Thrombolysis

Thrombolysis is a life-saving treatment that dissolves dangerous blood clots blocking your blood vessels. Time is critical—when you’re having a heart attack or stroke, every minute counts, and this therapy can mean the difference between recovery and permanent damage.

Table of contents

• What is Thrombolysis?
• Conditions Treated with Thrombolysis
• Types of Thrombolytic Therapy
• Medications Used
• When Treatment Should Begin
• How the Procedure Works
• Risks and Contraindications
• Effectiveness and Outcomes

thrombolytic therapy, fibrinolytic therapy, clot-busting therapy

What is Thrombolysis?

Thrombolysis, also known as thrombolytic therapy or fibrinolytic therapy, is a treatment that uses medications to break up or dissolve blood clots that have formed in your blood vessels^[1]. These clots can block the flow of blood and oxygen to vital organs like your heart, brain, or lungs, causing serious damage or even death.

The main goal of thrombolysis is to restore blood flow quickly to prevent damage to your body’s organs and tissues^[2]. Blood clots normally form to stop bleeding when you’re injured, but sometimes they develop abnormally inside blood vessels where they shouldn’t be. When this happens, they can cut off the blood supply to important parts of your body.

Healthcare providers deliver thrombolytic medications either through an intravenous (IV) line in your arm or through a thin tube called a catheter that is guided directly to the location of the clot^[3]. The sooner treatment begins, the better the chances of limiting damage and improving recovery.

Conditions Treated with Thrombolysis

Thrombolytic therapy is used to treat several serious medical emergencies and conditions where blood clots pose immediate danger^[1]:

• Heart attack (myocardial infarction): When a blood clot blocks an artery feeding the heart, part of the heart muscle can die from lack of oxygen^[7].
• Ischemic stroke: This type of stroke happens when blood clots block vessels in the brain, preventing oxygen from reaching brain tissue^[5].
• Pulmonary embolism: A blood clot that travels to the lungs and blocks blood flow, which can be life-threatening^[3].
• Deep vein thrombosis (DVT): Blood clots that form in the deep veins of the legs, which can break off and travel to the lungs^[1].
• Acute peripheral arterial occlusion: Sudden blockage of blood flow to the arms or legs^[3].
• Blockages in bypass grafts or dialysis catheters: When medical devices or surgical grafts become blocked by clots^[1].
• Intracardiac thrombus: Blood clots that form inside the chambers of the heart^[3].

Types of Thrombolytic Therapy

Healthcare providers use three main approaches to deliver thrombolytic therapy^[2]:

Systemic thrombolysis involves giving the medication through an IV line, usually in your arm. The drug travels through your bloodstream until it reaches the clot. This method is commonly used as an emergency procedure for heart attacks, strokes, and pulmonary embolism^[11]. Because the medication circulates throughout your entire body, it may be diluted before reaching the clot, sometimes requiring higher doses.

Catheter-directed thrombolysis uses a long, thin tube that doctors guide through your blood vessels directly to the location of the clot^[1]. This method delivers the medication right where it’s needed and is often used as a scheduled procedure to treat deep vein thrombosis and peripheral arterial disease. Doctors use imaging technology to watch the clot dissolve in real time.

Mechanical thrombectomy involves using a catheter with a special device at the tip—such as a tiny suction cup, rotating device, high-speed fluid jet, or ultrasound device—to physically break up or remove the clot^[1]. This technique is sometimes used along with catheter-directed thrombolysis.

Medications Used

Several different medications can dissolve blood clots. These drugs are called thrombolytic agents or plasminogen activators because they work by activating a substance in your blood called plasmin, which breaks down the proteins that form clots^[3].

The most commonly used clot-busting medications include^[1]:

• Alteplase (tissue plasminogen activator or t-PA): This is often the first choice for treating strokes, pulmonary embolisms, and heart attacks. It rarely causes allergic reactions^[13].
• Reteplase: This medication works faster than some other thrombolytics^[13].
• Tenecteplase: This drug works efficiently and is frequently chosen by doctors in North America and Europe. It also has a lower risk of bleeding^[13].
• Streptokinase: The most widely used medication globally due to its lower cost and good effectiveness, though it’s used less often in the United States^[3].
• Urokinase: Often chosen for treating clots in the legs and blocked catheters^[13].
• Anistreplase: This medication can work throughout your whole body^[1].

When Treatment Should Begin

Timing is absolutely critical for thrombolytic therapy. The sooner treatment starts, the better your chances of recovery and the less damage your organs will suffer.

For heart attacks, outcomes are significantly better if you receive thrombolytic medication within 12 hours after symptoms begin, but ideally within the first hour^[7]. Healthcare providers aim to start treatment within 30 minutes of your arrival at the hospital^[2].

For strokes, giving thrombolytics within 3 hours of the first symptoms can help limit damage and disability^[7]. Some patients may still benefit from treatment up to 6 hours after symptom onset, depending on their individual situation^[5].

For pulmonary embolism and other conditions, treatment should be initiated as soon as possible—ideally within one to two hours after symptoms begin, once a diagnosis has been made^[1]. In some cases, paramedics may even start thrombolytic therapy before you reach the hospital^[13].

How the Procedure Works

The exact steps of thrombolytic therapy depend on whether doctors are using systemic or catheter-directed treatment.

For systemic thrombolysis, your healthcare team will usually treat you in an intensive care unit where they can closely monitor your heart and lung function^[2]. They will give you a sedative to help you relax and use a local anesthetic to numb the area where they insert the IV line. The medication then travels through your bloodstream to reach the clot.

For catheter-directed thrombolysis, doctors create a tiny puncture in a blood vessel and inject contrast dye to find the exact location of your clot^[12]. You may feel a warm sensation when the dye is injected. Next, they guide a catheter up to the blood clot and administer the thrombolytic medication directly at that spot.

Throughout the procedure, doctors use imaging technology to watch whether the clot is dissolving^[1]. If the clot is relatively small, the process may take several hours. However, treatment for a severe blockage may be necessary for several days. The treatment time varies from about 60 minutes for a typical heart attack to up to 48 hours for conditions like deep vein thrombosis^[11].

Risks and Contraindications

While thrombolysis can be lifesaving, it’s not safe for everyone. The most serious risk is bleeding, which can be life-threatening^[7].

Approximately 5% of treated patients will have a major bleed, and bleeding in the brain (intracranial hemorrhage) occurs in about 1% of cases^[11]. Minor bleeding from the gums or nose happens in about 25% of people who receive the medication^[7]. Other possible bleeding sites include the urine, nose, digestive tract, and in women, unusually heavy vaginal bleeding.

Additional risks include^[1]:

• Bruising or bleeding at the site where the catheter or IV was inserted
• Damage to blood vessels
• Small pieces of the clot breaking off and traveling to other parts of your body (embolization)
• Kidney damage, particularly in patients with diabetes or pre-existing kidney disease
• Infection (less than one in 1,000 cases)
• Allergic reaction to contrast dye used for imaging

Healthcare providers will not recommend thrombolytic therapy if you have conditions that increase your risk of bleeding, including^[2]:

• Active bleeding or recent brain hemorrhage
• Recent brain or spine surgery
• Recent traumatic brain injury or head injury
• Severe high blood pressure (hypertension)
• Severe kidney disease
• Recent surgery (within the past few weeks)
• Bleeding problems or bleeding ulcers
• History of taking blood-thinning medications such as warfarin
• Recent trauma

Pregnant women and elderly people also have an increased risk of complications^[2]. Your doctor will carefully consider your medical history, age, sex, and other factors to determine if you’re a good candidate for thrombolytics^[7].

Effectiveness and Outcomes

Thrombolysis can safely and effectively improve blood flow and relieve or eliminate symptoms in many patients without the need for more invasive surgery^[1]. For heart attacks, the medication restores some blood flow to the heart in most people, though the flow may not be completely normal and there may still be some muscle damage^[7]. Further treatment, such as cardiac catheterization with angioplasty and stenting, may be needed.

Large research studies have shown that mortality can be reduced when thrombolysis is used to treat heart attacks^[5]. For strokes, thrombolysis reduces major disability or death when given within the appropriate time window and when there are no contraindications to treatment^[5].

Thrombolytic therapy usually successfully treats blood clots, but you may also need other procedures or surgery to treat the underlying cause of the clot formation^[2]. The success of the treatment depends heavily on how quickly it is started—the sooner you receive thrombolytics after symptoms begin, the better your chance for a good outcome^[7].

If thrombolytics are considered too dangerous for your situation, other possible treatments for clots include removal of the clot through a procedure called thrombectomy or a procedure to open narrowed or blocked blood vessels^[7].