Stents used in cardiology are metal coils that are used to hold a heart artery open. Stents are inserted as part of an angioplasty procedure.
During an angioplasty a fine tube is passed through an artery from the top of the leg or sometimes from the wrist. The tube is positioned so that its end is just at the beginning of one of the coronary arteries. A fine wire is passed down the tube and positioned across a narrowing in the artery. A small balloon on the end of a tube is passed down the wire and positioned inside the narrowing. The balloon is inflated squeezing the narrowing into the wall of the artery. The first balloon is removed and a second balloon is passed down the wire. This balloon has a stent mounted on it. When this balloon is inflated the stent is expanded and pushed into the wall of the artery. The stent holds the artery open whilst the wall of the artery undergoes a process of repair. The Mayo Clinic has produced a short cartoon to illustrate the procedure.
Currently there are two types of stent widely available. One, a bare metal stent is generally used in larger arteries and requires a shorter course of blood thinners after its use. The other is a drug eluting stent. These stents have a coating impregnated with a drug which modifies the artery’s repair process so that narrowings are rather less likely to reoccur within these stents. The downside of drug eluting stents is that they require a much longer course of blood thinners after their use.