What is a stent and how is one used?
A stent is a wire metal mesh tube used to prop open an artery during angioplasty. The stent is collapsed to a small diameter and put over a balloon catheter. It’s then moved into the area of the blockage. When the balloon is inflated, the stent expands, locks in place and forms a scaffold. This holds the artery open. The stent stays in the artery permanently, holds it open, improves blood flow to the heart muscle and relieves symptoms (usually chest pain). Within a few weeks of the time the stent was placed, the inside lining of the artery (the endothelium) grows over the metal surface of the stent.
When are stents used?
Stents are used depending on certain features of the artery blockage. This includes the size of the artery and where the blockage is. Stenting is a fairly common procedure; in fact, over 70 percent of coronary angioplasty procedures also include stenting.
The purpose of endovascular stent surgery is to improve or restore the flow of blood and oxygen throughout the body, a process called coronary revascularization. Endovascular stent surgery is used most often to correct the narrowing in medium-sized and large arteries blocked by plaque. Stents have been used in coronary arteries, the carotid arteries in the neck, and renal (kidney) or biliary (gall bladder) arteries. They are rarely used for smaller arteries in the legs, for example, or other smaller vessels in the body.
Endovascular stenting is also the newest treatment for such emergency vascular events, as abdominal or thoracic (related to chest and lung area) aortic aneurysms. Aortic aneurysms are life-threatening bulges in the walls of the aorta, the largest artery in the body, usually the result of progressive atherosclerosis.
Stent surgery for emergency treatment of aortic aneurysm is called endovascular stent grafting or endovascular repair. Candidates for this treatment have either aortic aneurysms or other abnormal conditions of the aorta, such as an arteriovenous fistula (abnormal communication between an artery and a vein) or other kinds of aortic blockage.
Formerly these conditions were treated by highly invasive surgical procedures, with incisions that reached from the breastbone to the navel, to access the aorta, open it, and insert and attach a slender fabric-covered tube called a graft. During the less invasive endovascular stent surgery, a collapsed metal stent-graft (also called an endograft) is threaded through an artery beginning from a small incision in the groin and ending in the aorta. Threading is done through a tube-like delivery system lying in the vessel, which allows catheters and stents to move up and down during the procedure. A stent graft is similar to the stents used in coronary artery procedures, but has a ring of tiny hooks and barbs at each end that allow it to connect to the inner wall of the artery, replacing and repairing (grafting) the weakened area.
The surgeon guides the stentgraft into the aneurysm by using fluoroscopic x-ray imaging. When the stent graft is in place, its outer sheath is withdrawn and the stent graft is expanded. It will anchor itself to the inside of the artery wall with the hooks and barbs on each end. Some stent-graft systems also use balloons to push the hooks into the vessel wall. Because the procedure is minimally invasive, patients recover quickly and are usually able to eat the same day, walk on the second day, and go home in two to three days after the surgery.