What is thrombolytic therapy?
Thrombolytic therapy is a treatment used to break up dangerous clots inside your blood vessels. To perform this treatment, your physician injects clot-dissolving medications into a blood vessel. In some cases, the medications flow through your bloodstream to the clot. In other cases, your physician guides a long, thin tube, called a catheter, through your blood vessels to the area of the clot. Depending on the circumstances, the tip of the catheter may carry special attachments that break up clots. The catheter then delivers medications or mechanically breaks up the clot.
Thrombolytic therapy commonly is used to treat an ischemic stroke, which is another name for a clot in a blood vessel in your brain. It can also be used to treat clots in:
- A lung artery, called a pulmonary embolism
- The deep veins of your leg, called deep vein thrombosis (DVT)
- Your heart, which may cause a heart attack
- An artery elsewhere in your body, such as in an arm or leg artery
- A bypass graft or dialysis catheter that has become blocked
Your blood is normally a liquid that travels smoothly through your arteries and veins. Sometimes, however, blood components, called platelets, can form clumps and, together with other blood components, can cause the blood to gel. This process is called clotting or, more technically, coagulation. This is a normal process that protects you from excessive bleeding from even a minor injury. However, in certain circumstances blood clots can build up inside a blood vessel and block blood flow. At other times, pieces of these clots can break off, travel through your bloodstream, lodge in a blood vessel somewhere else in your body and obstruct normal blood flow. Blood clots in your heart or lungs, for example, can starve the organ and be life threatening.
Depending upon the situation, your physician may decide to provide thrombolytic therapy, also called thrombolysis, as an emergency treatment or as a scheduled procedure to dissolve the blood clots. For example, you may receive emergency thrombolysis if you are having a stroke. In some circumstances, if you have DVT or a blocked bypass graft, your physician may schedule thrombolytic therapy for you.
How do I prepare?
First your physician will ask questions about your general health, medical history, and symptoms. In addition, your physician will conduct a physical examination. Together these are known as a patient history and exam. As part of your history and exam, your physician will ask you to list any medications, including vitamins or dietary supplements, you take. Some of these substances may affect your blood's clotting ability. Your physician will also want to know when your symptoms occur and how often.
Next, your physician will order tests to make sure that you are able to receive thrombolysis safely. For example, he or she will check to see if your blood is clotting properly and that other factors, such as the mineral salts in your blood, are normal. The tests you will receive depend on which blood vessel is blocked and your medical condition. For example, your physician may order an echocardiogram test to find out whether there is a blood clot in your heart or an electrocardiogram (ECG) to evaluate your heart rhythm.
Your physician will give you the necessary instructions you need to follow before the thrombolysis procedure, such as fasting. Usually, your physician will ask you not to eat or drink anything 12 hours before your procedure. Your physician will also discuss with you whether to reduce or stop any medications that might increase your risk of bleeding or other complications.
You will usually undergo a test called angiography either before or as part of thrombolytic therapy. Angiography creates a picture of your blood vessels (called an angiogram), and uses a dye, called contrast, which is eventually flushed out through your kidneys. If you have kidney trouble, or if you have had a test that uses contrast before and had an allergic reaction to the contrast, you should tell your vascular surgeon. He or she may prescribe medications designed to minimize the chance of problems with the contrast material.
Am I a candidate for thrombolytic therapy?
You may be a candidate for thrombolytic therapy if you have symptoms of a stroke, heart attack, pulmonary embolism, DVT, or a clot in an artery or bypass graft in a limb. These symptoms may include:
- Chest pain
- Numbness or tingling on one side of the body
- Blurred vision in one eye
- Slurred speech
- Sudden weakness
- Severe swelling of an arm or leg
- Pain, numbness or coldness in a limb
If you have a life-threatening clot, your physician will attempt to establish thrombolytic therapy as soon as possible after symptoms begin, preferably within 1 to 2 hours.
If you have severe high blood pressure, active bleeding or severe blood loss, a stroke from bleeding in the brain (called hemorrhagic stroke), severe liver disease, or have recently had surgery, you probably are not a good candidate for thrombolytic therapy because of the increased risk of bleeding associated with these conditions.
Am I at risk for complications during thrombolytic therapy?
If you have diabetes or kidney disease, you may have a higher risk of complications from the contrast agents used in the angiogram. If you have kidney disease, sometimes your physician can treat you with medications or fluids before you receive contrast, to protect your kidneys and minimize the risk.
People with blood clotting disorders also may have a higher risk of complications from thrombolysis. Other factors that may increase the risk for complications include:
- History of internal bleeding
- Endocarditis, an infection in the lining of the heart
- Advanced age
- Recent surgery or injury
- Poorly controlled hypertension
- Diabetic retinopathy, a problem in the eyes that results from diabetes
What happens during thrombolytic therapy?
In some hospitals, physicians perform thrombolytic therapy in the intensive care unit, but in others thrombolysis may be performed in nursing units familiar with the treatment and potential complications. In either circumstance, your physicians and nurses will carefully watch your vital signs and be prepared for an emergency during the procedure, such as bleeding. Initially, you will lie on an x-ray table, and machines will monitor your vital signs.
Thrombolytic drugs can be delivered in two ways: through a short catheter inserted in a vein (called an intravenous, or IV, catheter), or through a long catheter that is guided to the clot through your arteries or veins. In emergencies, vascular surgeons often choose the IV method because it is quick and safe to perform outside of a hospital. If your physician chooses to guide the catheter directly to the clot, the end of the catheter may be placed in the vessels leading to your brain, lung, heart, arm, or leg depending upon the location of the clot.
To deliver the thrombolytic therapy, your physician will make a small puncture over an artery or vein in your groin, your wrist, or your elbow. This place is called the access site. Before inserting the catheter through this puncture, he or she will clean your skin and shave any hair. This reduces your risk of infection. Your physician then will numb your skin with a local anesthetic and then sometimes makes a small cut or puncture to reach the blood vessel below. Although you may be given some mild sedation, you will usually stay awake during the procedure.
Next, your physician will usually inject contrast through the catheter to map your blood vessels with angiography and to locate the clot. You may feel a warm sensation during the injection, which is normal. As the contrast flows through your blood vessels, x-rays are taken. The x-rays do not pass through the contrast, so pictures of your blood vessels appear on a screen. An indication of the clot location will appear as well.
Once your physician locates the clot, depending on the particular circumstances, he or she may inject the thrombolytic drugs through an IV catheter. More commonly, your vascular surgeon will guide a longer catheter through your blood vessels to the vicinity of the clot and then inject the drugs near or into it. Because you have no nerve endings in your blood vessels, you will not feel the catheters as they move through your body.
Currently, the most common thrombolytic agents (“clot-busting" drugs) are:
- Tissue plasminogen activator (t-PA)
- Recombinant, or genetically engineered, t-PA (a newer version of t-PA) and TNK (Tenecteplase)
Your physician will periodically monitor the x-ray screen to see the clot breaking up. However, depending on the size and location of the clot, the drugs your physician chooses, and other factors, this process can take several hours. Sometimes, if you have a severe blockage, the treatment could last for several days. Once the clot has been dissolved or if it cannot be dissolved further, your physician will stop the medication. When the tests used to monitor your blood's coagulation ability are in a satisfactory range, your physician will then remove the IV or catheter, and press on the access site for 10 to 20 minutes to stop any bleeding. During the process, and for several hours afterwards, your physician will ask you to remain still to minimize the risk of bleeding from the access site.
The technique for mechanical thrombectomy is similar, except that small devices are attached to the catheter tip to remove the clot or even break it up physically. These devices include a suction cup, a rotating device, a high-speed fluid jet, or special ultrasound devices. Mechanical thrombectomy can work faster than thrombolytic drugs in some cases, and in favorable circumstances the procedure may take as little as 30 minutes. In some situations, both mechanical and pharmacologic thrombolysis will be performed. Your physician will advise you if you are a good candidate for mechanical thrombectomy.
What can I expect after thrombolytic therapy?
Usually, you will stay in bed as you recover from thrombolytic therapy. During this time, your physician and the hospital staff closely watch you for any complications. You may receive fluids, antibiotics, or painkillers. If your physician inserted the catheter through an artery in your arm or leg, you may have to hold the limb straight for several hours. Once any bleeding from the access site stops, and your vital signs are normal, you may be discharged. Often, however, you will require further hospitalization for treatment of the underlying reason for the clot, or for adjustment of anticoagulation doses if needed to prevent clots from reforming.
If you notice any unusual symptoms after or during your procedure, you should tell your physician immediately. These symptoms may include:
- Arm or leg pain that lingers or gets worse
- A fever
- Shortness of breath
- An arm or a leg that turns blue, develops swelling, or feels cold
- Problems around your access site, such as bleeding, swelling, pain, or numbness
Before your discharge, your physician will give you instructions about everyday tasks to follow after you return home. For example, you should not lift more than about 10 pounds for the first few days after your procedure. You should drink plenty of water for 2 days to help flush the contrast dye out of your body. You can usually shower 24 hours after your procedure, but you should avoid baths for a few days.
During your recovery, you may experience nausea, vomiting, or coughing. You should tell your physician if any nausea, back pain or lightheadedness lingers, because these symptoms could mean you have internal bleeding.
If you received thrombolytic therapy in an emergency, you may receive additional care for your condition. For example, if you had a stroke, your physician may prescribe medications, a special diet, or physical therapy. If you had a heart attack, your physician may need to examine your heart to see if any other arteries are blocked. If you had a blocked bypass graft, you may need further treatment or anticoagulation to keep the bypass open.
Are there any complications?
Complications are not unusual with thrombolytic therapy, which is why it should be carried out under close supervision. However, your physician can manage most of them, including:
- Bleeding in the access site or elsewhere
- Low blood pressure
- Allergy to thrombolytic drugs
Bleeding in the brain leading to stroke can also occur, but it is rare and affects fewer than 1 in 100 patients.
Thrombolytic therapy is not always successful. In up to 25 percent of patients, the treatment is unable to break up the clot. This is especially true if the clot has been established for a long time. In another 12 out of every 100 patients, the clot or blockage will re-form in the blood vessel, especially if an underlying reason for the clot to form in the first place is not found and treated.
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Revised September 24, 2009