Editing Stent (section)

==Stent types==
===By destination organ===
====Coronary stent====
[[File:Taxus stent FDA.jpg|thumb|right|upright=0.5|A balloon-expandable coronary stent on a balloon catheter]]
{{main article|Coronary stent}}
[[Coronary stent]]s are placed during a [[angioplasty|coronary angioplasty]]. The most common use for coronary stents is in the [[Coronary artery|coronary arteries]], into which a [[bare-metal stent]], a [[drug-eluting stent]], a bioabsorbable stent, <!-- abbreviation not explained a BVS or --> a [[Genous|dual-therapy stent]] (combination of both drug and bioengineered stent), or occasionally a covered stent is inserted.
<ref>{{Cite web|url=https://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/CerebralSpinalFluidCSFShuntSystems/default.htm|title=Cerebral Spinal Fluid (CSF) Shunt Systems|author=Center for Devices and Radiological Health|website=www.fda.gov|language=en|access-date=2017-09-25|archive-date=2017-11-04|archive-url=https://web.archive.org/web/20171104071530/https://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/CerebralSpinalFluidCSFShuntSystems/default.htm|url-status=dead}}</ref>

The majority of coronary stents used today are drug-eluting stents, which release medication to prevent complications such as blood clot formation and restenosis (re-narrowing). Stenting is performed through a procedure called percutaneous coronary intervention (PCI), where the cardiologist uses angiography and intravascular ultrasound to assess the blockage in the artery and determine the appropriate size and type of stent. The procedure is typically done in a catheterization clinic, and patients may need to stay overnight for observation. While stenting has been shown to reduce chest pain (angina) and improve survival rates after a heart attack, its effectiveness in stable angina patients has been debated {{citation needed|date=May 2025}}. 

Studies {{Citation needed|reason=Which studies? it would be useful to cite some examples|date=May 2025}} have found that most heart attacks occur due to plaque rupture rather than an obstructed artery that would benefit from a stent. Statins, along with PCI/stenting and anticoagulant therapies, are considered part of a broader treatment strategy. Some cardiologists believe that coronary stents are overused, but there is evidence of under-use in certain patient groups like the elderly. Ongoing research continues to explore new types of stents with biocompatible coatings or absorbable materials.

====Vascular stent====
[[File:Stent4 (fcm).jpg|thumb|right|upright=0.5|Compressed and expanded peripheral artery stents]]
Vascular stents are a common treatment for advanced [[peripheral artery disease|peripheral]] and [[cerebrovascular disease]]. Common sites treated with vascular stents include the [[carotid artery|carotid]], [[Common iliac artery|iliac]], and [[femoral artery|femoral]] arteries. Because of the external compression and mechanical forces subjected to these locations, flexible stent materials such as [[nitinol]] are used in many peripheral stents.<ref>{{cite journal | vauthors = Vogel TR, Shindelman LE, Nackman GB, Graham AM | title = Efficacious use of nitinol stents in the femoral and popliteal arteries | journal = Journal of Vascular Surgery | volume = 38 | issue = 6 | pages = 1178–1184 | date = December 2003 | pmid = 14681606 | doi = 10.1016/j.jvs.2003.09.011 | doi-access = free }}</ref>  

Vascular stents made of metals can lead to [[thrombosis]] at the site of treatment or to inflammation scarring. [[Drug-eluting stent]]s with pharmacologic agents or as drug delivery vehicles have been developed as an alternative to decrease the chances of restenosis.{{medical citation needed|date=November 2023}}

Because vascular stents are designed to expand inside a blocked artery to keep it open, allowing blood to flow freely, the mechanical properties of vascular stents are crucial for their function: they need to be highly elastic to allow for the expansion and contraction of the stent within the blood vessel, they also need to have high strength and fatigue resistance to withstand the constant physiological load of the arteries, they should have good biocompatibility to reduce the risk of thrombosis and vascular restenosis, and to minimize the body's rejection of the implant.<ref name="pmid34210099">{{cite journal|pmid=34210099|doi=10.3390/mi12070770|title=Structural Design of Vascular Stents: A Review |date=2021 |doi-access=free |last1=Pan |first1=Chen |last2=Han |first2=Yafeng |last3=Lu |first3=Jiping |journal=Micromachines |volume=12 |issue=7 |page=770 |pmc=8305143 }}</ref><ref name="pmid20717726">{{cite journal|pmid=20717726 |date=2010 |last1=Johnston |first1=C. R. |last2=Lee |first2=K. |last3=Flewitt |first3=J. |last4=Moore |first4=R. |last5=Dobson |first5=G. M. |last6=Thornton |first6=G. M. |title=The mechanical properties of endovascular stents: An in vitro assessment |journal=Cardiovascular Engineering (Dordrecht, Netherlands) |volume=10 |issue=3 |pages=128–135 |doi=10.1007/s10558-010-9097-9 |s2cid=28811127 }}</ref><ref name="pmid10656906">{{cite journal|pmid=10656906 |date=2000 |last1=Dyet |first1=J. F. |last2=Watts |first2=W. G. |last3=Ettles |first3=D. F. |last4=Nicholson |first4=A. A. |title=Mechanical properties of metallic stents: How do these properties influence the choice of stent for specific lesions? |journal=CardioVascular and Interventional Radiology |volume=23 |issue=1 |pages=47–54 |doi=10.1007/s002709910007 |s2cid=30277458 }}</ref>

Vascular stents are commonly used in angioplasty, a surgical procedure that opens blocked arteries and places a stent to keep the artery open. This is a common treatment for heart attacks and is also used in the prevention and treatment of strokes. Over 2 million people receive a stent each year for coronary artery disease alone. Vascular stents can also be used to prevent the rupture of aneurysms in the brain, aorta, or other blood vessels.<ref name="pmid35321023">{{cite journal|doi=10.3389/fbioe.2022.826807|pmid=35321023 |doi-access=free |title=Applying Principles of Regenerative Medicine to Vascular Stent Development |date=2022 |last1=Selvakumar |first1=Prakash Parthiban |last2=Rafuse |first2=Michael Scott |last3=Johnson |first3=Richard |last4=Tan |first4=Wei |journal=Frontiers in Bioengineering and Biotechnology |volume=10 |pmc=8936177 }}</ref><ref name="pmid29492633">{{cite journal|pmid=29492633|title=Physical Properties of Venous Stents: An Experimental Comparison|date=2018 |last1=Dabir |first1=D. |last2=Feisst |first2=A. |last3=Thomas |first3=D. |last4=Luetkens |first4=J. A. |last5=Meyer |first5=C. |last6=Kardulovic |first6=A. |last7=Menne |first7=M. |last8=Steinseifer |first8=U. |last9=Schild |first9=H. H. |author10=Kuetting DLR |journal=CardioVascular and Interventional Radiology |volume=41 |issue=6 |pages=942–950 |doi=10.1007/s00270-018-1916-1 |s2cid=3580960 }}</ref>

====Ureteric stent====
[[File:Abdominal Xray with uretal stent.jpg|thumb|right|upright=0.5|Example of a ureteral stent used to alleviate [[hydronephrosis]] of the kidney]]
{{main article|Ureteric stent}}
[[Ureteric 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 kidney caused by a kidney stone until a procedure to remove the stone can be performed. 

An ureteral stent it is typically inserted using a cystoscope, and one or both ends of the stent may be coiled to prevent movement. Ureteral stents are used for various purposes, such as temporary measures to prevent damage to a blocked kidney until a stone removal procedure can be performed, providing drainage for compressed ureters caused by tumors, and preventing spasms and collapse of the ureter after trauma during procedures like stone removal. The thread attached to some stents may cause irritation but allows for easy removal by pulling gently. 

Stents without threads require cystoscopy for removal. Recent developments have introduced magnetic retrieval systems that eliminate the need for invasive procedures like cystoscopy when removing the stent. The use of magnets enables simple extraction without anesthesia and can be done by primary care physicians or nurses rather than urologists. This method has shown high success rates across different patient groups including adults, children, and kidney transplant patients while reducing costs associated with operating room procedures.

====Prostatic stent====
[[File:Spanner insitu.jpg|thumb|right|upright=0.5|Example of a stent/catheter used in the prostate to treat an enlarged prostate and provide relief in cases of obstructed urination]]
{{main article|Prostatic stent}}
[[Prostatic stent]]s are placed from the [[bladder]] through the [[prostatic urethra|prostatic]] and [[penile urethra]] to allow drainage of the bladder through the [[penis]]. This is sometimes required in [[benign prostatic hyperplasia]].

A prostatic stent is used to keep the male urethra open and allow for the passage of urine in cases of prostatic obstruction and lower urinary tract symptoms (LUTS). There are two types of prostatic stents: temporary and permanent. Permanent stents, typically made of metal coils, are inserted into the urethra to apply constant gentle pressure and hold open sections that obstruct urine flow. They can be placed under anesthesia as an outpatient procedure but have disadvantages such as increased urination, limited incontinence, potential displacement or infection, and limitations on subsequent endoscopic surgical options. On the other hand, temporary stents can be easily inserted with topical anesthesia similar to a Foley catheter, and allow patients to retain volitional voiding. However, they may cause discomfort or increased urinary frequency.

In the US, there is one temporary prostatic stent that has received FDA approval called The Spanner. It maintains urine flow while allowing natural voluntary urination.<ref>{{cite journal | url=https://www.fda.gov/medical-devices/recently-approved-devices/spanner-temporary-prostatic-stent-p060010s013 | title=The Spanner Temporary Prostatic Stent - P060010/S013 | journal=FDA | date=28 November 2022 | access-date=21 November 2023 | archive-date=21 November 2023 | archive-url=https://web.archive.org/web/20231121145057/https://www.fda.gov/medical-devices/recently-approved-devices/spanner-temporary-prostatic-stent-p060010s013 | url-status=dead }}</ref> Research on permanent stents often focuses on metal coil designs that expand radially to hold open obstructed areas of the urethra. 

These permanent stents are used for conditions like benign prostatic hyperplasia (BPH), recurrent bulbar urethral stricture (RBUS), or detrusor external sphincter dyssynergia (DESD). The Urolume is currently the only FDA-approved permanent prostatic stent.<ref name="pmid33457695">{{cite journal|pmid=33457695 |date=2020 |last1=Banerjee |first1=I. |last2=Smith |first2=N. A. |last3=Katz |first3=J. E. |last4=Gokhale |first4=A. |last5=Shah |first5=R. |last6=Shah |first6=H. N. |title=Simultaneous Holmium Laser Enucleation of Prostate with Removal of the Permanent Prostatic Urethral Stent Using the High-Power Holmium Laser: Technique in Two Cases and Review of the Literature |journal=Journal of Endourology Case Reports |volume=6 |issue=4 |pages=438–441 |doi=10.1089/cren.2020.0158 |pmc=7803212 }}</ref>
{{clear}}
==== Colon and Esophageal stents ====
[[File:SEMS endo.jpg|thumb|right|upright=0.5|[[Esophagogastroduodenoscopy|Endoscopic]] image of a [[self-expanding metallic stent]] in an [[esophagus]], used to [[palliative care|palliatively]] treat [[esophageal cancer]] ]]
{{main article|Esophageal stent}}
Colon and [[esophageal stent|esophageal]] stents are a [[palliative care|palliative]] treatment for advanced [[colon cancer|colon]] and [[esophageal cancer]].

A colon stent is typically made of flexible metal mesh that can expand and hold open the blocked area, allowing for the passage of stool. Colon stents are used primarily as a palliative treatment for patients with advanced colorectal cancer who are not candidates for surgery. They help relieve symptoms such as abdominal pain, constipation, and bowel obstruction caused by tumors or strictures in the colon.

The placement of a colon stent involves endoscopic techniques similar to esophageal stenting. A thin tube called an endoscope is inserted into the rectum and guided through the colon to locate the blockage. Using fluoroscopy or endoscopic guidance, a guidewire is passed through the narrowed area and then removed after positioning it properly. The stent is then delivered over the guidewire and expanded to keep open the obstructed section of the colon. Complications associated with colon stents include perforation of the intestinal wall, migration or dislodgment of the stent, bleeding, infection at insertion site, or tissue overgrowth around it.<ref name="pmid33981755">{{cite journal|pmid=33981755 |date=2021 |last1=Belle |first1=S. |title=Endoscopic Decompression in Colonic Distension |journal=Visceral Medicine |volume=37 |issue=2 |pages=142–148 |doi=10.1159/000514799 |pmc=8077502 }}</ref>

Colon stenting provides several benefits including prompt relief from bowel obstruction symptoms without invasive surgery in many cases. It allows for faster recovery time compared to surgical interventions while providing palliative care for patients with advanced colorectal cancer by improving quality of life and enabling better nutritional intake. However, there are potential risks associated with complications such as migration or obstruction that may require additional procedures or interventions to address these issues effectively.<ref name="pmid35166883">{{cite journal|pmid=35166883 |date=2022 |last1=Kim |first1=G. H. |last2=Shin |first2=J. H. |last3=Zeng |first3=C. H. |last4=Park |first4=J. H. |title=Recent Updates in Gastrointestinal Stent Placement from the Esophagus to the Colon: A Radiological Perspective |journal=CardioVascular and Interventional Radiology |volume=45 |issue=4 |pages=425–437 |doi=10.1007/s00270-022-03067-5 |s2cid=246826137 }}</ref>

==== Pancreatic and biliary stents ====
[[File:Biliary stent endo.jpg|thumb|right|upright=0.5|Endoscopic image of a biliary stent seen protruding from the [[ampulla of Vater]] at the time of duodenoscopy]]
Pancreatic and biliary stents provide [[bile drainage|pancreatic and bile drainage]] from the [[gallbladder]], [[pancreas]], and [[bile duct]]s to the [[duodenum]] in conditions such as [[ascending cholangitis]] due to obstructing [[gallstone]]s.

Pancreatic and biliary stents can also be used to treat biliary/pancreatic leaks or to prevent post-ERCP pancreatitis.<ref name="pmid 23410693">{{cite journal|pmid=23410693 |date=2013 |author1=ASGE Technology Assessment Committee |last2=Pfau |first2=P. R. |last3=Pleskow |first3=D. K. |last4=Banerjee |first4=S. |last5=Barth |first5=B. A. |last6=Bhat |first6=Y. M. |last7=Desilets |first7=D. J. |last8=Gottlieb |first8=K. T. |last9=Maple |first9=J. T. |last10=Siddiqui |first10=U. D. |last11=Tokar |first11=J. L. |last12=Wang |first12=A. |last13=Song |first13=L. M. |last14=Rodriguez |first14=S. A. |title=Pancreatic and biliary stents |journal=Gastrointestinal Endoscopy |volume=77 |issue=3 |pages=319–327 |doi=10.1016/j.gie.2012.09.026 |doi-access=free }}</ref>

In the case of gallstone pancreatitis, a gallstone travels from the gallbladder and blocks the opening to the first part of the small intestine (duodenum). This causes a backup of fluid that can travel up both the bile duct and the pancreatic duct. Gallbladder stones can lead to obstruction of the biliary tree via which gallbladder and pancreas enzymes are secreted into the duodenum, causing emergency events such as acute cholecystitis or acute pancreatitis.<ref name="pmid 23410693"/>

In conditions such as ascending cholangitis due to obstructing gallstones, these stents play a crucial role. They help in maintaining the flow of bile and pancreatic juices from the gallbladder, pancreas, and bile ducts to the duodenum1. Biliary stents are often used during endoscopic retrograde cholangiopancreatography (ERCP) to treat blockages that narrow your bile or pancreatic ducts. In cases of malignant biliary obstruction, endoscopic stent placement is one of the treatment options to relieve the obstruction. Biliary drainage is considered effective, particularly in bile duct conditions that are diagnosed and treated early.<ref name="pmid 23410693"/>

==== Glaucoma drainage stent ====
[[Glaucoma]] drainage stents are recent developments and have been recently approved in some countries.<ref>{{Cite journal |last1=Chan |first1=Lilian |last2=Moster |first2=Marlene R. |last3=Bicket |first3=Amanda K. |last4=Sheybani |first4=Arsham |last5=Sarkisian |first5=Steven R. |last6=Samuelson |first6=Thomas W. |last7=Ahmed |first7=Iqbal Ike K. |last8=Miller-Ellis |first8=Eydie |last9=Smith |first9=Oluwatosin U. |last10=Cui |first10=Qi N. |date=October 2023 |title=New Devices in Glaucoma |journal=Ophthalmology and Therapy |volume=12 |issue=5 |pages=2381–2395 |doi=10.1007/s40123-023-00780-3 |issn=2193-8245 |pmid=37558818|pmc=10441989 }}</ref> They are used to reduce [[intraocular pressure]] by providing a drainage channel.

=== By properties or function ===
====Bare-metal stent====
[[File:Aneurysm endovascular.jpg|thumb|right|upright=0.5|[[Endovascular aneurysm repair]] using large stent grafts]]
{{main article|Bare-metal stent}}
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|bare metal stent]]. Covered stents are used in [[endovascular surgery|endovascular surgical]] procedures such as [[endovascular aneurysm repair]]. Stent grafts are also used to treat [[stenosis|stenoses]] in [[vascular graft]]s and [[fistula]]s used for [[Hemodialysis#Access|hemodialysis]].

==== Bioresorbable stent ====
{{main article|Bioresorbable stent}}
A bioresorbable stent is a tube-like device made from a material that can release a drug to prevent scar tissue growth. It is used to open and widen clogged heart arteries and then dissolves or is absorbed by the body. Unlike traditional metal stents, bioresorbable stents can restore normal vessel function, avoid long-term complications, and enable natural reconstruction of the arterial wall.

Metal-based bioresorbable scaffolds include iron, magnesium, zinc, and their alloys. Magnesium-based scaffolds have been approved for use in several countries around the world and show promising clinical results in delivering against the drawbacks of permanent metal stents. However, attention has been given to reducing the rate of magnesium corrosion through alloying and coating techniques.

Clinical research shows that resorbable scaffolds offer comparable efficacy and safety profiles to traditional drug-eluting stents (DES). The Magmaris resorbable magnesium scaffold has reported favorable safety outcomes similar to thin-strutted DES in patient populations. The Absorb naturally dissolving stent has also shown low rates of major adverse cardiac events when compared to DES. Imaging studies demonstrate that these naturally dissolving stents begin to dissolve between six months to two years after placement in the artery.

==== Drug-eluting stent ====
{{main article|Drug-eluting stent}}
Drug-eluting stents (DES) are specialized medical devices used to treat coronary artery disease and peripheral artery disease. They release a drug that inhibits cellular growth into the blocked or narrowed arteries, reducing the risk of blockages. DES are commonly placed using percutaneous coronary intervention (PCI), a minimally invasive procedure performed via catheter. These stents have shown clear advantages over older bare-metal stents, improving patient outcomes and quality of life for cardiac patients. With over 90% of stents used in PCI procedures being drug-eluting as of 2023, DES have become the standard choice for interventional cardiologists.

DES gradually release drugs that prevent restenosis and thrombosis within the treated arteries, addressing common complications associated with previous treatments. While risks such as clot formation and bleeding exist, studies have demonstrated superior efficacy compared to bare-metal stents in reducing major adverse cardiac events like heart attacks and repeat revascularization procedures. Long-term outcomes are still being studied due to their relatively recent introduction; however, DES have revolutionized the treatment of coronary artery disease by significantly improving patient outcomes and enhancing their quality of life.