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 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?

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. 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.

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.

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

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

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.

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.

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 anticlotting 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 anticlotting 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.

Links to Other Information About Stents

NHLBI Resources

    • Aneurysm (Diseases and Conditions Index)
    • Angioplasty (Diseases and Conditions Index)

Non-NHLBI Resources

    • Angioplasty (MedlinePlus)

Clinical Trials

    • Current Research (ClinicalTrials.gov)

Reproduced from the National Heart, Lung and Blood Institute of the National Institutes of Health. May 2007.