A stent is a small mesh tube placed inside a passage in the body to hold it open. Most commonly, stents treat narrowed or weakened blood vessels, but they’re also used in bile ducts, airways, and the urinary tract. The specific reason for placing one depends on where the blockage or weakness is and what’s causing it.
Treating Blocked Heart Arteries
The most common use for stents is in the coronary arteries, the blood vessels that supply oxygen to the heart muscle. Over time, fatty deposits build up inside these arteries, a process called atherosclerosis. As the buildup worsens, it restricts blood flow to the heart. This can cause chest pain (angina) during physical activity, or in serious cases, trigger a heart attack when an artery becomes completely blocked.
During the procedure, a doctor threads a thin tube called a catheter through a blood vessel, typically starting at the wrist or groin, and guides it to the narrowed artery. A tiny balloon at the tip of the catheter inflates to push the buildup against the artery wall, and the stent expands into place. Once the balloon deflates and the catheter is removed, the stent stays behind as a permanent scaffold that keeps the artery open. The whole process is done through a small puncture rather than open surgery, and most people go home within a day or two.
Stent placement is recommended when chest pain from blocked arteries is getting worse, when blood flow is severely restricted, or as an emergency treatment during a heart attack. It restores blood flow quickly, which can limit damage to the heart muscle if performed soon after a heart attack begins.
Other Blood Vessel Uses
Stents aren’t limited to the heart. They’re placed in the carotid arteries (the major vessels in the neck that supply the brain) to prevent strokes. In people with significant carotid narrowing, stenting has achieved results comparable to traditional surgery for stroke prevention. Doctors typically recommend it for patients with narrowing of 50% or more who’ve already had symptoms like mini-strokes, or for those without symptoms whose arteries are at least 70% blocked.
In the legs, stents treat peripheral artery disease, where narrowed arteries reduce blood flow to the lower extremities and cause pain during walking. Stents can also be placed in the kidney arteries when narrowing threatens kidney function.
Stent Grafts for Aneurysms
An aneurysm is a dangerous bulge in an artery wall that can rupture if it grows too large. Stent grafts, which are fabric tubes supported by a metal mesh frame, treat aneurysms in a fundamentally different way than standard stents. Rather than simply propping an artery open, a stent graft creates an entirely new lining inside the vessel. Blood flows through the graft instead of pressing against the weakened wall, which lowers the risk of rupture. This approach is most commonly used for aneurysms in the aorta, the body’s largest artery. Some advanced versions have small openings that accommodate branching arteries, fitting the tree-like structure of the aorta and its surrounding vessels.
Stents Outside the Bloodstream
Not all stents go into blood vessels. Biliary stents are placed in the bile ducts, the small tubes that carry digestive fluid from the liver and gallbladder to the small intestine. When something blocks a bile duct, bile backs up and causes jaundice, pain, and infection. Common causes of bile duct blockages include pancreatic cancer, gallstones lodged in the duct, bile duct cancer, chronic inflammation that scars the ducts, and liver cancer or enlarged lymph nodes pressing on nearby structures. A biliary stent holds the duct open so bile can drain normally.
Stents also serve a role in the urinary tract, where ureteral stents keep the tube between the kidney and bladder open after kidney stone procedures or when a tumor compresses the ureter. In the lungs, airway stents hold open narrowed breathing passages caused by tumors, scarring, or other obstructions. Esophageal stents can open a blocked or narrowed food pipe, often in people with esophageal cancer that’s restricting swallowing.
Drug-Eluting vs. Bare-Metal Stents
One of the biggest problems after stent placement is the artery narrowing again, a process called restenosis. The body treats the stent as a foreign object and grows tissue over it. With older bare-metal stents, which are plain wire mesh, about 30% of arteries showed signs of re-narrowing on imaging studies.
Drug-eluting stents solved much of this problem. These stents are coated with medication that slowly releases over weeks to months, preventing excessive tissue growth around the stent. With current-generation drug-eluting stents, re-narrowing rates on imaging have dropped to around 12%, and the rate of re-narrowing severe enough to need another procedure is under 5%. Drug-eluting stents also cut the need for repeat procedures roughly in half compared to bare-metal versions and reduce the risk of blood clots forming inside the stent by about 35 to 40%. For stents placed in the heart’s most critical arteries, drug-eluting versions have even been linked to lower mortality. Today, drug-eluting stents are the standard choice for nearly all coronary procedures.
Researchers have also tested dissolving stents, called bioresorbable scaffolds, which are designed to support the artery temporarily and then break down over a couple of years. The first version approved in the U.S. was pulled from the market in 2017, just a year after approval, because of higher rates of complications. Newer designs using different materials are in development but none are currently available for routine use.
Risks of Stent Placement
Modern stents are reliable, but two main complications can occur. The first is stent thrombosis, where a blood clot forms inside the stent and suddenly blocks it. This is rare with current devices, happening in less than 1% of patients in the first year and roughly 0.2 to 0.4% per year after that. Overall rates of clotting within three years have dropped from about 3% to 1.5% as stent technology and blood-thinning medications have improved.
The second risk is restenosis, the gradual re-narrowing mentioned above. While imaging can detect it in roughly 10% of patients with newer drug-eluting stents, only about 5% develop symptoms significant enough to need treatment.
For non-vascular stents, the risks differ by location. Biliary stents can become blocked by tissue overgrowth or sludge, shift out of position, or lead to infection, bleeding, or inflammation of the pancreas.
Life After a Stent
After a coronary stent, the most important thing you’ll do is take blood-thinning medications to prevent clots from forming inside the stent. Current guidelines call for two anti-clotting medications taken together for at least 6 months after a planned procedure, or 12 months if the stent was placed during a heart attack or other acute event. For people with a high risk of bleeding, shorter courses of 1 to 3 months may be appropriate. Recent evidence suggests that stopping dual therapy around 9 months is associated with fewer bleeding complications without increasing the risk of clot-related problems.
Most people return to normal activities within a week, though heavy lifting is usually restricted for a short period to let the catheter insertion site heal. A stent treats the blockage, but it doesn’t cure the underlying disease. The same habits that led to artery buildup can cause new blockages elsewhere, so lifestyle changes like regular exercise, a heart-healthy diet, managing blood pressure and cholesterol, and quitting smoking are essential for long-term results.