A stent is an expandable metal tube that is used to treat weak arteries. These stents help in opening up arteries that are narrowed down by the accumulation of plaques. Implantation of the tube helps in reducing the constriction of blood flow in the affected region. The metal mesh is implanted during angioplasty. For larger arteries fabric stents called stent grafts are commonly used. During the procedure the stent is put over the balloon catheter. It is then moved to the narrowed region of the artery. As the balloon inflates, the stent expands and forms a scaffold in the area. This helps to keep the artery open for the procedure. The procedure of placing a stent is known as stenting and it is a minimally invasive procedure.
Some of the common conditions for which stenting is performed include:
- Coronary heart disease
- Renal artery stenosis
- Carotid artery disease
- Abdominal aortic aneurysm
- Peripheral artery disease
There are two main types of stents used in coronary arteries – bare-metal stents and drug-eluting stents (DES). Bare-metal stents are made of stainless steel while DES has metal struts coated with a growth inhibiting agent. This growth inhibiting agent escapes from DES in small amounts and prevents the proliferation of the cells. Stents are used in other blood vessels as well, when needed.
Special stents, called the ureteral stents, are used in the ureters when the ureteral opening is narrowed by kidney stones. It is also used when the ureters are blocked by tumors so as to endure the drainage of urine.
Other types of stents in use include:
- Esophageal stent
- Duodenal stent
- Colonic stent
- Biliary stent
- Pancreatic stent
There are some new generation stents that are under development or are approved in other countries, including:
- Bare-metal stents with coverings that delivers an anti-restenosis drug over a period of time
- Stents that are absorbed by the body after some time
- Stents with bio-engineered coating that makes a layer inside the blood vessel
- Diamond carbon-coated stents
- Antibody-coated stents
- Platinum-coated stainless steel stent
Stenting has some risks associated with the procedure. This includes the formation of blood clots in the stent, which may lead to complete blockage of the vessel. Those who have a stent in one of the arteries have to follow some simple precautions to prevent these complications. They are recommended to have blood-thinning drugs after stenting to prevent the blood clot formation. Small scar tissue may be formed in the stented area, leading to re-narrowing of the artery; this is referred to as restenosis and yet another stenting may be required to avoid any other issues.