What are stents?

Indications and Procedures

A stent is a stainless steel or Nitinol mesh tube implanted into a blood vessel to keep it propped open. The need for such a device arose in the 1980s. Doctors were performing a new procedure, called angioplasty, to clear narrowed arteries. The procedure involved inserting a small catheter into a blood vessel in the groin and threading it up to an area where a vessel was being narrowed by a fatty material called plaque. A small balloon on the end of the catheter was then inflated to push against the plaque, thus reducing the degree of narrowing of the vessel. This procedure was very successful, saving many patients the risks and complications of traditional surgeries. However, 35 to 45 percent of patients would experience renarrowing of the artery within four to six months because the plaque would spring back after the catheter was removed.

The idea of leaving a wire mesh tube to act as scaffolding to keep the plaque from springing back resulted in the first use of a stent device in 1986. The federal Food and Drug Administration (FDA) finally approved the use of stents in human patients in 1993. Since that time, many kinds of stents have become available. The first stents were made by soldering wires together around a pencil. Today, stents are made of steel etched by lasers that are controlled by computers.

Most stents are mounted on the balloon of an angioplasty catheter. Once the balloon reaches the narrowed area of the artery, it is inflated and the stent expands with it. The balloon is deflated and removed, leaving the deployed stent permanently in place to keep the vessel propped open.

Uses and Complications

Most stents are placed in the coronary arteries, the arteries that take blood to the heart. However, stents can be placed in any number of other blood vessels, including the peripheral arteries and veins (which serve the arms and legs), the carotid arteries (which serve the brain), or vessels in the abdomen.

Ironically, the complications that befall stents are similar to the problems they were designed to solve. Once a stent is placed, a mysterious scar may form on the stent, causing it to narrow. About 20 percent of stents will develop this problem. This scar is similar to, but not exactly the same as, the plaque in the artery. Studies are being done to reduce this problem. Coating the stent with materials that might retard the scar and radiating the stent to inhibit scar formation are being tried, and these measures appear promising. Clots may also form in the stent. For this reason, blood thinners and antiplatelet agents are commonly used to lessen the chances of clot formation on the stent.

Bibliography

American Heart Association. What Is a Stent? Dallas, Tex.: Author, 2005.

Dugdale, David. C., III. "Stent." MedlinePlus, March 22, 2013.

Heuser, Richard R., and Giancarlo Biamino, eds. Peripheral Vascular Stenting. 2d ed. New York: Taylor & Francis, 2005.

Milner-Fenwick. "What Is a Stent?" Health Library, 2013.

Serruys, Patrick W., and Benno Rensing, eds. Handbook of Coronary Stents. 4th ed. Florence, Ky.: Taylor & Francis, 2002.

White, Christopher J., et al. Quick Guide to Peripheral Vascular Stenting. Royal Oak, Mich.: Physicians’ Press, 2001.