| Thrombolysis
What is Radiological Thrombolysis? Back to Top
Thrombolysis
is the treatment to break up abnormal blood clots that are restricting
blood flow. Thrombolytic therapy dissolves these blood clots using
various medications administered directly into the clot through a
catheter. Mechanical thrombolysis is the disruption of a blood clot
using one of several mechanical devices. An interventional radiologist
can use either or both of these methods to dissolve and remove blood
clots. The procedure is performed by an interventional radiologist, a
physician specially trained to perform thrombolysis and similar
procedures. Radiological thrombolysis can greatly improve blood flow
and reduce or eliminate the related symptoms and effects without the
need for more invasive surgery.
What are some common uses of the procedure? Back to Top
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.
Radiological 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; this is known as 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? Back to Top
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 radiological thrombolysis 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 before the procedure
begins.
What does the equipment look like? Back to Top
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? Back to Top
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? Back to Top
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, 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 interventional 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 to 48 hours
for the clot to dissolve. It is common to be kept in an ICU or other
monitored unit so that the nursing staff can watch you carefully while
you are undergoing treatment. During the time that you are receiving
thrombolytic medication, the interventional radiologist monitors the
progress of the treatment using additional imaging scans.
What will I experience during the procedure? Back to Top
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? Back to Top
The
interventional radiologist can 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? Back to Top
Benefits
- 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.
Risks
- 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.
- In
some cases the material that is blocking your vessel may move to
another part of the vascular system. Usually this can be treated with
further thrombolysis but sometimes may require surgery.
- 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 Radiological Thrombolysis? Back to Top
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. Back to Top |
