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 percutaneous coronary intervention (PCI) (sometimes referred to as coronary angioplasty) and stents to treat CHD. During PCI, 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 PCI. 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 PCI.
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 PCI. When a stent isn't used, the risk can be as much as 10 times as high. Research has shown that as time goes by, people who have coronary artery stents are in less danger of risks from the surgery but more prone to the risks of chronic diseases, such as type 2 diabetes and renal failure.
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 PCI. Researchers continue to explore the risks and benefits of carotid artery stenting.
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 PCI 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.
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.
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 new kinds of stents that will prevent blood from flowing into aortic tears. A 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?
Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Stents, visit www.clinicaltrials.gov.
August 19, 2014
Gary H. Gibbons
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