Thrombolytic (fibrinolytic) drugs help reestablish blood flow to the brain by dissolving the clots, which are blocking the flow. In June, 1996, the “clot-buster” Activase® (Alteplase recombinant) became the first acute ischemic stroke treatment to be approved by the Federal Food and Drug Administration (FDA). Activase is also known as tissue plasminogen activator (tPA). To be effective, thrombolytic therapy should be given as quickly as possible.
tPA is an enzyme found naturally in the body that converts, or activates, plasminogen into another enzyme to dissolve a blood clot. It may also be used in an IV by doctors to speed up the dissolving of a clot. tPA should be given within three hours of symptom onset. It is important for people to understand stroke warning signs and get to a hospital FAST in case they are eligible to receive tPA. Time is an important factor associated with determining whether a patient can receive it or not.
The results of a five-year trial, conducted by the National Institute of Neurological Disorders and Stroke (NINDS) found that carefully selected stroke patients who received Activase within three hours of the beginning of stroke symptoms were at least 33 percent more likely than patients given a placebo to recover from their stroke with little or no disability after three months. The most common complication associated with Activase is brain hemorrhage. However, studies have shown that tPA does not increase the death rate of stroke patients when compared with placebo.
MERCI Retrieval System
In 2004 the FDA cleared Concentric Medical's innovative Merci® Retriever for patients who are ineligible for IV-tPA or fail to respond to IV-tPA. The system can be used for patients who are beyond the 3-hour time window for IV-tPA and it does not have a time limit for its intended use. This device offers physicians and patients long-awaited options for stroke intervention and creates a departure from the historic method of caring for stroke patients. The Merci Retriever has repeatedly been proven to restore blood flow in the larger vessels of the brain by removing blood clots. Over 8,000 patients world-wide have undergone this procedure and it has been performed at over 300 US hospitals. The system is a tiny cork-screw shaped device that works by wrapping around the clot and trapping it. The clot is then retrieved and removed from the body.
At the beginning of 2008 it was announced that the Penumbra System is now available for use. The system allows for safe revascularization of occluded vessels after an ischemic stroke. The system also helps restore brain blood flow by using suction to grab blood clots in the brain for treatment of acute ischemic stroke. For doctors and patients alike, this system is revolutionary. Previously doctors had limited treatment options with acute ischemic stroke if patients were beyond the three-hour window for intravenous thrombolysis. The Penumbra System is a device that is effective if used within eight hours of symptom onset.
For more information on current trials visit:
National Stroke Association's Clinical Trials Resource Center