people who had had a stroke or ministroke in response to atherosclerosis that had reduced the diameter of a brain artery by more than half. Only about 9 percent of the patients experienced a stroke in the stented artery during the 2 years following stent placement, says Wei-Jian Jiang, a cardiologist at Beijing Tiantan Hospital.
In another study, U.S. researchers analyzed data on 131 patients who had a brain artery 82 percent occluded, on average. Most had already suffered a stroke or ministroke. All received a newer, more flexible stent that springs open at the target site. The device reduced the average size of the occlusion to 20 percent, says study coauthor Osama O. Zaidat, a neurologist at the Medical College of Wisconsin in Milwaukee.
In a third study, published in the October 2006 Stroke, only 2 of 59 patients with severely narrowed brain arteries experienced strokes during the 4 months after they received drug-coated metal stents. There were few other complications, and almost all the stented arteries remained open, says study coauthor Tudor G. Jovin, a neurologist at the University of Pittsburgh Medical Center.
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The studies establish that stents can be placed inside the brain and dramatically improve blood flow, Zaidat says. The next step will be an efficacy trial in which the researchers randomly assign some of the participants to get a stent, he says.
Brain stenting is a new science. It’s still not clear which stent works best, says Jovin. “We’re going through what cardiology went through 10 or 15 years ago,” he notes. Learning to insert the stent takes time because the head’s blood vessels “are very tortuous, and there are long distances you have to traverse,” Jovin says.
Some people are cautiously optimistic. “These are good devices,” says Robert J. Adams, a neurologist at the Medical College of Georgia in Augusta. “But if you don’t have the data on their efficacy, the story’s not complete.”