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					Angioplasty and Vascular Stenting

What are Angioplasty and Vascular Stenting?

Angioplasty, also called balloon angioplasty, and vascular stenting are minimally invasive
procedures performed by an interventional radiologist to improve blood flow in the body's
arteries.

In the angioplasty procedure, the physician threads a balloon-tipped catheter—a thin, plastic
tube—to the site of a narrow or blocked artery and then inflates the balloon to open the
vessel. The balloon is then deflated and removed from the artery. Vascular stenting, which is
often performed at the same time as an angioplasty, involves the placement of a small wire
mesh tube called a stent in the newly opened artery. This may be necessary after some
angioplasty procedures if the artery is narrowed or completely blocked. The stent is a
permanent device that is left in the artery and may be needed to help the artery heal in an
open position after the angioplasty.

What are some common uses of the procedures?

Narrowing or blockage in the arteries is most often caused by atherosclerosis, also called
hardening of the arteries. Although it is commonly thought of as a heart disease,
atherosclerosis can affect arteries anywhere in the body, including the legs and the brain. It is
a gradual process in which cholesterol and other fatty deposits—called plaques—build up on
the artery walls. These plaques act as barriers that limit blood flow through the arteries to
tissues and organs. Other barriers to adequate blood flow include clots or plaques that break
away from the blood vessel wall and become lodged in an artery.

When a blood clot, plaque or scar tissue cause an artery to become narrow or completely
blocked, blood circulation is limited and the organs and tissues supplied by that artery do not
receive enough oxygen.

Angioplasty and vascular stenting are commonly used to treat conditions that result when
arteries throughout the body become narrowed or blocked, including:

        Peripheral vascular disease (PVD)/peripheral artery disease (PAD) (narrowing of the
        arteries in the legs or arms).
        Renal vascular hypertension (high blood pressure caused by narrowing of the kidney
        arteries).
        Hemodialysis access maintenance.
        Carotid artery disease (narrowing of the neck arteries supplying blood to the brain).
        Coronary artery disease (narrowing of the heart arteries).

Peripheral vascular disease (PVD), also called peripheral artery disease (PAD), is a
condition in which there is insufficient blood flow through the arteries to the arms or legs,
causing pain, cramping or heaviness in the muscles (called intermittent claudication). Causes
of PVD and PAD include atherosclerosis, scar tissue and blood clots. In patients with PVC
or PAD, angioplasty may be used to open up a blocked artery in the pelvis, leg or arm. A
common site is the iliac arteries of the pelvis.

Renal vascular hypertension is a condition in which one or both of the arteries that supply
blood to the kidneys narrow significantly due to atherosclerosis. This reduced blood flow
through the renal artery causes the kidney to release increased amounts of the hormone
renin, which is responsible for regulating blood pressure. The increase in renin begins a
series of chemical events in the body that result in hypertension, also called high blood
pressure. Angioplasty and stenting are used to improve blood flow and reduce blood
pressure.

Hemodialysis access maintenance. Patients with kidney failure must have regular
hemodialysis treatments to prevent waste products from building up in the blood. Some of
these patients have a graft (a synthetic material) constructed between an artery and vein in
the arm so that blood can easily be withdrawn and replaced during dialysis. On average,
these grafts stay open for about one year. Repeated angioplasty can help a graft stay open for
as long as five years. Many patients have an arteriovenous fistula, a connection made
between the artery and vein that can be used for dialysis. In some cases angioplasty may be
used to help improve these connections.

Carotid artery disease is a condition in which there is decreased blood flow in one or both
of the carotid arteries, large arteries in the neck that are the major routes of blood and
oxygen to the brain. Not enough blood flow to the brain can lead to a stroke. A stroke can
also be the result of a piece of plaque breaking off or a blood clot forming, blocking a
narrowed or smaller artery of the brain. Interventional radiologists are currently studying the
effectiveness and safety of angioplasty and stent placement in the carotid arteries. The
procedure would be helpful to patients who are not good candidates for surgery.

Coronary artery disease (CAD), also called coronary heart disease (CHD), results when
the coronary arteries—the blood vessels that carry blood and oxygen to the heart muscle—
become clogged with plaque due to atherosclerosis. Clogged arteries that do not deliver
enough blood and oxygen to the heart can cause chest pain, called angina. A blood clot that
forms, suddenly cutting off blood flow in the artery, can cause a heart attack. Angioplasty
and vascular stenting are often used to open blocked coronary arteries.

How should I prepare for the procedure?

Prior to the procedure, you may have several tests performed, such as x-rays, an
electrocardiogram (ECG) and blood tests. You should tell your doctor what medications you
are currently taking and about any allergies you have, especially to the contrast material that
may be used to enhance x-ray images.

You will be asked not to eat or drink anything after midnight on the night before your
procedure. In most cases, you should take any medications that you usually take, especially
blood pressure medications. These can be taken with some water in the morning before your
procedure. If you are on any blood thinning medication such as Coumadin, you should
check with your doctor about if and when you should stop the medication. It is a good idea
to check with the interventional radiologist about which medications you should take. You
should plan for an overnight at the hospital, and have someone drive you home when you
are ready to leave.

What does the equipment look like?

Angioplasty and vascular stenting require imaging equipment and special instruments.

The special instruments used in these procedures include a balloon catheter, which is a small
thin plastic tube with a tiny balloon at its tip, and a small wire mesh tube called a stent.
Balloons and stents come in varying sizes to match the size of the diseased artery.

The interventional radiologist will use high-resolution angiographic x-ray equipment to help
guide the catheter, balloon and stent to the site of the blockage and to check the results of
the procedure.

How does the procedure work?

Angioplasty uses an inflatable balloon mounted on a catheter that is passed to the site of the
blockage where it is inflated and deflated. In this process, the balloon expands the artery
wall, increasing the flow through the artery. The stent is placed at the site to hold the artery
open; this may be helpful in allowing the artery to heal in an open position.

How is the procedure performed?

To perform an angioplasty, an interventional radiologist or vascular surgeon makes a small
nick in the skin and inserts a balloon-tipped catheter. The catheter is threaded through the
artery until it reaches the site of the blockage, where the balloon is inflated, then deflated,
and removed. Expanding the balloon helps to restore blood flow by stretching the arterial
wall which increases the inner diameter of the artery.

Many angioplasty procedures also include the placement of a stent, a small, flexible tube
made of plastic or wire mesh to support the damaged artery walls. Stents are typically placed
over a balloon-tipped catheter, which is expanded, pushing the stent in place against the
artery wall. When the balloon is deflated and removed, the stent remains permanently in
place, acting like a scaffold for the artery.

Drug-coated (also called drug-eluting) stents have recently been approved for clinical use in
the coronary (heart) arteries by the U.S. Food and Drug Administration (FDA). These stents
are coated with a medication that is slowly released to help keep the blood vessel from re-
narrowing, a condition called restenosis. Restenosis, or re-narrowing of the artery can occur
with stents, which is why they are not used in all situations. If the artery has opened well
with the angioplasty, the stent may not be necessary.

What will I experience during the procedure?
An intravenous (IV) line will be inserted into your arm so that you can be given a mild
sedative and other medication necessary during the procedure. Although this sedative will
make you feel relaxed and drowsy, you will probably remain awake during the procedure.
Devices to monitor your heart rate and blood pressure will be attached to your body.

Next—depending on which artery your physician is using for the procedure—your groin
area, wrist, or arm will be cleaned, shaved and numbed with a local anaesthetic. A short tube
called a sheath is commonly inserted into the artery. Next, the physician will insert a catheter
(a long, flexible tube) through the sheath and advance it to the site of the blockage. An x-ray
camera connected to a video monitor will help the physician guide the catheter. You may
experience a dull pressure where the physician is working with the catheters, but no pain.

Once the catheter is in place, a contrast material may be injected into the artery and an
angiogram will be taken of the blocked artery to help identify the site of the blockage. With
x-ray guidance, a guide wire will then be advanced to the site, followed by the balloon-tipped
catheter. Once it reaches the blockage, the balloon will be inflated for several seconds to
several minutes. The same site may be repeatedly treated or the balloon may be moved to
other sites. It is common for patients to feel some mild discomfort when the balloon is
inflated because the artery is being stretched. Your discomfort should disappear as the
balloon is deflated.

Additional x-ray pictures will be taken to determine how much the blood flow has improved.
When your physician is satisfied that the artery has been opened enough, the balloon
catheter, guide wire and guiding catheter will be removed. The entire procedure usually lasts
between 30 minutes and two hours. The length of the procedure varies depending on the
time spent evaluating the vascular system prior to any therapy, as well as the complexity of
the treatment.

When the procedure is completed, you will be moved to a recovery room or your hospital
room. You may feel groggy from the sedative. The catheter insertion site may be bruised and
sore. If the sheath was inserted into your arm or wrist, it will be removed and the site will be
bandaged. If the catheter was inserted into your groin, you may need to lie in bed with your
legs straight for several hours. In some cases, your physician may use a device that seals the
small hole in the artery; this may allow you to move around more quickly.

For several hours, your catheter site will be checked for bleeding or swelling and your blood
pressure and heart rate will be monitored. Your physician may prescribe medication to relax
your arteries, to protect against spasm of the arteries and to prevent blood clots. If a contrast
material was used during the procedure, you will urinate often to rid your body of this
material. You may be asked to drink extra fluids.

Commonly, patients stay overnight and return home the day after the procedure. You will
typically be able to walk within two to six hours following the procedure.

After you return home, you should rest and drink plenty of fluids. You should avoid lifting
heavy objects, strenuous exercise and smoking for at least 24 hours (and smoking you should
avoid permanently since this is a major cause of atherosclerosis). If bleeding begins where
the catheter was inserted, you should lie down, apply pressure to the site and call your
physician. Any change in color in your leg, pain, or a warm feeling in the area where the
catheter was inserted should be reported to your physician.

You should be able to return to your normal routine by the following week.

If a stent was placed in your artery, you will be asked to take aspirin or another anti-platelet
drug daily; in some cases you may be given another blood-thinning medication in addition to
the anti-platelet medication. Blood tests will be done at frequent intervals during this period
to make sure you are being treated but not over treated. Magnetic Resonance Imaging (MRI)
can probably be done immediately following stent placement, but make sure that you notify
the MRI department that you recently had a stent. Metal detectors will not affect a stent.

Who interprets the results and how do I get them?

The interventional radiologist will judge the results of the angioplasty and stent placement by
comparing the pre- and post-procedure angiograms. If any narrowing remains in the artery,
it should not be greater than 30 percent of the normal vessel diameter. The results of your
procedure will be available immediately following the procedure.

If your angioplasty was performed on an artery leading to the kidneys to treat renal vascular
hypertension, a decline in blood pressure should occur in one to four weeks.

What are the benefits vs. risks?

        Compared to surgical interventions such as bypass surgery, balloon angioplasty and
        stent placement are much less invasive and relatively low-risk, low-cost procedures.

        These procedures are performed using local anaesthesia; no general anaesthetic is
        required.

        No surgical incision is needed—only a small nick in the skin that does not have to be
        stitched closed.

        You will be able to return to your normal activities shortly after the procedure.

Risks

        Major complications following angioplasty are uncommon. However, inserting the
        catheter can lead to injury of the artery. The balloon also poses a risk of blood clots
        or tearing the artery.

        When angioplasty is performed alone, blockages can recur, although most of these
        arteries can be opened again successfully. This can also occur when a stent is placed
        in the artery at the time of the angioplasty.
        Heavy bleeding from the catheter insertion site may require special medication or a
        blood transfusion.

        There is a risk of stroke when angioplasty and/or stenting are performed on the
        carotid artery.

        Stents may cause the formation of blood clots. Antibody-coated stents, which are
        designed to stimulate the body's repair system to heal itself, are currently being tested
        as a way to reduce the risk of blood clots and a re-narrowing of the artery, called
        restenosis. A combination of aspirin and an anti-platelet drug may reduce the risk of
        blood clots when taken for three days prior to the procedure and continued
        following angioplasty.

        A relatively rare complication associated with balloon angioplasty is abrupt vessel
        closure. This blockage in the area treated by the balloon angioplasty typically occurs
        within 24 hours of the procedure. If it happens, treatment with medication into the
        artery to dissolve clots followed by angioplasty or stenting may be appropriate. In
        some cases, emergency bypass surgery may be needed.

        Other rare complications include heart attack and sudden cardiac death.

What are the limitations of Angioplasty and Vascular Stenting?

Angioplasty with vascular stenting is just one way to treat narrowed or blocked arteries.
Medications and exercise are often the first step in treating atherosclerosis.

Regardless of which artery is blocked, angioplasty does not reverse or cure the underlying
disease of arteriosclerosis. It is important for patients to make lifestyle changes, including
eating a healthy diet that is low in saturated fat, getting adequate exercise and not smoking.
Individuals with diabetes, high blood pressure and high cholesterol need to follow the
treatment plan prescribed by their healthcare providers.

Angioplasty and stenting may have to be repeated if the same artery becomes blocked again,
a condition called restenosis. If a stent is placed at the time of the angioplasty, the chance of
restenosis may be reduced but can still occur.

Only about half of patients with renal hypertension caused by atherosclerosis have their
blood pressure successfully treated by angioplasty. By the time the procedure is done, many
of these patients have disease in small arteries within the kidney that does not respond to
angioplasty.

Angioplasty and vascular stenting for peripheral vascular disease (PVD) affecting arteries in
the pelvis and legs are less successful when there are multiple leg vessels that are narrowed
or when small vessels have to be opened. Any patient with PVD can benefit from eating a
proper diet, getting regular exercise and controlling blood cholesterol.
Angioplasty and stent placement in the carotid artery has been approved by the FDA, but
there is not much long-term data to know how well this works, or if there are potential
complications that can develop from stents being placed in the carotid arteries. A filter
device is used during stent placement to try and help keep blood clots and other plaques
from passing into the brain during the procedure, thereby lowering the risk of stroke.
Surgical repair has been done for many years and has been proven effective and safe when
done by skilled surgeons. You should discuss with your physician what the potential risks
and benefits are in your particular situation.


Provided for your information by the Canadian Association of Radiologists. Source: www.radiologyinfo.org

				
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