A stent is a small mesh tube that's used to treat
narrowed or weakened arteries in the body. Arteries are blood vessels that
carry blood away from your heart to other parts of your body.
You may have a stent placed in an artery as part of
a procedure called
angioplasty
(AN-jee-oh-plas-tee). Angioplasty restores blood flow through narrowed or
blocked arteries. Stents help prevent the arteries from becoming narrowed or
blocked again in the months or years after angioplasty.
You also may have a stent placed in a weakened
artery to improve blood flow and to help prevent the artery from bursting.
Stents usually are 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 stents are called
drug-eluting stents. The medicines help prevent the artery from becoming
blocked again.
How Are Stents Used?
For the Coronary Arteries
In a condition called
coronary
heart disease (CHD), or coronary artery disease, a fatty substance called
plaque (plak) can build up inside the coronary (heart) arteries. Plaque narrows
the coronary arteries, reducing the flow of oxygen-rich blood to the heart
muscle.
High
blood cholesterol,
high
blood pressure, diabetes, and smoking may lead to CHD. When your coronary
arteries are narrowed or blocked, oxygen-rich blood can't reach your heart
muscle. This can cause
angina
(an-JI-nuh or AN-juh-nuh; chest pain) or a
heart
attack.
During
angioplasty,
doctors use an expanding balloon inside the artery to compress plaque and widen
the passage. Angioplasty improves blood flow to the heart, which reduces angina
and other CHD symptoms.
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 becoming
narrowed or blocked again. A stent also can support an artery that was torn or
injured during angioplasty.
When stents are used in coronary arteries, there's
about a 10 to 20 percent chance that the arteries will renarrow or close in the
first year after angioplasty. When stents aren't used, the risk of the arteries
closing can be twice as high.
For the Carotid Arteries
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. Plaque also can narrow the carotid arteries. When
this happens, the condition is called
carotid
artery disease.
Plaque deposits in the carotid arteries limit blood
flow to the brain and put you at risk for
stroke. The same factors that raise your risk for CHD also
increase your risk for carotid artery disease.
Stents are used to help keep the carotid arteries
fully open after they're widened with angioplasty. How well this treatment
works long term still isn't known. Research is ongoing to explore the risks and
benefits of carotid artery stenting.
For Other Arteries
The arteries in the kidneys may become narrowed.
This reduces blood flow to the kidneys, which can affect their function and
ability to control blood pressure. This can cause severe high blood
pressure.
Plaque can narrow the arteries in the arms and legs
over time. When this happens, the condition is called
peripheral
arterial disease, or P.A.D.
This narrowing can cause pain and cramping in the
affected limbs. If the narrowing is severe, it can completely cut off blood
flow to a limb, which could require surgery.
To relieve these problems, doctors may do
angioplasty on a narrowed kidney, arm, or leg artery. This procedure often is
followed by placing a stent in the treated artery. The stent helps keep the
artery fully open.
For the Aorta in the Abdomen or Chest
The major artery coming out of the heart that
supplies blood to the body is called the aorta. The aorta travels through the
chest and down into the abdomen. Over time, some areas of the aorta's walls 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 may 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. How well these
stents work over the long term still isn't known.
To Close Off Aortic Tears
Another problem that can develop in the aorta is a
tear in its inner wall. Blood can be forced into this tear, causing it to
widen.
The tear can reduce blood flow to the tissues that
the aorta serves. Over time, the tear can 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 tears by stopping blood from flowing into the
tear. A fabric stent placed within the torn area of the aorta can help restore
normal blood flow and reduce the risk of a burst aorta. Researchers are still
studying stents to treat aortic tears.
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 thin, flexible tube called a catheter
with a deflated balloon on its end.
A stent may be placed around the deflated balloon.
The tip of the catheter is threaded up to the narrowed section of the artery or
to the aneurysm
or aortic tear site.
Special x-ray movies are taken of the tube as it's
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 looks like
the inside of a normal blood vessel.
Coronary Artery Stent
Placement
The illustration shows the placement
of a stent in a coronary artery with plaque buildup. Figure A shows the
deflated balloon catheter and closed stent inserted into the narrowed coronary
artery. The inset 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 inset image on figure C shows a cross-section of the compressed
plaque and stent-widened artery.
The animation below shows 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's hard to reach
with a 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 done 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 traveling up to the brain during the procedure.
For Aortic Aneurysms
The procedure to place a stent in an artery with an
aneurysm is very similar to the one used for an artery narrowed by plaque. The
stent used to treat an aneurysm is different, though. It’s made out of
pleated fabric, often with one or more tiny hooks.
Once the stent has been placed and expanded to fit
tight against the artery wall, the hooks on the stent latch on to the artery
wall. This anchors the stent.
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 looks like the inside of a normal 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
If you have diabetes, kidney disease, or other
conditions, talk with your doctor about whether you need to take any extra
steps during or after the procedure to avoid complications.
Before the procedure, your doctor may talk with you
about medicines you'll probably need to take after the stent is placed. These
medicines help prevent blood clots from forming.
It's important that you know how long you should
take these medicines and why they're important. For more information on these
medicines, see
"What
to Expect After a Stent Procedure."
What To Expect During a Stent Procedure
For Arteries Narrowed by Plaque
This procedure usually takes about an hour. It could
take longer if stents are inserted into more than one artery during the
procedure.
Before the procedure starts, you'll get medicine to
help you relax. You'll 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'll be given medicine to
help you relax. If a stent is placed in the abdominal aorta, your doctor may
give medicine to numb the area, but you'll be awake during the procedure.
If a stent is placed in the chest portion of the
aorta, your doctor will likely give you medicine to make you sleep through the
procedure.
Once you're numbed or asleep, your doctor will make
a small cut in your groin (upper thigh). He or she will insert a catheter into
the blood vessel through this cut.
Sometimes, two cuts (one in the groin area of 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 aneurysms), the catheter will be removed and 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 and help prevent bleeding. You'll
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 whether
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
Blood Clotting Precautions
After a stent procedure, your doctor will likely
recommend that you take aspirin and another anticlotting medicine. These
medicines help prevent blood clots from forming in the stent. A blood clot can
lead to
heart
attack,
stroke, or other serious problems.
If you have a metal stent, your doctor will likely
recommend aspirin and another anticlotting medicine for at least 1 month. If
your stent is coated with medicine, your doctor may recommend aspirin and
another anticlotting medicine for 12 months or more. Your doctor will work with
you to determine the best course of treatment.
The risk of developing a blood clot significantly
increases if you stop taking the anticlotting medicine too early. It's
important to take these medicines for as long as your doctor recommends. He or
she may recommend lifelong treatment with aspirin.
If you're considering surgery for some other reason
while you're on these medicines, talk to your doctor about whether it can wait
until after you've stopped the medicine. Anticlotting medicines may increase
the risk of bleeding.
In addition to an increased risk of bleeding,
anticlotting medicines can cause other side effects, such as an allergic rash.
Talk to your doctor about how to reduce the risk of these side effects.
Other Precautions
You should avoid vigorous exercise and heavy lifting
for a short time after the stent procedure. Your doctor will let you know when
you can go back to your normal activities.
If you have a metal stent, 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. Your stent shouldn't cause metal detectors to go off.
If you have an aortic fabric stent, your doctor will
probably recommend that you have followup imaging tests (for example, chest
x ray) within the first year of having the procedure. After the
first year, he or she may recommend yearly imaging tests.
What Are the Risks of Having a Stent?
Risks Related to Angioplasty
Angioplasty, the procedure used to place stents, is a common medical
procedure. Angioplasty carries a small risk of serious complications, such
as:
Bleeding from the site where the catheter was
inserted into the skin
Damage to the kidneys caused by the dye used
during the procedure
An allergic reaction to the dye used during the
procedure
Infection
Another 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
(RE-sten-no-sis).
This problem often is avoided with the use of
drug-eluting stents. These stents are 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. 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, tissue 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 tissue around the stent.
Risks Related to Stents
About 1 to 2 percent of people who have a stented
artery develop a blood clot at the stent site. Blood clots can cause
heart
attack,
stroke, 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 likely
recommend that you take aspirin and another anticlotting medicine, such as
clopidogrel, for at least 1 month or up to a year or more after having a stent
procedure. These medicines help prevent blood clots.
The length of time you need to take anticlotting
medicines depends on the type of stent you get. Your doctor may recommend
lifelong treatment with aspirin.
Stents coated with medicine, which often are used to
keep clogged heart arteries open, may increase your risk for potentially
dangerous blood clots. However, no conclusive evidence shows that these stents
increase the chances of having a heart attack or dying, if used as
recommended.
Risks Related to Aortic Stents in the Abdomen
Although rare, a few serious complications can occur
when surgery or a fabric stent is used to repair an
aneurysm in the abdominal region of the aorta. These complications
include:
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 complication is very rare.
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.
You may have a stent placed in an artery as part
of a procedure called
angioplasty.
Angioplasty restores blood flow through narrowed or blocked arteries. Stents
help prevent the arteries from becoming narrowed or blocked again in the months
or years after angioplasty.
You also may have a stent placed in a weakened
artery to improve blood flow and help prevent the artery from bursting.
Stents usually are 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 coronary arteries,
carotid arteries, and the arteries in the kidneys and limbs. Stents also are
used to repair
aneurysms
in the aorta, the major artery that carries oxygen-rich blood from the heart to
the body.
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 thin, flexible tube called a catheter with a deflated 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 takes about an hour or
more. You may have to stay in the hospital for up to 3 days, depending on which
artery is treated.
To prevent blood clots after having a stent
placed, your doctor will likely recommend that you take aspirin and another
anticlotting medicine for at least 1 month or up to a year or more, depending
on the type of stent you get. It's very important to continue taking these
medicines for as long as your doctor recommends.
Avoid vigorous exercise and heavy lifting for a
short time after a stent procedure. Your doctor will let you know when you can
go back to your normal activities.
Angioplasty is a common medical procedure.
There's a small risk of serious complications, such as bleeding at the catheter
insertion site, damage to the blood vessel where the catheter was inserted,
irregular heartbeats, infection, and damage to the kidneys or an allergic
reaction due to the dye used during the procedure.
Another problem after angioplasty is too much
tissue growth within the treated portion of the artery. This is called
restenosis.
About 1 to 2 percent of people who have a
stented artery develop a blood clot at the stent site. The risk of blood clots
is greatest during the first few months after the stent is placed in the
artery. Taking aspirin and another anticlotting medicine can lower the risk for
blood clots.
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