According to reports, Sen. Bernie Sanders (D-VT), a Democratic presidential candidate, was hospitalized for an emergency procedure to insert stents into his heart. A stent is a wire mesh tube used to prop open an artery permanently.

When a coronary artery (an artery feeding the heart muscle) is narrowed by a buildup of fatty deposits called plaque, it can reduce blood flow. If blood flow is reduced to the heart muscle, chest pain can result. If a clot forms and completely blocks the blood flow to part of the heart muscle, a heart attack results. Stents help keep coronary arteries open and reduce the chance of a heart attack.

According to Robert A. Harrington, MD, FAHA, president of the American Heart Association, “By clinical guidelines, an artery should be about 70% blocked before a stent is placed. This is a fairly common heart procedure—about 434,000 procedures were done in 2014 in the US Often patients require more than one stent.”

To open a narrowed artery, a doctor may do a procedure called a percutaneous coronary intervention (PCI) or angioplasty. In it, a balloon-tipped tube (catheter) is inserted into an artery and moved to the point of blockage. Then the balloon is inflated. This compresses the plaque and opens the narrowed spot. When the opening in the vessel has been widened, the balloon is deflated and the catheter is withdrawn. The stent stays in the artery permanently and holds it open. This improves blood flow to the heart muscle and relieves symptoms (usually chest pain).

Most angioplasty procedures are done using stents. In certain patients, stents reduce the re-narrowing that sometimes occurs after balloon angioplasty or other procedures that use catheters. Patients who have angioplasty and stents recover from these procedures much faster than patients who have coronary artery bypass surgery (CABG). They have much less discomfort, too.

There are two types of stents. Stents that are covered with drugs that help keep the blood vessel from reclosing are called drug-eluting stents. Stents not coated with drugs are called bare metal stents.

Following a stent procedure the patient will need to take one or more antiplatelet agents. These medicines keep platelets from clumping together and forming blood clots in the stent and blocking the artery. One antiplatelet agent is aspirin. A second type is called a P2Y12 inhibitor. When aspirin and a P2Y12 inhibitor are used together it is called dual antiplatelet therapy (DAPT).