Phase 1 Early Hyperacute Phase - Treating Ischemic Stroke: Stroke
Content provided by the Faculty of the Harvard Medical School
Phase 1: Early, hyperacute phase
This period spans the first minutes to several hours after stroke symptoms begin. As soon as an ischemic stroke or TIA is diagnosed, the first goal is to determine whether a clot is still blocking an artery and to consider whether to give medication to dissolve the clot.
Thrombolytic therapy
You may be given a clot-dissolving drug (thrombolytic therapy) to dissolve the blockage and restore blood flow to the brain. Drugs of this type, frequently used to treat heart attacks, have been found useful in treating ischemic stroke as well. But they carry the risk of causing a hemorrhage, so doctors must carefully consider whether to use them.
The drug will be given either intravenously through a thin tube in your arm or intra-arterially through a catheter threaded through your blood vessels directly to the site of the blockage.
Intravenous. The drug given for intravenous thrombolytic therapy is recombinant tissue plasminogen activator (tPA), one of the first genetically engineered medications. Intravenous tPA was developed to dissolve small clots by generating the enzyme plasmin, which digests the strands of fibrin that form clots (see Figure 13). When tPA works, its benefit is long term. A study sponsored by the National Institutes of Health showed that although people treated with tPA did not show any improvement after just one month, there was some improvement after three months.
Figure 13: How clot busters work
 Thrombolytic drugs such as tPA are often the first line of defense in treating some forms of ischemic stroke. The blockage forms when fibrin strands in the blood trap blood cells and platelets, forming a clot in an artery to the brain (A). The drug breaks up the clot by helping generate the enzyme plasmin, which digests the fibrin strands, restoring blood flow (B). |
This drug is best given within three hours of the onset of stroke because it can lead to a hemorrhage in the brain if given later. The more time that passes between stroke onset and the administration of tPA, the greater the risk of hemorrhage.
Intra-arterial. This is a different method for delivering clot-busting (thrombolytic) medication, using a catheter placed in the artery near the clot. Either of two drugs can be used — tPA or an older, similar drug called urokinase (Abbokinase). Doctors consider this approach when a major artery appears to be blocked. This method is particularly effective because, in addition to releasing medicine to help dissolve the clot, the doctor can use the tip of the catheter to dislodge it. One study demonstrated its effectiveness when it was used to remove a clot in the major arteries at the base of the brain. This treatment can be used only in the first few hours after a stroke because of the risk of hemorrhage, but in some cases it results in a dramatic recovery within hours. It is best done by a skilled team headed by a stroke neurologist. People who suffer a stroke in the brainstem area have been shown to benefit from this treatment up to six hours after the attack.
Medication to prevent further clots from forming (antithrombotic, or anticoagulant, therapy such as heparin) may also be useful at this stage (see Table 1). It is sometimes given either as an alternative to thrombolytic therapy or after the effect of thrombolytic therapy has worn off.
Table 1: Medications commonly used for ischemic stroke | |||
| Generic name (brand name) | Use | Side effects | Comments |
| Anticoagulants/antithrombotics (drugs that slow blood coagulation) | |||
| heparin | Given to hospitalized people following a stroke, TIA, or heart attack to reduce risk of new blood clots | Bleeding, pain and redness at the injection site, thrombocytopenia (abnormal reduction in number of platelets) | Unsafe for people with bleeding problems. Bleeding complications more likely in older people, especially women, who may be more sensitive to the drug's effects. |
| warfarin (Coumadin) | Used for long-term (six-month) anticoagulation therapy in people who have been discharged from the hospital and are at high risk for another stroke. Especially effective for preventing stroke brought on by atrial fibrillation. | Bleeding from any tissue or organ | Not recommended for people with active ulcers. Blood-clotting time must be measured regularly. Medications such as antibiotics, nonsteroidal anti-inflammatory drugs, and barbiturates may exaggerate the effects of warfarin. |
| Antihypertensives (drugs that lower blood pressure) | |||
| ACE inhibitors: benazepril (Lotensin), enalapril (Vasotec), others | Inhibit angiotensin-converting enzyme (ACE) from activating the hormone angiotensin. Angiotensin signals the body to constrict blood vessels, thereby raising blood pressure. ACE inhibitors dilate arteries, decrease the resistance to blood flow in vessels, and lower blood pressure. | Persistent dry cough; altered taste sensation; rash and other allergic reactions; may cause kidney damage and, rarely, decrease the number of white blood cells | Usually taken once or twice a day; may be used alone or in combination with other medications. |
| Thiazide diuretics: chlorthalidone (Hygroton, Thalitone), hydrochlorothia-zide (Microzide, HydroDIURIL), others | These medications work by reducing the amount of water in the body and increasing the flow of urine; also lower blood pressure. | May lower potassium levels, possibly causing leg cramps; may raise blood sugar and cause fatigue | Often used as first-line therapy for high blood pressure. May be used alone or in combination with another medication. Be aware that diuretics boost the effectiveness of other antihypertensives. |
| Antiplatelets (drugs that discourage blood platelets from sticking to one another and to artery walls) | |||
| aspirin (Bayer, Bufferin, others) | Reduces risk of new blood clots after a stroke, TIA, or heart attack, or in people who have atrial fibrillation and cannot take warfarin | Stomach pain, bleeding, or ulcers | Allergic reactions are uncommon but can occur. Not recommended for people with bleeding problems or active ulcers. |
| clopidogrel (Plavix) | Inhibits the clumping of platelets in the blood to help prevent clot formation | Has fewer gastrointestinal side effects than aspirin but may cause stomach pain or bleeding, dizziness, headache, or intracranial bleeding | Often prescribed for people who cannot tolerate aspirin. |
| aspirin with dipyridamole (Aggrenox) | Reduces the risk of new blood clots after a stroke, TIA, or heart attack | Stomach pain, bleeding, ulcers, diarrhea, nausea | Sometimes prescribed as an alternative to aspirin or clopidogrel alone. |
| Thrombolytics (drugs that dissolve blood clots) | |||
| tPA, recombinant tissue plasminogen activator (Activase) | Breaks down fibrin, the main component of blood clots | Bleeding from any tissue or organ | Must be given intravenously within three hours of ischemic stroke that has been confirmed by a CT scan. Can be life-threatening for people who have had a hemorrhagic stroke. Risky for people who have had a previous stroke or head injury or who have uncontrolled hypertension or a bleeding disorder, aneurysm, or arteriovenous malformation. |
| urokinase (Abbokinase) | Breaks down fibrin, the main component of blood clots | Bleeding from any tissue or organ | Delivered via catheter into the arteries. Risky for people who have had a previous stroke or head injury or have uncontrolled hypertension or a bleeding disorder. |
| Last updated: | September 05, 2008 |
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Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.
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