Blood-diverting catheter holds promise for stroke treatment
American Stroke Association meeting report
SAN DIEGO, Feb. 5 – A new catheter device that diverts some blood from the lower body to the brain appears safe for treating acute stroke and may significantly reduce stroke complications – even after a critical treatment window has lapsed.
The results of this experimental study were reported today at the American Stroke Association's 29th International Stroke Conference.
"The device treats stroke by a unique approach that increases blood flow to the brain," said lead author Morgan S. Campbell III, M.D., director of interventional neurology at the Alabama Neurological Institute, in Birmingham. "Ten of the 15 patients who were conscious when they arrived at the hospital improved during the procedure, which is very impressive."
Campbell and his colleagues tested the safety and effectiveness of the device, called NeuroFlo, on patients who suffered ischemic strokes. Ischemic strokes occur when a blood clot blocks an artery, reducing blood flow and oxygen to part of the brain. Using two balloons attached to a catheter, NeuroFlo diverts some blood from the lower extremities and sends it to the upper body.
Not all the brain cells affected by an ischemic stroke die immediately, Campbell said. A large number of cells in the stroke area initially have the potential to recover if their blood supply is restored. In theory, increasing the volume of blood to these damaged brain cells should preserve some of them even more than three hours after a stroke onset.
Ischemic stroke patients who arrive within three hours of symptom onset can often be treated with clot-busting drugs. However, these clot busters are not recommended for use more than three hours after stroke onset.
"The blood volume theory has been studied before but no one had really shown that it actually works and makes a difference," Campbell said. "So it is very encouraging that the device can divert more oxygenated blood to the brain and that patients get better."
Campbell conducted the study while he was an assistant professor of neurology and radiology at The University of Texas Health Science Center at Houston. He and colleagues at eight medical centers in the United States, Turkey, Germany and Argentina studied 17 patients whose strokes had been in progress for three to 12 hours. The average time between stroke onset and the beginning of treatment was 7.5 hours.
Each patient had a NeuroFlo device inserted into an artery in the groin. The device was then threaded up to the abdominal aorta and positioned with collapsed balloons above and below the renal arteries. The balloons were then inflated to partially obstruct the aorta. The device was left in place for one hour.
"By blowing up these balloons and limiting the blood flow to the lower extremities, we shifted more of the blood flow up to the head," Campbell explained.
This greater volume of blood increased collateral flow, the flow of blood through smaller vessels in the brain. The collateral flow by-passed the blocked section of the artery that was causing the patient's stroke, and brought needed oxygen to the cells downstream from the blockage.
The study's primary intent was to test the device's safety. Although two study participants died, their deaths were attributed to their strokes and not adverse effects of the device. Nor did people treated with the device suffer damage to their kidneys, heart or blood vessels.
The research team also evaluated the patients' treatment response.
Twelve of 16 patients monitored with ultrasound had a 15 percent increase or more of their cerebral blood flow velocity, with an average boost of 25 percent. Ultrasound waves passing into the skull can measure blood flow velocity. Velocity is an indirect measure of blood flow volume.
The blood pressure in the arteries increased an average of only 6 percent overall and did not increase in five patients. "This shows the increased blood flow did not simply result from an increase in blood pressure but from an increase in blood volume," Campbell said. "This is the desired effect of the device."
The researchers also assessed the degree of deficit of the stroke patients. While undergoing their hour-long treatment, 10 of the 15 conscious patients (67 percent) showed significantly higher scores on the National Institutes of Health Stroke Scale, the most commonly used assessment tool in acute stroke. Thirty days after treatment, six of the 15 survivors had "good" physical function, on the modified Rankin scale, which rates disability.
The second phase of the study has begun enrollment. CoAxia, Inc., the device's maker, will seek approval from the U.S. Food and Drug Administration to conduct a larger clinical trial.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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