Tpa Clot Dissolver

A stroke occurs when the blood supply to brain tissue is blocked by a blood clot (ischemic stroke), or when a blood vessel in the brain ruptures (hemorrhagic stroke), causing brain cells to die and leading to functional impairments. Stroke is a leading cause of death and disability both globally and in the U.S., where approximately 800,000 people experience a stroke each year1. This study will test the effectiveness of low-dose recombinant tissue plasminogen activator (rtPA, or alteplase) in dissolving blood clots in deep leg veins. Alteplase is used to clear blood clots in coronary arteries in patients having heart attacks. Alteplase is a thrombolytic (THROM-bo-LIT-ik) drug, sometimes called a 'clot-busting' drug. It helps your body produce a substance that dissolves unwanted blood clots. Alteplase is used to treat a stroke caused by a blood clot or other obstruction in a blood vessel. This “clot-buster” drug has been used in people with central venous access devices to help restore catheter function and in cases of myocardial infarction within 6 hours of clinical signs. The reconstituted TPA is good for 8 hours, and has been frozen and then used for up to 6 months duration. UPA (urokinase-type plasminogen activator) and tPA (tissue-type plasminogen activator), the drug that is the only approved treatment for acute stroke, have similar names, because they both act biochemically to activate plasmin, which directly dissolves blood clots. “We are finding that uPA and tPA do very different things in the brain.

An experimental drug now given to heart attack victims may also be an effective treatment for patients with blood clots in their lungs, Harvard researchers will report today.

Led by Dr. Samuel Z. Goldhaber '72, an assistant professor of medicine, a group of doctors at Brigham and Women's Hospital gave a drug called Tissue Plasminogen Activator (TPA) to 40 patients with blood clots in their lungs, and it quickly broke up the clots in 37 of them.

90 Percent Success

'It exceeded our best hopes,' Goldhaber said. 'Over 90 percent of the clots disolved within six hours.'

Although TPA has been tested in several thousand heart attack victims around the world, this study represents the first time it has been given to patients with lung clots, called pulmonary embolisms.

Blood clots can cause a variety of ailments, ranging from chronic shortness of breath to heart attacks.

'We were initially afraid that this dose of TPA wouldn't do the job, because a clot that goes to the pulmonary arteries is much bigger [than one in the arteries of the heart,]' Goldhaber said.

Although it worked effectively on most lung-clot victims, TPA also caused serious internal bleeding in six percent of the patients. Goldhaber said that more, larger-scale trials would be necessary before the Food and Drug Administration would consider approving the drug for widespread use.

Goldhaber's complete study appears in today's issue of the British journal Lancet.

More than 50,000 Americans die each year from pulmonary embolisms, and another 300,000 are hospitalized annually, the researchers estimate.

Blood clots frequently form in an artery in the leg or pelvis, travel through the blood stream and get stuck in the arteries which carry blood from the heart to the lungs.

When treating victims of pulmonary embolisms, doctors usually wait for the blood clots to dissolve on their own, although they do prescribe blood-thinning drugs to prevent more clots from forming.

Another clot-dissolving drug, Urokinase, was approved by the Food and Drug Administration for experimental use in pulmonary embolism victims in 1977, but TPA seems to work more effectively, Goldhaber said.

When you are having a stroke, you need to go to the ER ASAP, undergo a CT STAT and receive tPA through an IV if necessary. In other words, upon recognizing the symptoms of a stroke, you should proceed to the nearest emergency room (ER) as soon as possible (ASAP). Upon arrival, you would undergo a computed tomography (CT) scan immediately (STAT) to determine the cause of the stroke. If a blood clot is detected during the scan, you may receive tissue plasminogen activator (tPA) intravenously (IV) to help break up the blood clot.

More than 80 percent of strokes are caused by a blood clot that moves into a vessel and blocks blood flow. These ischemic strokes typically are treated with tPA, a clot-busting drug that helps dissolve the blood clot and restore blood flow to the brain. Strokes also may be caused by the rupture of a weakened blood vessel, resulting in blood leaking into the brain. These hemorrhagic strokes should not be treated with tPA because the medication could cause increased bleeding.

The key to successful treatment for ischemic strokes is rapid treatment. That is because when tPA is administered within three hours of the onset of symptoms, it can help reduce disability and limit damage caused by lack of blood flow to the brain. Although tPA usually is given through an IV, it also can be delivered through a long catheter that is guided through blood vessels directly to the blockage. This alternative may benefit patients when treatment cannot begin within three hours after stroke symptoms started or when initial tPA treatment has not been sufficient to dissolve the blood clot. The local administration of tPA can occur up to six hours after the onset of stroke symptoms.

Tpa Blood Clot Dissolver

The decision to use tPA or other clot-busting drugs, also called thrombolytics, is based on numerous factors, including age, gender and medical history.

In general, tPA is not recommended for patients who are pregnant or have:

A history of bleeding problems.
Uncontrolled high blood pressure or endocarditis
(infection of the lining of the heart).
Had recent surgery or injury.
Diabetic retinopathy (eye problems due to diabetes).

In addition to treating ischemic strokes, thrombolytic therapy using tPA also may be used to treat clots in the lungs, deep veins in the legs, heart, or arteries elsewhere in the body. However, clots may reform in blood vessels, especially if the underlying cause for the blockages is not properly diagnosed and treated. Following treatment with tPA, patients are advised not to take anticoagulants or antiplatelets, such as aspirin, which could interfere with normal clotting.