For more information, visit http://www.nhlbi.nih.gov/health/health-topics/topics/stents/

How Are Stents Used?

For the Coronary Arteries

Doctors may use stents to treat coronary heart disease (CHD). CHD is a disease in which a waxy substance called plaque (plak) builds up inside the coronary arteries. These arteries supply your heart muscle with oxygen-rich blood.

When plaque builds up in the arteries, the condition is called atherosclerosis (ath-er-o-skler-O-sis).

Plaque narrows the coronary arteries, reducing the flow of oxygen-rich blood to your heart. This can lead to chest pain or discomfort called angina (an-JI-nuh or AN-juh-nuh).

The buildup of plaque also makes it more likely that blood clots will form in your coronary arteries. If blood clots block a coronary artery, a heart attack will occur.

Doctors may use angioplasty and stents to treat CHD. During angioplasty, a thin, flexible tube with a balloon or other device on the end is threaded through a blood vessel to the narrow or blocked coronary artery.

Once in place, the balloon is inflated to compress the plaque against the wall of the artery. This restores blood flow through the artery, which reduces angina and other CHD symptoms.

Unless an artery is too small, a stent usually is placed in the treated portion of the artery during angioplasty. The stent supports the artery's inner wall. It also reduces the chance that the artery will become narrow or blocked again. A stent also can support an artery that was torn or injured during angioplasty.

Even with a stent, there's about a 10–20 percent chance that an artery will become narrow or blocked again in the first year after angioplasty. When a stent isn't used, the risk can be twice as high.

For the Carotid Arteries

Doctors also may use stents to treat carotid (ka-ROT-id) artery disease. This is a disease in which plaque builds up in the arteries that run along each side of your neck. These arteries, called carotid arteries, supply oxygen-rich blood to your brain.

The buildup of plaque in the carotid arteries limits blood flow to your brain and puts you at risk for a stroke.

Doctors use stents to help support the carotid arteries after they're widened with angioplasty. How well this treatment works in the long term still isn't known. Researchers continue to explore the risks and benefits of carotid artery stenting.

For Other Arteries

Plaque also can narrow other arteries, such as those in the kidneys and limbs. Narrow kidney arteries can affect kidney function and lead to severe high blood pressure.

Narrow arteries in the limbs, a condition called peripheral arterial disease (P.A.D.), can cause pain and cramping in the affected arm or leg. Severe narrowing can completely cut off blood flow to a limb, which could require surgery.

To relieve these problems, doctors may do angioplasty on a narrow kidney, arm, or leg artery. They often will place a stent in the affected artery during the procedure. The stent helps support the artery and keep it open.

For the Aorta in the Abdomen or Chest

The aorta is a major artery that carries oxygen-rich blood from the left side of the heart to the body. This artery runs through the chest and down into the abdomen.

Over time, some areas of the aorta's walls can weaken. These weak areas can cause a bulge in the artery called an aneurysm. An aneurysm in the aorta can burst, leading to serious internal bleeding. When aneurysms occur, they're usually in the abdominal aorta.

To help avoid a burst, doctors may place a fabric stent in the weak 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 that runs through the chest. Doctors also use stents to treat these aneurysms. How well the stents work over the long term still isn't known.

To Close Off Aortic Tears

Another problem that can occur in the aorta is a tear in its inner wall. If blood is forced into the tear, it will 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. If this happens, it usually occurs in the chest portion of the aorta.

Researchers are developing and testing fabric stents that will prevent blood from flowing into aortic tears. A fabric stent placed within the torn area of the aorta might help restore normal blood flow and reduce the risk of a burst aorta.

How Are Stents Placed?

Doctors place stents in arteries as part of a procedure called angioplasty. 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. The catheter will have a deflated balloon at its tip.

A stent is placed around the deflated balloon. Your doctor will move the tip of the catheter to the narrow section of the artery or to the aneurysm or aortic tear site.

Special x-ray movies will be taken of the tube as it's threaded through your blood vessel. These movies will help your doctor position the catheter.

For Arteries Narrowed by Plaque

Your doctor will use special dye to help show narrow or blocked areas in the artery. He or she will then move the catheter to the area and inflate the balloon.

As the balloon inflates, it pushes the plaque against the artery wall. This widens the artery and helps restore blood flow. The fully extended balloon also expands the stent, pushing it into place in the artery.

The balloon is deflated and pulled out along with the catheter. The stent remains in your artery. Over time, cells in your artery grow to cover the mesh of the stent. They create an inner layer that looks like the inside of a normal blood vessel.

Coronary Artery Stent Placement

Figure A shows the location of the heart and coronary arteries. Figure B shows the deflated balloon catheter and closed stent inserted into the narrow coronary artery. The inset image shows a cross-section of the artery with the inserted balloon catheter and closed stent. In figure C, the balloon is inflated, expanding the stent and compressing the plaque against the artery wall. Figure D shows the stent-widened artery. The inset image shows a cross-section of the compressed plaque and stent-widened artery.

A very narrow artery, or one that's hard to reach with a catheter, may require more steps to place a stent. At first, your doctor may use a small balloon to expand the artery. He or she then removes the balloon.

The small balloon is replaced with a larger balloon that has a collapsed stent around it. At this point, your doctor can follow the standard process of compressing the plaque and placing the stent.

Doctors use a special filter device when doing angioplasty and stent placement on the carotid arteries. The filter helps keep blood clots and loose pieces of plaque from traveling 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 described above. However, the stent used to treat an aneurysm is different. It's made out of pleated fabric instead of metal mesh, and it often has one or more tiny hooks.

The stent is expanded to fit tight against the artery wall. The hooks latch on to the wall of the artery, holding the stent in place.

The stent creates a new inner lining for that portion of the artery. Over time, cells in the artery grow to cover the fabric. They 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 a hospital and someone to take you home. Talk with your doctor about:

• 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, ask your doctor whether you need to take any extra steps during or after the procedure to avoid complications.

Before the procedure, your doctor may talk to you about medicines you'll likely need to take after the stent is placed. These medicines help prevent blood clots from forming in the stent.

You'll need to know how long you should take these medicines and why they're important. For more information about these medicines, go to "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 might 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. This allows you to follow your doctor's instructions.

Your doctor will numb the area where the catheter will be inserted. 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

Although this procedure takes only a few hours, it often requires a 2- to 3-day hospital stay.

Before the procedure, you'll be given medicine to help you relax. If your doctor is placing the stent in your abdominal aorta, you may receive medicine to numb your stomach area. However, you'll be awake during the procedure.

If your doctor is placing the stent in the chest portion of your aorta, you'll likely receive medicine to make you sleep during the procedure.

Once you're numb 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), your doctor will remove the catheter from your artery. The site where the catheter was inserted 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 look to see whether you're 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 insertion 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 a heart attack, stroke, or other serious problems.

If you have a metal stent, your doctor may 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 decide the best course of treatment.

Your risk of blood clots significantly increases if you stop taking the anticlotting medicine too early. Taking these medicines for as long as your doctor recommends is important. 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.

Also, anticlotting medicines can cause 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 for a 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 likely recommend 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.

Lifestyle Changes

Stents help prevent arteries from becoming narrow or blocked again in the months or years after angioplasty. However, stents aren't a cure for atherosclerosis or its risk factors.

Making lifestyle changes can help prevent plaque from building up in your arteries again. Talk with your doctor about your risk factors for atherosclerosis and the lifestyle changes you'll need to make.

Lifestyle changes may include changing your diet, quitting smoking, being physically active, losing weight, and reducing stress. You also should take all medicines as your doctor prescribes.

For more information about lifestyle changes, go to the treatment section of the Health Topics Atherosclerosis article.

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 blood vessel from the catheter
• Arrhythmias (irregular heartbeats)
• 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 that can occur after angioplasty is too much tissue growth within the treated portion of the artery. This can cause the artery to become narrow or blocked again. When this happens, it's called restenosis (RE-sten-no-sis).

Using drug-eluting stents can help prevent this problem. These stents are coated with medicine to stop excess tissue growth.

Treating the tissue around the stent with radiation also can prevent tissue growth. For this procedure, the doctor threads a wire through a catheter to the stent. The wire releases radiation and stops cells around the stent from growing and blocking the artery.

Restenosis of a Stent-Widened Coronary Artery

Figure A shows the coronary arteries located on the surface of the heart. Figure B shows a stent-widened artery with normal blood flow. The inset image shows a cross-section of the stent-widened artery. In figure C, tissue grows through and around the stent over time. This causes a partial blockage of the artery and abnormal blood flow. The inset image shows a cross-section of the tissue growth around the stent.

Risks Related to Stents

About 1–2 percent of people who have stented arteries develop a blood clot at the stent site. Blood clots can cause a 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 have. Your doctor may recommend lifelong treatment with aspirin.

Stents coated with medicine may raise your risk of dangerous blood clots. (These stents often are used to keep clogged heart arteries open.) However, research hasn't proven 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 problems can occur when surgery or a fabric stent is used to repair an aneurysm in the abdominal aorta. These problems 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 problem is very rare.

Another possible problem is the fabric stent moving further down the aorta. This sometimes happens years after the stent is first placed. The stent movement may require a doctor to place another fabric stent in the area of the aneurysm.

Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. Often, these advances depend on the willingness of volunteers to take part in clinical trials.

Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions. For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to stents, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

• http://clinicalresearch.nih.gov
• www.clinicaltrials.gov
• www.nhlbi.nih.gov/studies/index.htm
• www.researchmatch.org

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.

Links to Other Information About Stents

NHLBI Resources

• Aneurysm (Health Topics)
• Carotid Artery Disease (Health Topics)
• Coronary Angioplasty (Health Topics)
• Coronary Heart Disease (Health Topics)
• Peripheral Arterial Disease (Health Topics)

Non-NHLBI Resources

• Angioplasty (MedlinePlus)
• Angioplasty and Stent Placement—Carotid Artery (MedlinePlus)
• Angioplasty and Stent Placement—Heart (MedlinePlus)
• Angioplasty and Stent Placement—Peripheral Arteries (MedlinePlus)
• Stent (MedlinePlus)

Clinical Trials

• Children and Clinical Studies
• Clinical Trials (Health Topics)
• Current Research (ClinicalTrials.gov)
• NHLBI Clinical Trials
• NIH Clinical Research Trials and You (National Institutes of Health)
• ResearchMatch (funded by the National Institutes of Health)