A stent is a small mesh tube that’s used to
treat narrowed or weakened arteries in the body.
You may have a stent placed in an artery as part of
a procedure called
angioplasty
(AN-jee-oh-plas-tee). Angioplasty can restore blood flow through narrowed or
blocked arteries. Stents help prevent arteries from becoming narrowed or
blocked again in the months or years after treatment with angioplasty. You may
also have a stent placed in a weakened artery to improve blood flow and to help
prevent the artery from bursting.
Stents are usually made of metal mesh, but sometimes
they’re made of fabric. Fabric stents, also called stent grafts, are used
in larger arteries. Some stents are coated with medicines that are slowly and
continuously released into the artery. These medicines help prevent the artery
from becoming blocked again.
How Are Stents Used?
Stents for Arteries in the Heart
With age and some health conditions, the inside
openings of the coronary arteries (arteries of the heart) tend to narrow due to
deposits of a fatty substance called plaque (plak). High cholesterol, diabetes,
and smoking can cause the arteries to narrow. This narrowing of the coronary
arteries can cause
angina
(chest pain) or lead to
heart
attack.
During
angioplasty,
doctors use an expanding balloon inside the artery to compress the plaque and
widen the passageway. The result is improved blood flow to the heart and a
decreased chance of heart attack.
Unless an artery is too small, doctors usually place
a stent in the treated portion of the artery during angioplasty. The stent
supports the inner artery wall and reduces the chance of the artery closing up
again. A stent also can keep an artery open that was torn or injured during
angioplasty.
When stents are placed in coronary arteries,
there’s a 1 in 5 chance that the arteries will close in the first 6 months
after angioplasty. When stents aren’t used, the risk of the arteries
closing can be twice as high.
Stents for the Carotid Arteries in the Neck
Both the right and left sides of your neck have
blood vessels called carotid (ka-ROT-id) arteries. These arteries carry blood
from the heart to the brain. Carotid arteries can become narrowed by plaque.
These plaque deposits limit blood flow to the brain and increase your risk for
stroke. Your chance of developing plaque in your carotid
arteries increases with age, and may increase if you smoke.
A new procedure uses stents to help keep the carotid
arteries fully open after they’re widened with angioplasty. Not all
hospitals offer this procedure. How effective it is long term is still not
known. The
National Institute of Neurological Disorders and Stroke
supports clinical studies to explore the risks and benefits of angioplasty and
stenting of carotid arteries.
Stents for Other Arteries
The arteries in the kidneys also can become
narrowed. This reduces blood flow to the kidneys, which can affect their
ability to control blood pressure. This can cause severe
high
blood pressure.
The arteries in the arms and legs also can narrow
with plaque over time. This narrowing can cause pain and cramping in the
affected limbs. If the narrowing is severe, it can completely cut off the blood
flow to a limb, which could require surgical treatment.
To relieve these problems, doctors may perform
angioplasty on the narrowed kidney, arm, or leg arteries. This procedure often
is followed by placing a stent in the treated artery. The stent helps keep the
artery fully open.
Stents for the Aorta in the Abdomen or Chest
The major artery coming out of the heart and
supplying blood to the body is called the aorta. The aorta travels through the
chest and then down into the abdomen. Over time, some areas of the walls of the
aorta can become weak. These weakened areas can cause a bulge in the artery
called an
aneurysm.
An aorta with an aneurysm can burst, leading to
potentially deadly internal bleeding. When aneurysms occur, they’re
usually in the part of the aorta in the abdomen. To help avoid a burst, doctors
place a fabric stent in the weakened area of the abdominal aorta. The stent
creates a stronger inner lining for the artery.
Aneurysms also can develop in the part of the aorta
in the chest. These aneurysms also can be treated with stents. But this new use
of stents is not offered by all hospitals, and how effective it is long term is
still not known.
Stents To Close Off Aortic Tears
Another problem that can develop in the aorta is a
tear in the inside wall. Blood can be forced into this tear, causing it to
widen and eventually block blood flow through the artery or burst. When this
occurs, it’s usually in the part of the aorta that’s in the
chest.
Fabric stents are being developed and used
experimentally to prevent aortic dissection by stopping blood from flowing into
the tear. Tears in the aorta reduce blood flow to the tissues the aorta serves.
A fabric stent placed within the torn area of the artery can help restore
normal blood flow and reduce the risk of a burst aorta. Stents to treat aortic
tears are still being researched. Only a few hospitals offer this
procedure.
How Are Stents Placed?
To place a stent, your doctor will make a small
opening in a blood vessel in your groin (upper thigh), arm, or neck. Through
this opening, your doctor will thread a flexible, plastic tube (catheter) with
a deflated balloon on the end. A stent may be placed around the deflated
balloon. The tip of the catheter is threaded up to the narrowed artery section
or to the
aneurysm
or aortic tear site. Special
x-ray “movies” are taken of the tube as it is
threaded up into your blood vessel. These movies help your doctor position the
catheter.
For Arteries Narrowed by Plaque
Once the tube is in the area of the artery that
needs treatment:
Your doctor uses a special dye to help see
narrowed areas of the blood vessel.
Your doctor inflates the balloon. It pushes
against the plaque and compresses it against the artery wall. The fully
extended balloon also expands the surrounding stent, pushing it into place in
the artery.
The balloon is deflated and taken out along with
the catheter. The stent remains in your artery. Cells in your artery eventually
grow to cover the mesh of the stent and create an inner layer that resembles
what is normally seen inside a blood vessel.
Coronary Artery Stent
Placement
The illustration shows the placement
of a stent in a coronary artery with plaque buildup. The coronary artery is
located on the surface of the heart. Figure A shows the deflated balloon
catheter and closed stent inserted into the narrowed coronary artery. The
insert image on figure A shows a cross-section of the artery with the inserted
balloon catheter and closed stent. In figure B, the balloon is inflated,
expanding the stent and compressing the plaque to restore the size of the
artery. Figure C shows normal blood flow restored in the stent-widened artery.
The insert image on figure C shows a cross-section of the compressed plaque and
stent-widened artery.
The animation below shows coronary angioplasty and
stent placement. Click the "start" button to play the animation. Written and
spoken explanations are provided with each frame. Use the buttons in the lower
right corner to pause, restart, or replay the animation, or use the scroll bar
below the buttons to move through the frames.
The animation shows how a doctor
inserts a tube called a balloon catheter into a coronary artery narrowed by
plaque. The balloon catheter compresses the plaque, widens the artery, and
restores blood flow. Through the catheter, a stent is placed in the artery to
help maintain the restored blood flow.
A very narrow artery, or one that is difficult to
reach with the catheter, may require more steps to place a stent. This type of
artery usually is first expanded by inflating a small balloon. The balloon is
then removed and replaced by another larger balloon with the collapsed stent
around it. At this point, your doctor can follow the standard practice of
compressing the plaque and placing the stent.
When
angioplasty
and stent placement are performed on carotid arteries, a special filter device
is used. The filter helps keep blood clots and loose pieces of plaque from
passing into the bloodstream and brain during the procedure.
For Aortic Aneurysms
Placing a stent to treat an aneurysm in an artery is
slightly different than treating an artery narrowed by plaque. The stent used
to treat an aneurysm is made out of pleated fabric, often with one or more tiny
hooks.
Once the catheter is positioned at the aneurysm
site, the stent is threaded through the tube to the area that needs treatment.
Then, your doctor places a balloon inside the stent. The balloon is inflated to
expand the stent and have it fit tight against the artery wall. The hooks on
the stent latch on to the artery wall to anchor the stent. Your doctor then
removes the balloon and catheter, leaving the fabric stent behind.
The stent creates a new inner lining for that
portion of the artery. Cells in the artery eventually grow to cover the fabric
and create an inner layer that resembles what’s normally seen inside a
blood vessel.
What To Expect Before a Stent Procedure
Most stent procedures require an overnight stay in
the hospital and someone to take you home. Discuss with your doctor:
When to stop eating and drinking before coming to
the hospital
What medicines you should or shouldn’t take
on the day of the procedure
When to come to the hospital and where to go
You also should let your doctor know if you have
diabetes, kidney disease, or other conditions that may require taking extra
steps during or after the procedure to avoid complications.
What To Expect During a Stent Procedure
For Arteries Narrowed by Plaque
This procedure usually takes a few hours.
Before the procedure starts, you will get medicine
to help you relax. You will be on your back and awake during the procedure so
you can follow the doctor’s instructions. The area where the catheter is
inserted will be numbed and you won’t feel the doctor threading the
catheter, balloon, or stent inside the artery. You may feel some pain when the
balloon is expanded to push the stent into place.
For Aortic Aneurysms
This procedure takes a few hours. It usually
requires a 2- to 3-day stay in the hospital.
Before the procedure, you will be given medicine to
help you relax. If a stent is placed in the abdominal portion of the aorta,
your doctor may give you a regional anesthetic. This will make you numb from
the area of the stent placement down, but it will allow you to be awake during
the procedure. If a stent is placed in the chest portion of the aorta, usually
a general anesthetic will be used, which will make you sleep through the
procedure.
Once you’re numbed or asleep, your doctor will
make a small cut in your groin (upper thigh). The doctor will insert a catheter
into the blood vessel through this cut. Sometimes, two cuts (one above each
leg) are needed to place fabric stents that come in two parts. You will not
feel the doctor threading the catheter, balloon, or stent into the
artery.
What To Expect After a Stent Procedure
Recovery
After either type of stent procedure (for arteries
narrowed by plaque or aortic aneurysm), once the stent has been placed and the
balloon and catheter have been removed, the tube insertion site will be
bandaged. A small sandbag or other type of weight may be put on top of the
bandage to apply pressure to help prevent bleeding. You will recover in a
special care area where your movement will be limited.
While you’re in recovery, a nurse will check
your heart rate and blood pressure regularly. The nurse also will see if
there’s any bleeding from the insertion site. Eventually, a small bruise
and sometimes a small, hard “knot” will appear at the insertion site.
This area may feel sore or tender for about a week.
You should let your doctor know if:
You have a constant or large amount of bleeding
at the site that can’t be stopped with a small bandage.
You have any unusual pain, swelling, redness, or
other signs of infection at or near the insertion site.
Common Precautions After a Stent Procedure
After a stent procedure, your doctor may have you
take blood-thinning or anticlotting medicines for at least a few months. These
medicines help prevent the development of blood clots in the stent. If your
stent is coated with medicine, your doctor may advise you to take aspirin and
an anticlotting medicine for months to years to lower the risk of blood
clots.
You should avoid vigorous exercise and heavy lifting
for a short time after the procedure. Your doctor will discuss with you when
you can resume normal activities.
If you have a metal stent placed, you shouldn’t
have a
magnetic resonance imaging (MRI) test within the first couple
of months after the procedure. Metal detectors used in airports and other
screening areas don’t affect stents.
If you have an aortic fabric stent, your doctor will
probably recommend that you have followup imaging tests (for example,
x ray) within the first year of having the procedure, and
yearly imaging tests after that.
What Are the Risks of Having a Stent?
Risks Related to Angioplasty
Any medical procedure has risks, but major
complications from
angioplasty
are rare. The most common risks from angioplasty include:
Bleeding from the site where the catheter was
inserted into the skin
Damage to the blood vessel from the catheter
Infection
Allergic reaction to the dye used during the
procedure
Another common problem after angioplasty is too much
tissue growth within the treated portion of the artery. This can cause the
artery to narrow or close again, which is called restenosis. This problem is
often avoided with the use of newer stents coated with medicines that help
prevent too much tissue growth. Treating the tissue around the stent with
radiation also can prevent tissue growth. For this procedure, the doctor puts a
wire through a catheter to where the stent is placed. The wire releases
radiation and stops cells around the stent from growing and blocking the
artery.
Restenosis of a Stent-Widened
Coronary Artery
The illustration shows the
restenosis of a stent-widened coronary artery. The coronary artery is located
on the surface of the heart. In figure A, the expanded stent compresses plaque,
allowing normal blood flow. The inset image on figure A shows a cross-section
of the compressed plaque and stent-widened artery. In figure B, over time, the
plaque grows through and around the stent, causing a partial blockage and
abnormal blood flow. The inset image on figure B shows a cross-section of the
growth of the plaque around the stent.
Risks Related to Stent
About 1 to 2 percent of people with a stented artery
develop a blood clot at the stent site. Blood clots can cause
heart
attacks,
strokes, or other serious problems. The risk of blood clots is
greatest during the first few months after the stent is placed in the artery.
Your doctor will probably have you take blood-thinning or anti-clotting
medicines for at least a few months after having a stent procedure to prevent
blood clots.
Stents coated with medicine (drug-releasing stents),
which are often used to keep clogged heart arteries open, may increase your
risk for potentially dangerous blood clots. But an expert Food and Drug
Administration panel found no conclusive evidence that these stents increase
the chances of having a heart attack or dying, if used as recommended. Patients
with drug-releasing stents are usually advised to take aspirin and an
anti-clotting drug, such as clopidogrel, for months to years to lower the risk
of blood clots.
Risks Related to Aortic Stents in the Abdomen
Whenever an
aneurysm
in the abdomen region of the aorta is repaired with either surgery or with a
fabric stent, few rare but serious complications can occur, including:
A burst artery (aneurysm rupture).
Blocked blood flow to the stomach or lower
body.
Paralysis in the legs due to interruption of
blood flow to the spinal cord. This is an especially rare complication.
Another possible complication is the fabric stent
moving further down the aorta. This sometimes happens years after the stent is
first placed. Such stent movement may require a doctor to place another fabric
stent in the area of the aneurysm.
Key Points
A stent is a small mesh tube that’s used to
treat narrowed or weakened arteries in the body.
A stent is usually placed in an artery after it
has been widened with a procedure called
angioplasty.
Angioplasty and stents are often used to relieve
chest pain and minimize damage to the heart due to narrowed or blocked heart
arteries. They also are used in other arteries in the body to prevent loss of
blood flow to the limbs, and to prevent weakened arteries from bursting.
Stents are usually made of metal mesh, but
sometimes they’re made of fabric. Fabric stents, also called stent grafts,
are used in larger arteries.
Stents can be placed in the carotid arteries or
the aorta, and in leg, arm, or kidney arteries to prevent
stroke or loss of a limb, or to relieve
high
blood pressure.
Stents are used to repair aortic arteries that
have bulges called
aneurysms.
To place a stent, your doctor makes a small
opening in a blood vessel in your groin (upper thigh), arm, or neck. Through
this opening, a flexible, plastic tube (catheter) with a collapsed balloon and
stent on the end is threaded up to the area of the artery that needs treatment.
The balloon is then expanded, which widens the narrowed artery and pushes the
stent into place.
The placement of a stent only takes a few hours.
You may have to stay in the hospital for up to 3 days, depending on which
artery was treated. You may feel some pain when the balloon is expanded to push
a stent into place.
To prevent blood clots, you will probably take
blood-thinning medicines for at least a few months after having a stent
placed.
Vigorous exercise and heavy lifting should be
avoided for a short time after a stent procedure. Your doctor will discuss with
you when you can resume normal activities.
Developing a blood clot at the stent site is the
main risk of having a stent. Blood clots can cause
heart
attack, stroke, and other serious problems. This risk is greatest during
the first few months after the stent is placed in the artery. Taking
blood-thinning or anticlotting medicines can decrease the risk for a blood
clot. There also are risks related to angioplasty and to the placement of the
stent.
Patients with drug-releasing stents are usually
advised to take aspirin and an anticlotting drug, such as clopidogrel, for
months to years to lower the risk of blood clots.
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