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发帖数: 25265 | 1 http://en.wikipedia.org/wiki/Stent
Stent
From Wikipedia, the free encyclopedia
For people named Stent, see Stent (surname).
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
[hide] 1 Etymology
2 Stent types
3 See also
4 References
5 External links
Etymology
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.[1] 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".
Stent types
Type and description
Illustration
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.
An example of a coronary stent. This Taxus stent is labeled as a drug-
eluting stent.
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.
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.
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. Recent scientific breakthroughs have now meant using a
Prostatic stent is a viable method of dis-obstructing the prostate. Stents
can be temporary or permanent. Temporary stents can be placed in the
Urologist's office in a manner similar to placing a Foley catheter taking
less than 10 minutes and using only Lidocaine jelly. Clinical results[2]
show 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. Clinical results show occurrences of
migration, painful wearing and difficult removal.[3]
Prostatic/sphinchter stents can be used for draining the bladder in patient
with urethra obstruction, or nerve damages to the nerves controlling the
bladder. Stents could be placed in the prostate, across the outer and inner
sphinchter to achieve a good drainage of the bladder. The patient will need
to use diapers, incontinence pants/plastic pants, or a external collection
device (external catheter) to collect the urine.
Example of a stent / catheter used in the prostate to treat an enlarged
prostate and help obstructed urination
Stents are used in a variety of vessels aside from the coronary arteries.
Stents may be used as a component of peripheral artery angioplasty.
Stents for peripheral vessels
Esophageal stent
Endoscopic image of self-expanding metallic stent in an esophagus, which was
used to palliatively treat esophageal cancer.
Biliary stent, providing bile drainage
Endoscopic image of biliary stent seen protruding from ampulla of Vater at
the time of duodenoscopy
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.
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 other blood vessels in the body. A stent graft can be
used in either situation to create an open lumen and prevent blood from
flowing outside it.
Example of a Stent used in an Endovascular aneurysm repair
Other types of stents include Duodenal Stents, Colonic Stents, and
Pancreatic Stents
See also
Angioplasty
Bronchoscopy
Colonoscopy
Esophagogastroduodenoscopy
Grommet
Interventional Radiology
Restenosis
Bioresorbable stents |
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