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
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
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.
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
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
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
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
- 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
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.