The same kind of sound waves that allow expectant mothers to see their unborn children also may provide assistance in busting stroke-causing blood clots. Researchers at the Oregon Health Sciences University's Oregon Stroke Center are testing the effectiveness of ultrasound-enhanced drug delivery for patients within the first few hours of suffering a stroke. The School of Medicine and Biomedical Sciences in Buffalo New York and the Vancouver Hospital and Health Sciences Center in British Columbia also are taking part in this clinical trial. Early results of this new therapy will be presented at the American Society for Neuroradiology Conference today.
The clinical trial involves the use of a specially designed catheter made by EKOS Corporation in Bothell, Wash. This catheter allows for the simultaneous delivery of ultrasound waves and the drug t-PA directly to the stroke-causing blood clot. Of the 14 patients who have taken part in this clinical trial, approximately two-thirds experienced complete or partial breakdown of the blood clots causing their strokes. Three months after treatment, almost half of these patients showed significant enough recovery to be able to operate independently.
"The drug t-PA is the only FDA-approved medication for the treatment of ischemic stroke, which is a stroke caused by a blood clot. The clot causes a loss of blood supply to portions of the brain, which can result in brain damage," said Wayne Clark, M.D., director of the Oregon Stroke Center and a professor of neurology in OHSU's School of Medicine. "The drug has been somewhat successful in treating patients who come into the hospital in the first three hours after suffering a stroke. With the use of ultrasound, we're hoping to improve the effectiveness of t-PA and lengthen the window of time for its use."
After three hours t-PA's effectiveness drops, and the drug can actually increase the chance of serious cranial bleeding. The current clinical trial involves patients seeking treatment from three to 24 hours after the onset of symptoms. This window of opportunity varies depending on the area of the brain affected.
Each year 550,000 Americans suffer a stroke. It is the third leading cause of death in this country with a total of 150,000 deaths a year.
The Oregon Stroke Center at OHSU is recognized as a national leader in research and patient care. The center is home to a mobile stroke team available 24 hours a day to treat patients at five Portland-area hospitals in the critical early stages of a stroke. Providence St. Vincent Hospital, Providence Portland Hospital, Legacy Emanuel Hospital, Portland VA Medical Center and OHSU are partners in the stroke team.