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In medicine, a stent is a metal or plastic tube inserted into the lumen of an anatomic vessel or duct to keep the passageway open, and stenting is the placement of a stent. There is a wide variety of stents used for different purposes, from expandable coronary, vascular and biliary stents, to simple plastic stents used to allow the flow of urine between kidney and bladder. Stent is also used as a verb to describe the placement of such a device, particularly when a disease such as atherosclerosis has pathologically narrowed a structure such as an artery.
3D rendering of a stent in a coronary artery
A stent should be differentiated from a shunt. A shunt is a tube that connects two previously unconnected parts of the body to allow fluid to flow between them. Stents and shunts can be made of similar materials, but perform two different tasks.
|Type and description||Illustration|
|Coronary stents are placed during a coronary angioplasty. The most common use for coronary stents is in the coronary arteries, into which a bare-metal stent, a drug-eluting stent, a bioabsorbable stent, a dual-therapy stent (combination of both drug and bioengineered stent), or occasionally a covered stent is inserted.|
|Vascular stents are commonly placed as part of peripheral artery angioplasty. Common sites treated with peripheral artery stents include the carotid, iliac, and femoral arteries. Because of the external compression and mechanical forces subjected to these locations, flexible stent materials such as nitinol are used in a majority of peripheral stent placements.|
|A stent graft or covered stent is type of vascular stent with a fabric coating that creates a contained tube but is expandable like a bare metal stent. Covered stents are used in endovascular surgical procedures such as endovascular aneurysm repair. Stent grafts are also used to treat stenoses in vascular grafts and fistulas used for hemodialysis.|
|Ureteral stents are used to ensure the patency of a ureter, which may be compromised, for example, by a kidney stone. This method is sometimes used as a temporary measure to prevent damage to a blocked kidney until a procedure to remove the stone can be performed.|
|Prostatic stents are places from the bladder through the prostatic and penile urethra to allow drainage of the bladder through the penis. This is sometimes required in benign prostatic hypertrophy.|
|Esophageal stents are a palliative treatment for advanced esophageal cancer.|
|Biliary stents provide bile drainage from the gallbladder, pancreas and bile ducts to the duodenum in conditions such as ascending cholangitis due to obstructing gallstones.|
|Glaucoma drainage stents are recent developments and are awaiting approval in some countries. They are used to reduce intraocular pressure by providing a drainage channel.|
|Other types are duodenal stents, colonic stents, and pancreatic stents, the designations referring to the location of their placement.|
As Ariel Roguin describes in his paper "Stent: The Man and Word Behind the Coronary Metal Prosthesis", the current acceptable origin of the word stent is that it derives from the name of a dentist. Charles Thomas Stent, notable for his advances in the field of denture-making. He was born in Brighton, England, on October 17, 1807. He was a dentist in London and is most famous for improving and modifying the denture base of the gutta-percha, creating the Stent's compounding that made it practical as a material for dental impressions.
The verb form "stenting" was used for centuries to describe the process of stiffening garments (a usage long obsolete, per the Oxford English Dictionary) and some believe this to be the origin. According to the Merriam Webster Third New International Dictionary, the noun evolved from the Middle English verb stenten, shortened from extenten, meaning to stretch, which in turn came from Latin extentus, past participle of extendere, to stretch out. Others attribute the noun "stent" to Jan F. Esser, a Dutch plastic surgeon who in 1916 used the word to describe a dental impression compound invented in 1856 by the English dentist Charles Stent (1807–1885), whom Esser employed to craft a form for facial reconstruction. The full account is described in the Journal of the History of Dentistry. According to the author, from the use of Stent's compound as a support for facial tissues evolved the use of a stent to hold open various bodily structures.
The first (self expanding) "stents" used in medical practice in 1986 by Ulrich Sigwart in Lausanne were initially called "Wallstents" after its inventor Hans Wallsten. Julio Palmaz et al. created a balloon expandable stent that is currently used.
The first use of a coronary stent is typically attributed to Jacques Puel and Ulrich Sigwart when they implanted a stent into a patient in Toulouse, France in 1986. It was used as a scaffold to prevent the vessel from closing and to avoid restenosis in coronary surgery—a condition where scar tissue grows within the stent and interferes with vascular flow. Shortly thereafter in 1987, Julio Palmaz (known for patenting a balloon-expandable stent) and Richard Schatz implanted their similar stent into a patient in Germany. The use of these bare-metal stents helped reduce the incidence of restenosis from 30–40% in coronary surgery to 20–30%.
Though many doctors have created the stent, the first FDA approved stent was invented by Cesare Gianturco and Gary S. Roubin.
To further reduce the incidence of restenosis, drug-eluting stents (DES) were introduced[when?] which consisted of stents coated in anti proliferative agents. Animal studies and later clinical trials showed a reduction in restenosis to approximately 5%.
- Vogel, T; Shindelman, L.; Nackman, G.; Graham, A. (2003). "Efficacious Use of Nitinol Stents in the Femoral and Popliteal Arteries.". Journal of Vascular Surgery. 38 (6): 1178–1183. doi:10.1016/j.jvs.2003.09.011.
- Ring, Malvin (2001). "How a Dentist's Name Became a Synonym for a Life-saving Device: The Story of Dr. Charles Stent". Journal of the History of Dentistry. 49 (2): 77–80. PMID 11484317. Retrieved 27 January 2015.
- Céline Bilardo. "Hans Wallsten, inventor of the stent". Invivo Magazine. Retrieved 28 September 2016.
- Palmaz JC, Sibbitt RR, Reuter SR, Tio FO, Rice WJ (Jul 1985). "Expandable intraluminal graft: a preliminary study. Work in progress". Radiology. 156 (1): 73–77. PMID 3159043. doi:10.1148/radiology.156.1.3159043.
- Roguin, Ariel (2011). "Historical Perspectives in Cardiology". Circulation: Cardiovascular Interventsions. 4: 206–209. doi:10.1161/CIRCINTERVENTIONS.110.960872. Retrieved 6 April 2015.