Interventional Radiology


Catheter-directed thrombolysis usually is performed in a hospital radiology suite by an interventional radiologist. The physician inserts the catheter into a vein in the leg and threads it to the site of the clot. With his special training as a radiologist, the doctor is able to expertly guide and watch the progress of the procedure on an X-ray video monitor. When the catheter tip is in the clot, the clot-dissolving drug is sent (infused) through the catheter tube. Some types of clot may also need dissolution with special mechanical catheters that literally “vacuum” the clot out of the vessel.  It may take 24 to 48 hours for the clot to completely dissolve. The interventional radiologist can “see” and monitor the treatment using special X-rays, called venograms, and ultrasound scans. With X-ray and ultrasound pictures, the physician also can see if – after the clot dissolves – the vein wall is narrowed or damaged, which can lead to more clots in the future. 

What Are Some Common Uses Of Thrombolysis?

Whenever blood does not flow smoothly, clots can develop, slowing or blocking the blood supply to an organ or extremity. The blockage, known as a thrombosis, may cause no noticeable symptoms, or it may cause pain, numbness, coldness, tingling or swelling in an arm or leg, or poor function in an affected organ. Tissue deprived of adequate circulation can be seriously damaged.

Thrombolysis can help to treat clots in arteries and veins resulting from various causes:

  • Recent surgery, infection, immobility, and disorders that affect vascular health, such as diabetes, can slow circulation and allow clots to form.
  • Fatty cholesterol deposits may form in the walls of an artery, causing a narrowing that restricts blood flow and forms clots.
  • In the veins, a series of valves work like gates to stop backflow and move the blood toward the heart. Vascular disease can damage these valves, slowing the normal flow of blood and creating pockets of backflow (called turgidity), where clots can develop. A deep vein thrombosis is a blood clot that forms in a main vein that returns blood flow from the extremities to the heart and lungs and may grow big enough to completely block the vein. If part of the clot breaks off and travels to the lungs, the risk to health can be serious.
  • Slowed circulation caused by heart disease can allow a blood clot to form in one of the heart's chambers and then travel through the bloodstream, lodging in either an organ or an artery and cutting off the blood supply from that point, causing an embolism.
  • Clots restricting blood flow to the heart may trigger a heart attack; in the brain, clots may cause stroke.

How Should I Prepare For The Procedure?

Since your doctors already know that there is a problem with your circulation, you may have already experienced an arteriogram or a venogram, a special x-ray examination of the blood vessels. If so, you will find preparation for  thrombolysis is very similar to your earlier experience.

Several days before the procedure, you will receive instructions from office staff of the physician who will be performing it—an interventional radiologist. You will have blood drawn at the hospital or at a local clinic to learn how well your kidneys are functioning and whether your blood clots normally. Staff also will advise you if there is to be a change in your medication schedule, especially for medications that thin the blood (anticoagulants). You will be admitted to the hospital the day before the procedure or the morning of the procedure and will be examined by the radiologist just before it begins.

What Does The Equipment Look Like?

The x-ray equipment and catheters are the same as those used for catheter angiography. The angiographic catheter is a long plastic tube about as thick as a strand of spaghetti. The x-ray equipment is mounted on a C-shaped gantry with the x-ray tube itself beneath the table on which the patient lies. Over the patient is an image intensifier, a device that receives the x-ray signals after they pass through the patient, amplifies them, and sends them to a TV monitor.

How Does The Procedure Work?

When a clot forms, blood flow is obstructed and tissues in the affected area cannot receive the necessary oxygen and nutrients from the arteries, and/or cannot remove excess fluids and by-products through the veins. Once a clot starts to form in a blood vessel, it may continue to grow larger until the entire vessel is blocked, completely depriving the area of blood circulation. Untreated, severe blockages can damage or even kill affected tissue, causing the loss of the organ or extremity, with potentially life-threatening consequences.

Reducing or eliminating the clot helps to re-establish blood flow and prevent further damage to the affected tissues. Once the clot has been removed, any underlying conditions that might cause future clot formation can be seen and treated appropriately.

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How Is The Procedure Performed?

A sedative is injected through an intravenous (IV) line to relax you, though at times a general anesthetic is given instead. The interventional radiologist will then find an appropriate blood vessel, usually in the groin, arm or neck, and numb the area with a local anesthetic. A thin catheter is passed through a very small incision into a blood vessel and, guided by x-rays, the catheter is maneuvered to the area of poor circulation. Contrast material then is injected and a series of x-rays are taken to pinpoint the location of the clot. The radiologist will review the images to determine whether the clot would be best treated by a clot-dissolving medication, by breaking it up with a mechanical device, or both.

The catheter is advanced through the blood vessels of the body to the vessel that has the clot. If the clot will be treated with medication, the catheter is left in place, connected to a special machine that delivers the medication at a precise rate. The clot-dissolving medications are delivered through the catheter over several hours to several days. You will stay in the hospital for the duration of the medication treatment. It usually takes 24 - 48 hours for the clot to dissolve. During that time, the interventional radiologist monitors the progress of the treatment using additional imaging scans. Some cases allow usage of a mechanical thrombectomy device which may shorten procedure times.

What Will I Experience During The Procedure?

The intravenous (IV) sedative will make you feel relaxed and sleepy and you may nod off for brief periods, but generally will remain awake throughout the procedure. You may feel slight pressure when the catheter is inserted, but no serious discomfort. As the contrast material passes through your body, you may get a warm feeling. However, this soon passes.

To avoid disrupting the catheter's precise placement, your movement will be restricted during the time the clot-dissolving medication is being administered. When the clot is removed, or when no further improvement can be achieved, the medication will be stopped and the catheter removed. You will be required to lie quietly for some time afterward, usually with pressure applied to the entry site to prevent bleeding.

Many patients experience some side effects after thrombolysis. Pain is the most common, and can readily be controlled by oral or intravenous medication. Most patients can resume their normal activities within a week or two. You may or may not remember some things about the procedure.

Who Interprets The Results And How Do I Get Them?

Your VIA interventional radiologist will advise you as to whether thrombolysis was a technical success when the procedure is completed. You will be advised as to whether additional treatment is required for the original condition that caused the clot, or to repair any tissues damaged while your circulation was impaired.

What Are The Benefits Vs. Risks?


  • Thrombolysis is a safe, highly effective way of re-establishing circulation blocked by a clot.
  • Thrombolysis is less invasive than conventional open surgery to remove clots, and the hospital stay is relatively brief. Blood loss is less than with traditional surgical treatment, and there is no obvious surgical incision.


  • There is a risk of infection after thrombolysis, even if an antibiotic has been given.
  • Whenever anticoagulant or thrombolytic agents are used, there is a risk that bleeding will occur elsewhere in the body. There is a rare (1%) risk of stroke/intracranial bleeding, which can be fatal.
  • Because angiography is part of the procedure, there is a risk of an allergic reaction to contrast material.
  • Because angiography is part of the procedure, there is a risk of kidney damage in patients with diabetes or other pre-existing kidney disease.

What Are The Limitations Of Thrombolysis?

Technically successful thrombolysis requires that the catheter be placed in a stable position near the clot. This means that the catheter tip is situated so that the clot-dissolving agent can reach the site of the obstruction. In a small percentage of cases, the procedure is not technically possible. It is important to understand that clot removal alone cannot repair tissue already damaged by lack of circulation. Further treatment may be required, both for the underlying condition that caused the clot and for any damage to affected organs or other tissues.


To get more information or to schedule a procedure, please call Vascular & Interventional Associates 859-341-4VIA (4842).