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Thrombolytic therapy (tissue plasminogen activator - tPA)

Alternative names

TPA; Alteplase; Reteplase; Tenecteplase; Activase thrombolytic agent; Clot-dissolving agents; Reperfusion therapy


Thrombolytic therapy is a drug that break ups or dissolves blood clots, which are the main cause of both heart attacks and stroke.


Since 1996, tPA has been approved by the Food and Drug Administration (FDA) for the treatment of stroke and heart attack . According to the American Heart Association (AHA), if tPA is given within the first 3 hours of a stroke, it may reduce permanent disability. If given within 12 hours of the onset of a heart attack, the person has a better chance for survival and recovery.

There are various drugs that dissolve clots, but tPA is currently used most often. Others include Streptokinase (SK), Reteplase, Tenecteplase, Urokinase, Lanoteplase, and Staphylokinase.

According to the American College of Cardiology (ACC), each year 800,000 persons in the United States have acute heart attacks and 213,000 die. Those who die from heart attacks generally die within 1 hour from the initial onset of symptoms and sometimes before they get to the hospital.

Guidelines are used to determine if someone is a good candidate for using tPA. Many national groups are working together to decrease the time it takes to get people having a heart attack to facilities where tPA can be given. The sooner thrombolytic therapy is given, the better the outcome. The window of opportunity is a very short amount of time.

For a person having an acute heart attack, tPA works by dissolving a major clot quickly. The clot is most likely blocking one of the coronary arteries that normally allows blood and oxygen get to the heart muscle.

By dissolving the clot, the blood is able to start flowing again to that area of the heart. If the blood flow to the heart is started again rapidly, it may prevent long-term damage to the heart muscle and may even stop an event that could have been fatal.

The drug is successful in restoring some blood flow to the heart muscle in approximately 75% of patients, but the resultant blood flow may not be entirely normal. Further therapy, such as cardiac catheterization, may be needed.

Physicians base their decisions about whether to give tPA for a heart attack on many factors, including a history of chest pain and the results of an ECG test .

Other factors used to determine if someone is a good candidate for tPA include age, medical history, gender, history of previous heart attack, history of diabetes, history of low blood pressure, or increased heart rate, and if the person is elderly (older than 70 years).

Generally, tPA will not given if the person has had a recent head injury, trauma, surgery, bleeding problems, uncontrolled high blood pressure, bleeding ulcers, or pregnancy.

Close to 80% of all strokes are ischemic strokes, caused when blood clots form in one place in the body and travel to a smaller blood vessel in the brain, blocking the blood flow to that area.

For strokes of this nature, tPA can help dissolve the clot quickly. Often, tPA can limit the amount of permanent disability that can result from an ischemic stroke, especially if given within 3 hours of the initial symptoms of the stroke.

The decision to administer the drug is based upon the history, physical exam consistent with a significant stroke, and a brain CT scan to exclude bleeding.

If someone is having a hemorrhagic stroke or a stroke caused by bleeding in the brain, tPA is not given because this could worsen the stroke by causing increased bleeding.

Ischemic strokes often occur when a person is at rest or not under physical duress. Hemorrhagic strokes often occur during some sort of physical exertion. In some cases, the diagnosis of the actual type of stroke may be difficult and the risk of bleeding from tPA is a concern. Generally, the benefits of receiving it outweigh the risks if given in a timely manner.

Hemorrhage or bleeding is the most common risk associated with the administration of tPA therapy. Bleeding which is mostly minor, such as gum or nose bleeding, can occur in approximately 25% of people, while bleeding into the brain occurs approximately 1% of the time. This is true for both stroke and heart attack patients.

The key for people suffering from a heart attack or a stroke is recognizing that both conditions are medical emergencies. The sooner transportation and treatment with tPA takes place for acceptable candidates, the better the chance that person has for a good outcome.

Please refer to the stroke and heart attack articles for specific symptoms for both conditions. If you suspect you or someone you know is suffering from symptoms of a heart attack or stroke, you should seek help immediately!

Update Date: 7/28/2002

Steven Kang, M.D., Division of Cardiology, Harbor-UCLA Medical Center, Torrance, CA. Review provided by VeriMed Healthcare Network.

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT