Stent

What are Stents?

In medicine, a stent is a man-made 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow access for surgery.

The illustration shows the placement of a stent in a coronary artery with plaque buildup. Figure A shows the deflated balloon catheter and closed stent inserted into the narrowed coronary artery. The inset image on figure A shows a cross-section of the artery with the inserted balloon catheter and closed stent. In figure B, the balloon is inflated, expanding the stent and compressing the plaque to restore the size of the artery. Figure C shows the stent-widened artery. The inset image on figure C shows a cross-section of the compressed plaque and stent-widened artery.

The origin of the word ''stent'' remains unsettled. The verb ''stenting'' was used for centuries for the process of stiffening garments (a usage long obsolete, per the ''Oxford English Dictionary'') and some believe this to be the origin. 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), which 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 support for facial tissues grew the eventual use of stent to open various bodily structures.

Worth noting though is that the first "stents" used in medical practice were initially called "Wallstents".

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Stent Types

Coronary arteries

The most widely known stent use is in the coronary arteries with a bare-metal stent, a drug-eluting stent or occasionally a covered stent.

Coronary stents are placed during a percutaneous coronary intervention procedure, also known as an angioplasty.

Urinary Tract

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. Indwelling times of 12 months or longer are indicated to hold ureters open, which are compressed by tumors in the neighbourhood of the ureter or by tumors of the ureter itself. In many cases these tumors are inoperable and the stents are used to ensure drainage of urine through the ureter. If drainage is compromised for longer periods, the kidney can be damaged. The main complications with ureteral stents are dislocation, infection and blockage by encrustation. Recently stents with coatings (e.g. heparin) were approved to reduce infection, encrustation and therefore stent exchanges.

Urethral / Prostatic stent

A urethral or Prostatic stent might be needed if a man is unable to urinate. Often this situation occurs when an enlarged prostate pushes against the urethra, blocking the flow of urine. The placement of a stent can open the obstruction, avoiding the collapse of the urethra. Urethral stent are now rarely used as a permanent treatment as they have grown to have a very bad reputation for failing and having to be removed

Vascular

Stents are used in a variety of vessels aside from the coronary arteries.

Peripheral vascular

Stents may be used as a component of peripheral artery angioplasty.

Stent Graft

A stent graft is a tubular device, which is composed of special fabric supported by a rigid structure, usually metal. The rigid structure is called a stent. An average stent on its own has no covering, and therefore is usually just a metal mesh. Although there are many types of stent, these stents are used mainly for vascular intervention.

The device is used primarily in endovascular surgery. Stent grafts are used to support weak points in arteries, such a point commonly known as an aneurysm. Stent grafts are most commonly used in the repair of an abdominal aortic aneurysm, in a procedure called an EVAR. The theory behind the procedure is that once in place inside the aorta, the stent graft acts as a false lumen for blood to travel through, instead of flowing into the aneurysm sack.

Other

  • CHD Stent
  • Oesophageal Stent
  • Duodenal Stent
  • Colonic Stent
  • Biliary Stent
  • Pancreatic Stent

This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Stent" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.