A cardiac stent is a small tube-shaped device made of thin metal mesh and is used to treat coronary artery disease. During a procedure called percutaneous coronary intervention, the stent is inserted into a previously blocked coronary artery for the purpose of keeping the artery expanded and open. A cardiac stent often is inserted into a coronary artery during an angioplasty procedure to widen arteries that have narrowed.
In this procedure, the narrowed artery is mechanically widened with the insertion of a balloon catheter. The stent is mounted on the balloon catheter so that it can be placed after the artery has been widened. The incision through which the catheter is inserted typically is made in the femoral artery of the groin or in the arm. The device is then carefully threaded through the incision and along the artery until it reaches the narrowed portion of the cardiac artery. Pressurized water is passed through the catheter to inflate the balloon and the stent and to widen the artery. Once the stent is in position and stable, the balloon is deflated, and the catheter is removed.
Cardiac stent placement is not always a permanent solution to the problem of narrowed arteries. One problem is that the stent is a foreign object and can potentially trigger a response from the patient's immunity system. This response typically involves inflammation, leading to the development of scar tissue that can engulf the stent and narrow the arteries. This inflammation also can promote the formation of blot clots at the location.
A new type of cardiac stent called a drug-eluting stent was developed to help solve this problem. The first stents used were called bare-metal stents and were simply a bare wire mesh. A drug-eluting stent is a bare-metal stent coated with a film of anti-proliferative medication. Once the stent is in place, it begins slowly releasing small amounts of the drug, reducing the rate of cell proliferation at the site. This reduces the intensity of the immune response to the stent and helps prevent scar tissue from forming.
Drug-eluting stents are considered superior to bare-metal stents. Even so, there are risks involved. The main risk of this type of stent is an allergic reaction to the drug that is released. Allergic reaction is extremely rare but can be fatal when it occurs. Another problem is that even though cell proliferation is considerably slowed, the risk of blood clot formation still exists. To combat this problem, someone who is fitted with any type of cardiac stent must take blood thinners to reduce the risk of clotting.