FRIDAY, Feb. 20, 2009 (HealthDay News) -- Tiny tubes called stents, used for years to open blocked coronary blood vessels, may also work well to reopen brain blood vessels clogged from strokes, according to new research.
A variety of other advances promise to improve stroke treatment or prevention as well, a panel of researchers said. Among the developments, presented Thursday at the International Stroke Conference in San Diego:
- Using new delivery systems to make a medication more effective in breaking up clots in the brain;
- Finding new genetic clues to predict who might develop an aneurysm, a weakened brain blood vessel that can rupture and cause a devastating hemorrhagic stroke;
- Treating people who have low cholesterol levels but elevated levels of a stroke-linked inflammatory marker with the anti-cholesterol drug Crestor, which nearly halved users' risk for stroke in a recent trial.
First, the stent research. According to Dr. J. Mocco, clinical assistant professor at the University at Buffalo, N.Y., the use of a tiny, self-expanding stent seems to be an effective and safe way to reopen blood vessels blocked after an ischemic stroke. Ischemic strokes make up the majority of attacks and occur when a blood vessel is blocked.
The FDA-approved pilot study involved 20 stroke patients averaging 63 years of age, all of whom had no blood flow through the affected brain blood vessel after the stroke. However, after the stent was put in place, "all had adequate blood flow," Mocco said.
Some also received the powerful clot-busting drug tissue plasminogen activator (tPA), in use since 1996. While the time window for tPA usefulness is within three hours of the onset of stroke symptoms, Mocco said he achieved success in reopening vessels when inserting stents up to about eight hours after the onset of stroke symptoms.
Stroke-linked disability also lessened with the use of the stents, he added. "Forty-five percent of the patients achieved complete independence," Mocco said. Other stents have been studied in the brain, he said, but Mocco believes this is the first study to follow patients over time.
Next up came a study investigating the use of ultrasound to boost the effectiveness of tPA. Dr. Andrei Alexandrov, director of the Comprehensive Stroke Center at the University of Alabama in Birmingham, said his team is working to refine the technique.
"Ultrasound energy amplifies the energy of the tPA," Alexandrov explained. In his clinic, he is using ultrasound waves to push tiny, gas-filled fat microspheres containing a contrast agent through the blocked arteries to help reopen the vessels. "The microspheres help tPA continue its mechanical action," the researcher explained.
Comparing 35 patients treated with the microspheres plus tPA or tPA alone, 67 percent of those who got the low dose of microspheres had reopened vessels 36 hours later, compared to 33 percent of those who got tPA alone. Disability seemed reduced as well: 75 percent of those receiving the low-dose ultrasound-boosted treatment had little or no disability within three months of treatment compared to 36 percent of those who got tPA alone. The study was funded by ImaRx Therapeutics, Inc., the maker of the technology.
In other research, using a catheter to deliver tPA for treating brain bleeds was effective in patients with an intracerebral hemorrhage, or bleeding inside the brain. Using tPA to counter a bleed appears "counter-intuitive," acknowledged the lead researcher, Dr. Daniel F. Hanley, a neurology professor at Johns Hopkins Hospital in Baltimore. That's because the clot-buster is meant for ischemic strokes, in which the vessel clogs from within due to a clot, not hemorrhagic strokes, in which the vessel bursts and blood escapes.
However, bleeding within the brain's internal cavities poses its own clotting risk. After someone suffers an intracerebral hemorrhage, clots can form in the areas that fill with blood, Hanley explained. Delivering tPA via catheter to these regions can help dissolve the clots.
In the study, Hanley gave tPA by catheter to 52 stroke patients and followed up to see if they had disability six months later. "Fifty percent of the patients were living independently in the home by themselves at 180 days," he said.
In another study, Yale University researchers report they have found two genetic locations associated with developing aneurysms, the weakened blood vessels that can trigger a potentially deadly rupture. The hope is to someday develop a blood test to identify those at risk, said Dr. Murat Gunel, professor of neurosurgery and neurobiology at Yale's School of Medicine in New Haven, Conn.
And in updated results from a clinical trial published in November in the New England Journal of Medicine, Harvard researchers found that giving a statin drug to people with low levels of cholesterol but increased levels of the inflammatory biomarker C-reactive protein appears to cut their stroke risk almost in half.
"We have further evidence for the efficacy of statins in the prevention of stroke," said Dr. Robert Glynn, associate professor of medicine and biostatistics at Harvard School of Public Health, Boston.
Glynn said that the drug rosuvastatin (Crestor) reduced stroke incidence in those who took it by 48 percent compared to the comparison group who got placebo. AstraZeneca, the drug's maker, funded the study.
Looking over the studies presented at the session, the panel's moderator said that innovations in delivering tPA appeared especially exciting.
Dr. Cheryl Bushnell, associate professor of neurology at Wake Forest University, Winston-Salem, N.C., said that "the safety has already been established [for tPA]," and estimated that new techniques could be widespread in hospitals in five years or so.
More information
Learn to recognize the warning signs of stroke at the American Heart Association.
