Thrombolytic is the general term for the class of drugs used to dissolve blood clots. Clots (thrombi) can reduce or interrupt blood flow by blocking the vessel which can result in injury to the tissues that are deprived of the blood flow and oxygenation. This occurs sometimes in a "heart attack" when blood flow is restricted by a clot, and damage or death (infarction), of the tissue of the myocardium (heart muscle) results.

A common thrombolytic agent which is used for this purpose in emergency medicine measures for conditions like blood clots in the brain (cerebral thrombosis/embolus) or a coronary artery thrombosis/embolus that is causing or threatening a myocardial infarction is called TPA. TPA stands for Tissue Plasminogen Activator (also abbreviated PLAT). It acts as an enzyme to break down blood clots. Sometimes thrombolytic agents ("clot busters"/"clot busting medicines") such as Streptokinase or Urokinase are necessary to dissolve blood clots.

A related class of drugs is called anticoagulants, but rather than quickly dissolving clots like thrombolytics do, these "blood thinners," as they are sometimes called, act to prevent clot formation instead. They are used either as short term or long term medications. Examples of some of the more common anticoagulants are heparin, Coumadin, and Lovenox.

Thrombolytic drugs include:

• tissue plasminogen activator t-PA:

• alteplase (Activase)
• reteplase (Retavase)
• tenecteplase (TNKase)

• anistreplase (Eminase)
• streptokinase (Kabikinase, Streptase)
• urokinase (Abbokinase)

Among those, commonly used drugs are alteplase, reteplase and streptokinase.

Thrombolytic therapy is the use of drugs to break up or dissolve blood clots, which are the main cause of both heart attacks and stroke.

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

Thrombolytic medications are approved for the immediate treatment of strokeand heart attack. The most commonly used drug for thrombolytic therapy is tissue plasminogen activator (tPA), but other drugs can do the same thing.

According to the American Heart Association, you have a better chance of surviving and recovering from a heart attack if you receive a thrombolytic drug within 12 hours after the heart attack starts.

Ideally, you should receive thrombolytic medications within the first 90 minutes after arriving at the hospital for treatment.

FOR HEART ATTACKS

A blood clot can block the arteries to the heart. This can cause a heart attack, when part of the muscle dies due to a lack of oxygen being delivered by the blood.

Thrombolytics work by dissolving a major clot quickly. This helps restart blood flow to the heart and helps prevent damage to the heart muscle. Thrombolytics can stop a heart attack that would otherwise be deadly.

The drug restores some blood flow to the heart in most patients. However, the blood flow may not be completely normal and there may still be a small amount of muscle damaged. Additional therapy, such as cardiac catheterization or angioplasty, may be needed.

Your health care provider will base the decisions about whether to give you a thrombolytic medication for a heart attack on many factors. These factors include your history of chest pain and the results of an ECG test.

Other factors used to determine if you are a good candidate for thrombolytics include:

• Age
• Gender
• Medical history (including your history of a previous heart attack, diabetes, low blood pressure, or increased heart rate)

Generally, thrombolytics will not be given if you have:

• A recent head injury
• Bleeding problems
• Bleeding ulcers
• Pregnancy
• Surgery
• Taken blood thinning medications such as Coumadin
• Trauma
• Uncontrolled high blood pressure

FOR STROKES

Most strokes are caused when blood clots move to a blood vessel in the brain and block blood flow to that area. For such strokes (ischemic strokes), thrombolytics can be used to help dissolve the clot quickly. Giving thrombolytics within 3 hours of the first stroke symptoms can help limit stroke damage and disability.

The decision to give the drug is based upon:

• A brain CT scan to make sure there is no bleeding
• A physical exam that shows a significant stroke
• Your medical history

As in heart attacks, a clot-dissolving drug isn't usually given if you have one of the other medical problems listed above.

Thrombolytics are not given to someone who is having a hemorrhagic stroke. They could worsen the stroke by causing increased bleeding.

RISKS

There are various drugs used for thrombolytic therapy, but thrombolytics are used most often. Others drugs include:

• Lanoteplase
• Reteplase
• Staphylokinase
• Streptokinase (SK)
• Tenecteplase
• Urokinase

Hemorrhage or bleeding is the most common risk. It can be life-threatening.

Minor bleeding from the gums or nose can occur in approximately 25% of people who receive the drug. Bleeding into the brain occurs approximately 1% of the time. This risk is the same for both stroke and heart attack patients.

CONTACT A HEALTH CARE PROVIDER OR CALL 911

Heart attacks and strokes are medical emergencies. The sooner treatment with thrombolytics begins, the better the chance for a good outcome.

See also:

• Heart attack
• Stroke

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Adams HP Jr., del Zoppo G, Alberts MJ, Bhatt DL, Brass L, Furlan A, et al. Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups. Stroke. 2007;38:1655-1711.

Libby P, Bonow RO, Mann DL, Zipes, DP. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007:1241-1249.