stent

(stĕnt)

1. A device used to support a bodily orifice or cavity during skin grafting or to immobilize a skin graft following placement.
2. A slender thread, rod, or catheter inserted into a tubular structure, such as a blood vessel, to provide support during or after anastomosis.

[After Charles R. Stent (1845-1901), English dentist.]

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Key Terms: Endoscope, Esophagus.

Definition

Stenting is a procedure in which a cylindrical structure (stent) is placed into a hollow tubular organ to provide artificial support and maintain the patency of the opening. Although it is most often used for cardiovascular functioning, it is also utilized to manage obstructions in cancer patients.

Purpose

Stents are used in cancer patients to relieve obstructions due to:

• direct blockages within the tube (or lumen) due to cancer growth
• narrowing of the lumen from tumor growth outside pressing on the tube and narrowing the lumen
• occasionally from the build up of scar tissue (fibrosis) from radiation therapy

Tumors most likely to cause obstruction requiring stent placement include esophageal cancer, bronchogenic carcinoma, pancreatic cancer, cancers of the bile duct, and occasionally colorectal carcinomas.

Precautions

Every patient should be viewed individually with special consideration given to the patient's present status. Generally, surgical procedures are for the correction of a problem; but in many cancer cases, relief of symptoms is the only therapeutic option. Since it is extremely difficult to remove or reposition these stents after they are placed, the degree of relief to be offered by its insertion should be significant. The physician and the patient should discuss all alternatives and come to a mutual decision.

Description

Endoscopic retrograde cholangiopancreatography (ERCP) is the name of the procedure utilized to place most stents for pancreatic and biliary tumors. The ERCP is a flexible endoscope, which can be directed and moved around the many bends in the upper gastrointestinal tract. The newer video endoscopes have a tiny, optically sensitive computer chip at the end which transmits electronic signals up the scope to a computer that displays an image on a large video screen. The scope has an open channel that permits other instruments to be passed through it to perform biopsies, inject solutions, or place stents. Since ERCP uses x-ray films, the procedure takes place in an x-ray area. Initially the throat is anesthetized with a spray solution and the patient is also usually mildly sedated. The endoscope is inserted into the upper esophagus and a thin tube is inserted through it to the main bile duct entering the intestinal area. Dye is injected into the bile duct and/or the pancreatic duct and x-ray films are taken. The patient usually lies on the left side and then turns onto the stomach to allow complete visualization of the ducts. The patient is able to breathe easily throughout the exam and rarely gags. Any gallstones found may be removed or if the duct has become narrowed, an incision can be made using electrocautery (electrical heat) to relieve the blockage. It is also possible to widen narrowed ducts by placing stents in these areas to keep them open. The patient is taken to recovery following the procedure, which takes 20–40 minutes.

Other endoscopes are used to place stents elsewhere in the body. For example, an esophagoscope is used to place stents in cases of esophageal cancer, a broncho-scope is used for procedures involving endobronchial obstructions, and a colonoscope is used in cases of colorectal obstructions.

Preparation

The patient is instructed not to eat or drink anything for eight hours prior to the procedure. Some physicians may request that no asprin be taken for a certain time period prior to the procedure to prevent excessive bleeding.

Aftercare

The patient may go home after the procedure or may spend one or two nights in the hospital. Antibiotics may be given especially if there has been long-standing biliary obstruction. Dietary restrictions are common after esophageal and colorectal stenting.

Risks

The most serious risk associated with the placement of a stent is the risk of perforation. If a tear is made, leakage with life-threatening infection may occur. Migration or recurrent obstruction may necessitate repeat stenting if possible. Occasionally bleeding may occur.

Normal Results

Relief of the obstruction with resumption of the ability to eat, breathe, normally clear fluids from the liver or pancreas, or allow normal passage of stool is the desired result of this procedure.

Questions to Ask the Doctor

• Am I a good candidate for this procedure?
• Do I have any contraindications that should be considered before having the procedure?
• Will I experience any improvement in my quality of life?
• What are the advantages and disadvantages of the procedure?
• Does the physician performing the procedure do this often or only occasionally?

Abnormal Results

A sudden change in the degree of pain and/or fever that persists as well as any unusual changes should be communicated immediately to a physician.

Resources

Books

Dolmath, Bart L., and Ulrich Blum, editors. Stent-Grafts: Current Clinical Practice. New York: Thieme, 2000.

Other

American Cancer Society, P.O. Box 102454, Atlanta, GA 30368-2454. .

American Society of Clinical Oncology. 1900 Duke Street, Suite 200, Alexandria, VA 22314. Phone: 703-299-0150. .

Jackson Gastroenterology. .

National Digestive Diseases Information Clearinghouse. ERCP (Endoscopic Retrograde Cholangiopancreatography)..

—Linda K. Bennington, C.N.S., M.S.N.

A mold for keeping a skin graft in place, made of Stent's mass or some acrylic or dental compound; by extension, a device or mold of a suitable material used to hold a skin graft in place or to provide support for tubular structures that are being anastomosed. Also used in vascular and bile duct surgery, and repair of laryngeal, tracheal, nasal trauma and stenosis.

1. a device used to hold a skin graft placed to maintain a body orifice, cavity, or space. An acrylic resin appliance used as a positioning guide or support. 2. an appliance that maintains tissue (for example, to maintain a skin transplant in a predetermined position).

For people named Stent, see Stent (surname).

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2011)

Stent
Intervention
MeSH	D015607

In the technical vocabulary of medicine, a stent is an artificial '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.

Contents 1 Etymology 2 Stent types 3 See also 4 References 5 External links

Etymology

The origin of the word "stent" remains unsettled. 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.^[1] 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. It is worth noting that the first "stents" used in medical practice were initially called "Wallstents". In 1985, the Argentine doctor, Palmaz et al, create the self-expanding stent that is used until today.^[2]

Stent types

Type and description	Illustration
The most common use for stents is in coronary arteries, into which a bare-metal stent, a drug-eluting stent, or occasionally a covered stent is inserted. Coronary stents are placed during a percutaneous coronary intervention procedure, also known as an angioplasty.	An example of a coronary stent. This version, known as a Taxus stent, has a drug-eluting function
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 open ureters which have been 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) have been approved to reduce infection, encrustation and therefore the frequency of stent replacement.	Example of a uretal stent used to alleviate hydronephrosis of the kidney
A urethral or prostatic stent might be needed if a man is unable to urinate. This situation often occurs when an enlarged prostate pushes against the urethra, blocking the flow of urine. The placement of a stent can open the obstruction. Recent scientific breakthroughs have confirmed the use of a prostatic stent as a viable method of dis-obstructing the prostate. Stents can be temporary or permanent. Temporary stents can be placed in a urologist's office in a manner similar to placing a Foley catheter, requiring less than 10 minutes and using only lidocaine jelly as a local anesthetic. Clinical results[3] show that the temporary stent is effective and well tolerated. Permanent stents are mostly placed on an outpatient basis under local or spinal anesthesia and usually take about 30 minutes to insert. Clinical results show occurrences of migration, painful wearing, and difficult removal.[4] Prostatic/sphincter stents can be used for draining the bladder in patients with urethra obstruction or damage to the nerves controlling the bladder. Stents can be placed in the prostate, across the outer and inner sphincter, to achieve good drainage of the bladder. The patient requires diapers, incontinence pants/plastic pants, or an external collection device (external catheter) to collect the urine.	Example of a stent / catheter used in the prostate to treat an enlarged prostate and provide relief in cases of obstructed urination
Stents are used in a variety of blood vessels aside from coronary arteries. Stents may be used as a component of peripheral artery angioplasty.	Stents for peripheral vessels
Esophageal stent	Endoscopic image of a self-expanding metallic stent in an esophagus, used to palliatively treat esophageal cancer
Biliary stent, providing bile drainage	Endoscopic image of a biliary stent seen protruding from the ampulla of Vater at the time of duodenoscopy
A stent graft is a tubular device composed of special fabric supported by a rigid structure, the stent, which is usually metal. An average stent on its own has no covering, and is usually just a metal mesh. Although there are many types of stents, these stents are used mainly for vascular interventions. The device is used primarily in endovascular surgery. Stent grafts support weak points in arteries; such a point is commonly known as an aneurysm. Stent grafts are most commonly used to repair 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 through which blood can travel, instead of flowing into the aneurysm sack. Stent grafts are also commonly placed within grafts and fistulas used for dialysis. These accesses can become obstructed over time, or develop aneurysms similar to those in other blood vessels. A stent graft can be used in either situation to create an open lumen and prevent blood from flowing around it.	Example of a stent used in an endovascular aneurysm repair
Other types are duodenal stents, colonic stents, and pancreatic stents, the designations referring to the location of their placement.

See also

• Angioplasty
• Bronchoscopy
• Colonoscopy
• Esophagogastroduodenoscopy
• Grommet
• Interventional radiology
• Restenosis
• Bioresorbable stents

References

1. ^ 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. http://www.fauchard.org/publications/history/49_2_july01/stent49_2.htm. 
2. ^ Palmaz JC, Sibbitt RR, Reuter SR, Tio FO, Rice WJ. Expandable intraluminal graft: a preliminary study. Work in progress. Radiology. 1985 Jul;156(1):73–77.[PubMed]
3. ^ Dineen MK, Shore ND, Lumerman JH, Saslawsky MJ, Corica AP (May 2008). "Use of a temporary prostatic stent after transurethral microwave thermotherapy reduced voiding symptoms and bother without exacerbating irritative symptoms". Urology 71 (5): 873–7. doi:10.1016/j.urology.2007.12.015. PMID 18374395. 
4. ^ Kural AR, Tüfek I, Akpinar H, Gürtuğ A (November 2001). "Removal of urolume endoprosthesis using holmium:YAG laser". J. Endourol. 15 (9): 947–8. doi:10.1089/089277901753284198. PMID 11769852. 

External links

Wikimedia Commons has media related to: Stent

• Coronary Stent
• Drug-Eluting Stents — Angioplasty.Org
• Cardiovascular and Interventional Radiological Society of Europe
• The Cardiovascular Forum
• Stent for Life Initiative

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