Posts Tagged 'telestroke'

Advances in thrombolysis

Bill Likosky, MD, FAAN, FAHA, Director for Stroke and Telestroke, Swedish Neuroscience Institute

 

 

Washington State has one of the high­est stroke mortality rates in the nation. To improve this situation, acute intervention­al therapies for stroke are being employed to restore circulation to ischemic brain tissue that surrounds areas of completed infraction, while avoiding risk of hemor­rhage due to reperfusion of large areas of infracted brain tissue.

Urgent thrombolysis with intrave­nous alteplase is the only therapy known to improve clinical outcomes following acute stroke. Unfortunately, alteplase has had limited usage because many patients arrive in an emergency department after the three-hour treatment window. The FDA has also approved two clot removal devices based on the ability to restore circulation. These devices are used up to eight hours after symptom onset. Several approaches to improved acute stroke care are now under way, including extension of the thrombolysis window to 4.5 hours, identification of safer thrombolytic agents and research identifying brain at risk of in­farction following a stroke.

A recent European study demonstrat­ed the efficacy of alteplase up to 4.5 hours after ischemic stroke in patients younger than age 80 years who have neither dia­betes mellitus or prior stroke. The safety profile during this longer window for these patients appears similar to that at three hours.

Another promising advance employs a new thrombolytic agent called des­moteplase. Derived from the saliva of the vampire bat, this agent has a longer half life than alteplase and does not break down basement membranes, leading to a lower risk of hemorrhagic complica­tions. The Swedish Stroke Program is part of an international effort to test this drug in a nine-hour window.

Todd Czartoski, M.D., and Bart Keogh, M.D., Ph.D., are collaborat­ing with the stroke team at Stanford University to identify patients with vi­able ischemic tissue regardless of time from onset of symptoms. Perfusion MRI identifies impaired blood flow in brain (the “penumbra”) surrounding an infarct. In cases where there is a large area at risk, the use of alteplase or clot retrieval may prove beneficial long after the three-hour window has elapsed.

Telestroke is another important development in acute stroke care. This program enables the timely alteplase treatment of patients in emergency rooms around the Pacific Northwest that lack onsite neurological expertise.

For more information about the Swedish Stroke Program, contact Sherene Schlegel, R.N., FAHA, at 206-320-3484. For information about telestroke, contact Tammy Cress, R.N., MSN, at 206-320-3112.

Desmoteplase may hold the key for stroke patients

Dan Rizzuto, PhD, Research Manager, Swedish Neuroscience Institute

Acute stroke is the third leading cause of mortality and the major cause of long-term disability in the developed world. Ischemic strokes account for about 85 percent of all acute strokes and are caused by clots that block blood vessels in the brain, stopping the flow of blood to crucial brain areas.

The main approach to treating acute ischemic stroke is thrombolysis, which degrades the clot causing the stroke and provides significant clinical improvements. The only thrombolytic intervention for acute ischemic stroke that is currently approved by the U.S. Food and Drug Administration (FDA) is alteplase. However, alteplase must be administered within three hours after symptom onset to avoid the risk of inducing a hemorrhage in the brain. (More recent evidence supports delivering alteplase up to 4.5 hours.) Because of this time limitation, it is estimated that alteplase is currently administered to less than five percent of acute stroke patients. While this time limitation is a large factor, a high proportion of patients arriving within the appropriate time window still do not receive alteplase due to contraindications (e.g. age, severity, hypertension etc.) or due to the unfavorable risk-benefit ratio.

Recently a new thrombolytic agent, desmoteplase, has been developed that is based upon a protein found in the saliva of the Desmodus rotundus, better known as the common vampire bat. Studies conducted so far suggest desmoteplase breaks down clots efficiently and elicits few side effects, indicating the potential for better clinical outcomes. Importantly, it is possible to administer desmoteplase up to nine hours after symptom onset. Swedish Medical Center is participating in DIAS-4, a new study to assess the safety and effectiveness of desmoteplase.

“This new agent holds great promise,” said William Likosky, M.D., principle investigator for the clinical trial and medical director of the Swedish Acute Telestroke Program. “Currently, we are fortunate to have a network of emergency departments in which alteplase can be administered within an early window. If stroke patients have an initial treatment window up to nine hours, however, we can consider transferring them to medical centers that can provide thrombolysis beyond that available for alteplase.”

This clinical research study to test desmoteplase is being carried out under strict oversight by the FDA. By participating in this study, Swedish continues its tradition of offering the most advanced therapies available to patients who have few other options. In addition, the Swedish Acute Telestroke Program is able to offer this trial to patients outside the Seattle area who are brought emergently to Swedish for treatment.