A stent is a medical device that is used to prop open an obstructed or damaged artery. Stents are commonly used in cardiac angioplasty surgery and, according to the American Heart Association, 70 percent of angiolasty procedures include the placement of a stent. Stents are permanently added to an area of occlusion, reducing the restenosis that can occur after balloon angioplasty. Some occlusions can recur following stent placement, and various materials and methods are available to accommodate the particular needs of the patient to minimize this risk.
Metal
Also known as bare metal stents, these lattice-shaped tubes are made of metal mesh. They have no type of coating around the metal, as other types of stents have, and are placed in the artery simply for their structural support in holding a blood vessel open after it has been dilated during angioplasty--a surgical technique for widening obstructed blood vessels. As the artery heals from the surgery, tissue grows around the stent to hold it in place. Problems with this type of stent arise when this tissue overgrows and creates its own form of occlusion of the artery, necessitating further surgical procedures. According to researchers Anthony A. Bavry, MD, MPH; Deepak L. Bhatt, MD, in the 2006 "Journal of Invasive Cardiology," while bare metal stents are more effective at reducing the need for repeat surgeries than balloon angioplasty, they they have not been shown to reduce the rate of heart attacks or deaths.
Drug-Eluting
These stents are infused with drugs that are released slowly to inhibit the growth of scar tissue, such as occurs with bare metal stents. Drug-eluting stents keep the blood vessel open and lessen the likelihood of requiring repeat surgery, according to the Mayo Clinic. These stents have been in use in the U.S. since 2003 with excellent reduction in repeat procedures, and by 2006 were being used in 90 percent of stent placements. However, due to some concern and controversy regarding their long term safety, use of these stents has declined. Specifically, it has been observed that the body reacts to the polymer coating of the stents with inflammation and increased chance of thrombosis, according to the November 2007 "Current Cardiology Reports." The controversy continues, with recent reports coming out in support of drug-eluting stents, says the website Med Page Today.
Plastic
Plastic stents provide an alternative to metal stents, which can damage blood vessels. Made of a lactic acid polymer, this stent is absorbed by the body over 18 to 24 months, during which time the blood vessel heals and strengthens, so that by the time the stent dissolves the blood vessel is repaired and the stent is no longer needed. Studies conducted by researchers at the Shiga Medical Center for Adults in Japan showed a lower rate of restenosis than for patients with metal stents. Additionally, these stents, because they dissolve, are preferable for use in children, who outgrow metal stents, leading them to become loose and posing a hazard.
