An endovascular stent is a small flexible mesh tube that is placed within the lining of a damaged blood vessel to open the vessel and permanently hold it open. Endovascular stents are either bare metal or fabric. Metal stents represent the first generation of stents, are made entirely of metal wire mesh, and do not carry medication. On the other hand, coated stents are a newer development of endovascular stents; these can be either coated with a synthetic fabric, or the stent itself can be woven from fabric and metal strands. Fabric stents also are able to contain time-released medications within their fibers.
An endovascular stent, also called an intravascular stent, is regularly used during percutaneous angioplasty (PTA), commonly shortened to just angioplasty. This is a procedure used to insert a stent into narrowed or blocked arteries or veins to dilate them; a small balloon on the end of a catheter is inflated after the vessel is punctured and the stent is inserted. When this procedure is performed on the major arteries of the heart, or coronary vessels, it is termed percutaneous transluminal coronary angioplasty (PTCA).
Stents are widely utilized in endovascular surgery, a type of surgery for accessing the major blood vessels around the heart or abdominal area without needing to extensively cut through body tissues. A fabric stent was, in 2010, the most commonly used type of endovascular stent for treating aneurysms of the major coronary arteries, or arteries associated with the heart. When a fabric stent is used to repair a major artery, it is called a stent-graft.
Stent-grafts are used to repair aneurysms. An aneurysm is basically a bulge in part of the aorta that is caused by a weakened aortic wall. When it occurs in the abdomen, it is called an abdominal aortic aneurysm (AAA). If a traumatic aortic injury were to occur, such as a rupture of the aneurysm, neither metal nor fabric endovascular stents could be used for repair. This is because of the nature of the wall of the aneurysmal vessel.
The arterial wall is in layers, with the most delicate layer being nearest the area where blood flows in the lumen, or central core, of the artery. This layer can become torn, and this is known as an aortic tear. Blood within the artery, similar to a river current, can gradually erode the section of this tear until it creates a new channel. The new channel in which blood can now flow is called the false lumen, and the artery is said to have dissected. An echocardiogram can be used to detect a false lumen with aortic dissection, and an endovascular stent can be used for its repair.