A stent is a small, expandable tube placed inside a narrowed or blocked passage in the body to hold it open. Most commonly, stents are used in arteries that have become clogged with fatty buildup, restoring normal blood flow to the heart or other organs. But stents aren’t limited to blood vessels. They’re also used in bile ducts, the esophagus, airways, and the urinary tract to keep those passages open when disease threatens to close them off.
How Stents Work
The basic concept behind a stent is mechanical: a mesh-like cylinder props open a tube in the body the same way a scaffolding supports a tunnel. In arteries, fatty deposits called plaque gradually narrow the channel that blood flows through. Left untreated, this can starve the heart muscle of oxygen, causing chest pain or a heart attack. A stent pushes the plaque against the artery wall and holds the vessel open permanently.
Most stents are made of metal alloys. Nitinol, a nickel-titanium alloy with shape-memory properties, is the most widely used material in stent manufacturing. It can be compressed for delivery through a catheter and then spring back to its full size once in position. Stainless steel and cobalt-chromium alloys are also common. Some newer designs use materials that gradually dissolve in the body over roughly two years, leaving behind a healed, open artery with no permanent implant.
Types of Stents
The two main categories of coronary stents are bare-metal stents and drug-eluting stents. Bare-metal stents are simple mesh tubes. They do the job of holding an artery open, but scar tissue can grow through the mesh and re-narrow the vessel over time. In clinical studies, this re-narrowing (called restenosis) occurred in about 30% of patients with bare-metal stents within the first year.
Drug-eluting stents are coated with medication that slowly releases into the artery wall, suppressing the growth of scar tissue. This drops the one-year restenosis rate to roughly 10%. Because of this advantage, drug-eluting stents have become the standard choice for most patients.
Bioresorbable scaffolds represent a newer approach. These devices provide structural support while the artery heals, then dissolve completely over about two years. The idea is to avoid the long-term downsides of having a permanent metal implant, since permanent stents can cause ongoing low-grade inflammation that contributes to new plaque buildup inside the stent. Stent-related complications with permanent implants continue to accumulate at a rate of around 2% per year after the first year, with no clear plateau. Early results with bioresorbable designs suggest that complication rates level off after the scaffold dissolves, though research is ongoing.
What Happens During the Procedure
Coronary stent placement is a minimally invasive procedure, not open-heart surgery. A cardiologist accesses the bloodstream through a small puncture in either the wrist (radial artery) or the groin (femoral artery). A thin, flexible catheter is threaded through the artery up to the heart, guided by real-time X-ray imaging. Contrast dye is injected through the catheter so the arteries show up clearly on the screen, revealing exactly where the blockage sits.
Once the blockage is located, a fine guidewire is passed through the narrowed section. The stent, mounted over a tiny deflated balloon, is slid along this wire and positioned at the blockage. The balloon is then inflated, expanding the stent against the artery wall. This compresses the plaque and locks the stent in place. The balloon is deflated and withdrawn, leaving the stent behind as a permanent scaffold. Final images confirm the stent is properly positioned and blood is flowing freely.
In some cases, the cardiologist will inflate a balloon first to widen the artery before placing the stent. In others, the stent can be placed directly without this pre-dilation step.
Recovery After Stenting
Hospital stays vary depending on why the stent was placed. Someone who received a stent during a scheduled procedure for stable chest pain may go home the same day or the next morning. A patient who needed emergency stenting during a heart attack will typically stay longer for monitoring.
You should avoid strenuous exercise and heavy lifting for at least 24 hours after the procedure. The puncture site in your wrist or groin needs a short time to heal, and you may have a small bandage or closure device there. Most people return to normal daily activities within a few days, though your doctor will give you a more specific timeline based on your situation.
Medications After a Stent
After stent placement, you’ll take blood-thinning medications to prevent clots from forming inside the new stent. The standard approach combines low-dose aspirin with a second antiplatelet drug. How long you stay on both medications depends on the type of stent and why it was placed.
For patients with stable heart disease who receive a drug-eluting stent, the second medication is typically continued for at least six months. With a bare-metal stent, the minimum is one month. If the stent was placed during a heart attack or acute chest pain event, the combination therapy usually lasts at least 12 months. In all cases, low-dose aspirin is generally continued indefinitely.
Stopping these medications too early is one of the biggest risk factors for stent thrombosis, a dangerous complication where a blood clot forms inside the stent and suddenly blocks blood flow. In the early days of stenting, thrombosis rates ran as high as 16%. Modern techniques and antiplatelet therapy have brought that down to about 0.7% in the first year and 0.2% to 0.6% annually after that. The risk is higher for people treated during a heart attack (up to 3.4%) compared to those who have an elective procedure (0.3% to 0.5%).
Risk Factors for Complications
Certain conditions raise the likelihood of problems after stenting. Diabetes, kidney disease, and more extensive coronary artery disease are all associated with higher rates of stent thrombosis. Technical factors matter too: a stent that doesn’t fully expand, one placed in a very small vessel, or one that covers a long segment of artery is more prone to clotting. Stents placed at points where arteries branch are also at increased risk.
Re-narrowing of the artery inside a stent remains possible even with drug-eluting designs, though it’s far less common than it was with bare-metal stents. When it does occur, it can usually be treated with another stent or balloon procedure.
Stents Beyond the Heart
While coronary stents get the most attention, the same basic technology is used throughout the body. Biliary stents are placed in the common bile duct when it becomes blocked, most often by gallstones or tumors. This is one of the most common treatments for bile duct obstruction, and the stent can also be used to treat leaks in the bile or pancreatic ducts. Stents in the esophagus help keep the swallowing passage open in patients with tumors or severe scarring. Airway stents prop open the trachea or bronchi when they’re compressed by tumors or weakened by disease. Ureteral stents keep urine flowing from the kidneys to the bladder when kidney stones or other blockages threaten to cause a backup.
Non-vascular stents may be temporary or permanent depending on the condition. Some are designed to be removed after the underlying problem resolves, while others remain in place long-term.