Angioplasty and Vascular Stenting
What are Angioplasty and Vascular Stenting? Back top Top
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
very 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? Back top Top
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 these connections work better.
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 result when a piece of
plaque breaks off or a blood clot forms, 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? Back top Top
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? Back top Top
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? Back top Top
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? Back top Top
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? Back top Top
An
intravenous (IV) line will be inserted into your arm so that you can be
given a mild sedative and other medications as 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 anesthetic. 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 antiplatelet drug daily; in some cases you may be given another
blood-thinning medication in addition to the antiplatelet 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 have recently had a stent. Metal detectors will not affect a stent.
Who interprets the results and how do I get them? Back top Top
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? Back top Top
Benefits
- 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 anesthesia; no general anesthetic 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 antiplatelet 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? Back top Top
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. Back to Top |
