A primer for stent use

As the insertion of stents becomes a more standard procedure for treating heart and stroke problems, the U.S. government's National Heart, Lung, and Blood Institute (NHLBI) has provided a consumer's guide to how the tiny tubes are used and under what circumstances:

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.

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.

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.

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.