Stent

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Stent
Blausen 0034 Angioplasty Stent 01.png
3D rendering of a stent in a coronary artery
MeSH D015607
MedlinePlus 002303

In medicine, a stent is a tube usually constructed of a metallic alloy or a polymer. It is inserted into the lumen (hollow space) of an anatomic vessel or duct to keep the passageway open. Stenting refers to the placement of a stent. The word "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.

Contents

A stent is different 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.

There are various types of stents used for different medical purposes. Coronary stents are commonly used in coronary angioplasty, with drug-eluting stents being the most common type. Vascular stents are used for peripheral and cerebrovascular disease, while ureteral stents ensure the patency of a ureter. Prostatic stents can be temporary or permanent and are used to treat conditions like benign prostatic hypertrophy. Colon and esophageal stents are palliative treatments for advanced colon and esophageal cancer. Pancreatic and biliary stents provide drainage from the gallbladder, pancreas, and bile ducts to the duodenum in conditions such as obstructing gallstones. There are also different types of bare-metal, drug-eluting, and bioresorbable stents available based on their properties.

The term "stent" originates from Charles Thomas Stent, an English dentist who made advances in denture-making techniques in the 19th century. The use of coronary stents began in 1986 by Jacques Puel and Ulrich Sigwart to prevent vessel closure during coronary surgery.

Stent types

By destination organ

Coronary stent

A balloon-expandable coronary stent on a balloon catheter Taxus stent FDA.jpg
A balloon-expandable coronary stent on a balloon catheter

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. [1]

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. Studies 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

Compressed and expanded peripheral artery stents Stent4 fcm.jpg
Compressed and expanded peripheral artery stents

Vascular stents are a common treatment for advanced peripheral and cerebrovascular disease. Common sites treated with vascular 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 many peripheral stents. [2]

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

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. [3] [4] [5]

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. [6] [7]

Ureteric stent

Example of a ureteral stent used to alleviate hydronephrosis of the kidney Abdominal Xray with uretal stent.jpg
Example of a ureteral stent used to alleviate hydronephrosis of the kidney

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

Example of a stent/catheter used in the prostate to treat an enlarged prostate and provide relief in cases of obstructed urination Spanner insitu.jpg
Example of a stent/catheter used in the prostate to treat an enlarged prostate and provide relief in cases of obstructed urination

Prostatic stents are placed 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.

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. [8] 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. [9]

Colon and Esophageal stents

Endoscopic image of a self-expanding metallic stent in an esophagus, used to palliatively treat esophageal cancer SEMS endo.jpg
Endoscopic image of a self-expanding metallic stent in an esophagus, used to palliatively treat esophageal cancer

Colon and esophageal stents are a palliative treatment for advanced 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. [10]

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. [11]

Pancreatic and biliary stents

Endoscopic image of a biliary stent seen protruding from the ampulla of Vater at the time of duodenoscopy Biliary stent endo.jpg
Endoscopic image of a biliary stent seen protruding from the ampulla of Vater at the time of duodenoscopy

Pancreatic and biliary stents provide pancreatic and bile drainage from the gallbladder, pancreas, and bile ducts to the duodenum in conditions such as ascending cholangitis due to obstructing gallstones.

Pancreatic and biliary stents can also be used to treat biliary/pancreatic leaks or to prevent post-ERCP pancreatitis. [12]

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. [12]

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. [12]

Glaucoma drainage stent

Glaucoma drainage stents are recent developments and have been recently approved in some countries. [13] They are used to reduce intraocular pressure by providing a drainage channel.

By properties or function

Bare-metal stent

Endovascular aneurysm repair using large stent grafts Aneurysm endovascular.jpg
Endovascular aneurysm repair using large stent grafts

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.

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

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.

Etymology

The current accepted origin of the word stent is that it derives from the name of an English dentist, Charles Thomas Stent (1807–1885), notable for his advances in the field of denture-making. [14] [15] He was born in Brighton, England, on October 17, 1807, 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. 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 Charles Stent, whom Esser employed to craft a form for facial reconstruction. The full account is described in the Journal of the History of Dentistry. [16] 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 body structures.

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[ who? ] 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 'to stretch', which in turn came from Latin extentus, the past participle of extendō 'to stretch out'.

The first (self-expanding) "stents" used in medical practice in 1986 by Ulrich Sigwart in Lausanne were initially called "Wallstents" after their inventor, Hans Wallstén. [17] [18] Julio Palmaz et al. created a balloon-expandable stent that is currently used. [19]

History

The first use of a coronary stent is typically attributed to Jacques Puel  [ fr ] and Ulrich Sigwart, who implanted a stent into a patient in Toulouse, France, in 1986. [14] That stent was used as a scaffold to prevent a 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 [20] ) and Richard Schatz implanted their similar stent into a patient in Germany.

Though several doctors have been credited with the creation of the stent, the first FDA-approved stent in the U.S. was created by Richard Schatz and coworkers. Named the Palmaz-Schatz (Johnson & Johnson), it was developed in 1987. [21]

To further reduce the incidence of restenosis, the drug-eluting stent was introduced in 2003. [22] Research has led to general stent design changes and improvements since that time. [23] Bioresorbable scaffolds have also entered the market, though a large-scale clinical trial showed higher acute risks compared to drug-eluding stents. As a result, the FDA issued an official warning for their use in 2013, and research on the design and performance optimisation of stents is ongoing. [24]

See also

Related Research Articles

<span class="mw-page-title-main">Angioplasty</span> Procedure to widen narrow arteries or veins

Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis. A deflated balloon attached to a catheter is passed over a guide-wire into the narrowed vessel and then inflated to a fixed size. The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow. A stent may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn. Angioplasty has come to include all manner of vascular interventions that are typically performed percutaneously.

<span class="mw-page-title-main">Bile duct</span> Type of organ

A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates. The bile duct is separated into three main parts the fundus, body, and neck which are superior, middle, and inferior respectively.

<span class="mw-page-title-main">Interventional radiology</span> Medical subspecialty

Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs both diagnostic and therapeutic procedures through very small incisions or body orifices. Diagnostic IR procedures are those intended to help make a diagnosis or guide further medical treatment, and include image-guided biopsy of a tumor or injection of an imaging contrast agent into a hollow structure, such as a blood vessel or a duct. By contrast, therapeutic IR procedures provide direct treatment—they include catheter-based medicine delivery, medical device placement, and angioplasty of narrowed structures.

<span class="mw-page-title-main">Restenosis</span> Recurrence of stenosis, a narrowing of a blood vessel

Restenosis is the recurrence of stenosis, a narrowing of a blood vessel, leading to restricted blood flow. Restenosis usually pertains to an artery or other large blood vessel that has become narrowed, received treatment to clear the blockage and subsequently become renarrowed. This is usually restenosis of an artery, or other blood vessel, or possibly a vessel within an organ.

<span class="mw-page-title-main">Endoscopic retrograde cholangiopancreatography</span> Use of endoscopy and fluoroscopy to treat and diagnose digestive issues.

Endoscopic retrograde cholangiopancreatography (ERCP) is a technique that combines the use of endoscopy and fluoroscopy to diagnose and treat certain problems of the biliary or pancreatic ductal systems. It is primarily performed by highly skilled and specialty trained gastroenterologists. Through the endoscope, the physician can see the inside of the stomach and duodenum, and inject a contrast medium into the ducts in the biliary tree and pancreas so they can be seen on radiographs.

<span class="mw-page-title-main">Common bile duct</span> Gastrointestinal duct

The bile duct is a part of the biliary tract. It is formed by the union of the common hepatic duct and cystic duct. It ends by uniting with the pancreatic duct to form the hepatopancreatic ampulla. It possesses its own sphincter to enable regulation of bile flow.

<span class="mw-page-title-main">Percutaneous coronary intervention</span> Medical techniques used to manage coronary occlusion

Percutaneous coronary intervention (PCI) is a minimally invasive non-surgical procedure used to treat narrowing of the coronary arteries of the heart found in coronary artery disease. The procedure is used to place and deploy coronary stents, a permanent wire-meshed tube, to open narrowed coronary arteries. PCI is considered 'non-surgical' as it uses a small hole in a peripheral artery (leg/arm) to gain access to the arterial system, an equivalent surgical procedure would involve the opening of the chest wall to gain access to the heart area. The term 'coronary angioplasty with stent' is synonymous with PCI. The procedure visualises the blood vessels via fluoroscopic imaging and contrast dyes. PCI is performed by an interventional cardiologists in a catheterization laboratory setting.

<span class="mw-page-title-main">Drug-eluting stent</span> Medical stent that releases drug

A drug-eluting stent (DES) is a thin tube that is used to treat narrowed arteries in medical procedures. It releases drugs to prevent the growth of scar tissue and reduce the risk of stent restenosis, which is the narrowing of the stented area of an artery after treatment. A drug-eluting stent is different from other types of stents because it has a coating that delivers medication directly to the arterial wall. A DES is often made of metal alloys and can be inserted into blocked or narrowed arteries through a catheter placed in a peripheral artery, such as in the arm or leg. DES is fully integrated with a catheter delivery system and is viewed as one integrated medical device.

<span class="mw-page-title-main">Ascending cholangitis</span> Medical condition

Ascending cholangitis, also known as acute cholangitis or simply cholangitis, is inflammation of the bile duct, usually caused by bacteria ascending from its junction with the duodenum. It tends to occur if the bile duct is already partially obstructed by gallstones.

<span class="mw-page-title-main">Self-expandable metallic stent</span>

A self-expandable metallic stent is a metallic tube, or stent that holds open a structure in the gastrointestinal tract to allow the passage of food, chyme, stool, or other secretions related to digestion. Surgeons insert SEMS by endoscopy, inserting a fibre optic camera—either through the mouth or colon—to reach an area of narrowing. As such, it is termed an endoprosthesis. SEMS can also be inserted using fluoroscopy where the surgeon uses an X-ray image to guide insertion, or as an adjunct to endoscopy.

<span class="mw-page-title-main">Percutaneous transhepatic cholangiography</span> Medical imaging of the biliary tract

Percutaneous transhepatic cholangiography, percutaneous hepatic cholangiogram (PTHC) is a radiological technique used to visualize the anatomy of the biliary tract. A contrast medium is injected into a bile duct in the liver, after which X-rays are taken. It allows access to the biliary tree in cases where endoscopic retrograde cholangiopancreatography has been unsuccessful. Initially reported in 1937, the procedure became popular in 1952.

The history of invasive and interventional cardiology is complex, with multiple groups working independently on similar technologies. Invasive and interventional cardiology is currently closely associated with cardiologists, though the development and most of its early research and procedures were performed by diagnostic and interventional radiologists.

<span class="mw-page-title-main">Coronary stent</span> Medical stent implanted into coronary arteries

A coronary stent is a tube-shaped device placed in the coronary arteries that supply blood to the heart, to keep the arteries open in patients suffering from coronary heart disease. The vast majority of stents used in modern interventional cardiology are drug-eluting stents (DES) It is used in a medical procedure called percutaneous coronary intervention (PCI). Coronary stents are divided into two broad types - drug-eluting and bare metal stents, as of 2023 drug-eluting stents were used in more than 90% of all PCI procedures. Stents reduce angina and have been shown to improve survival and decrease adverse events after a patient has suffered a heart attack - medically termed an acute myocardial infarction.

<span class="mw-page-title-main">Bare-metal stent</span>

A bare-metal stent is a stent made of thin, uncoated (bare) metal wire that has been formed into a mesh-like tube. The first stents licensed for use in cardiac arteries were bare metal – often 316L stainless steel. More recent "second generation" bare-metal stents have been made of cobalt chromium alloy. While plastic stents were first used to treat gastrointestinal conditions of the esophagus, gastroduodenum, biliary ducts, and colon, bare-metal stent advancements led to their use for these conditions starting in the 1990s.

Julio Palmaz is a doctor of vascular radiology at University of Texas Health Science Center at San Antonio. He studied at the National University of La Plata in Argentina, earning his medical degree in 1971. He then practiced vascular radiology at the San Martin University Hospital in La Plata before moving to the University of Texas Health and Science Center at San Antonio. He is known for inventing the balloon-expandable stent, for which he received a patent filed in 1985. It was recognized in Intellectual Property International Magazine as one of "Ten Patents that Changed the World" in the last century. His early stent research artifacts are now part of the medical collection of the Smithsonian Institution in Washington, DC. He continues to innovate on his initial designs, developing new endovascular devices.

<span class="mw-page-title-main">Bioresorbable stent</span> Medical stent that dissolves or is absorbed by the body

A bioresorbable stent is a tube-like device (stent) that is used to open and widen clogged heart arteries and then dissolves or is absorbed by the body. It is made from a material that can release a drug to prevent scar tissue growth. It can also restore normal vessel function and avoid long-term complications of metal stents.

<span class="mw-page-title-main">Sphincter of Oddi dysfunction</span> Medical condition

Sphincter of Oddi dysfunction refers to a group of functional disorders leading to abdominal pain due to dysfunction of the Sphincter of Oddi: functional biliary sphincter of Oddi and functional pancreatic sphincter of Oddi disorder. The sphincter of Oddi is a sphincter muscle, a circular band of muscle at the bottom of the biliary tree which controls the flow of pancreatic juices and bile into the second part of the duodenum. The pathogenesis of this condition is recognized to encompass stenosis or dyskinesia of the sphincter of Oddi ; consequently the terms biliary dyskinesia, papillary stenosis, and postcholecystectomy syndrome have all been used to describe this condition. Both stenosis and dyskinesia can obstruct flow through the sphincter of Oddi and can therefore cause retention of bile in the biliary tree and pancreatic juice in the pancreatic duct.

Cholecystostomy or (cholecystotomy) is a medical procedure used to drain the gallbladder through either a percutaneous or endoscopic approach. The procedure involves creating a stoma in the gallbladder, which can facilitate placement of a tube or stent for drainage, first performed by American surgeon, Dr. John Stough Bobbs, in 1867. It is sometimes used in cases of cholecystitis or other gallbladder disease where the person is ill, and there is a need to delay or defer cholecystectomy. The first endoscopic cholecystostomy was performed by Drs. Todd Baron and Mark Topazian in 2007 using ultrasound guidance to puncture the stomach wall and place a plastic biliary catheter for gallbladder drainage.

A dual therapy stent is a coronary artery stent that combines the technology of an antibody-coated stent and a drug-eluting stent. Currently, second-generation drug-eluting stents require long-term use of dual-antiplatelet therapy, which increases the risk of major bleeding occurrences in patients. Compared to drug-eluting stents, dual therapy stents have improved vessel regeneration and cell proliferation capabilities. As a result, dual therapy stents were developed to reduce the long-term need for dual-antiplatelet therapy.

<span class="mw-page-title-main">Biloma</span> Circumscribed abdominal collection of bile outside the biliary tree

A biloma is a circumscribed abdominal collection of bile outside the biliary tree. It occurs when there is excess bile in the abdominal cavity. It can occur during or after a bile leak. There is an increased chance of a person developing biloma after having a gallbladder removal surgery, known as laparoscopic cholecystectomy. This procedure can be complicated by biloma with incidence of 0.3–2%. Other causes are liver biopsy, abdominal trauma, and, rarely, spontaneous perforation. The formation of biloma does not occur frequently. Biliary fistulas are also caused by injury to the bile duct and can result in the formation of bile leaks. Biliary fistulas are abnormal communications between organs and the biliary tract. Once diagnosed, they usually require drainage. The term "biloma" was first coined in 1979 by Gould and Patel. They discovered it in a case with extrahepatic bile leakage. The cause of this was trauma to the upper right quadrant of the abdomen. Originally, biloma was described as an "encapsulated collection" of extrahepatic bile. Biloma is now described as extrabiliary collections of bile that can be either intrahepatic or extrahepatic. The most common cause of biloma is trauma to the liver. There are other causes such as abdominal surgery, endoscopic surgery and percutaneous catheter drainage. Injury and abdominal trauma can cause damage to the biliary tree. The biliary tree is a system of vessels that direct secreations from the liver, gallbladder, and pancreas through a series of ducts into the duodenum. This can result in a bile leak which is a common cause of the formation of biloma. It is possible for biloma to be associated with mortality, though it is not common. Bile leaks occur in about one percent of causes.

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  14. 1 2 Roguin A (April 2011). "Stent: the man and word behind the coronary metal prosthesis". Circulation: Cardiovascular Interventions. 4 (2): 206–209. doi: 10.1161/CIRCINTERVENTIONS.110.960872 . PMID   21505167.
  15. ↑ "stent" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
  16. ↑ Ring ME (July 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.
  17. ↑ Rorsman B. "His invention saves millions of lives". Chalmers University of Technology. Retrieved 25 July 2017.
  18. ↑ Bilardo C. "Hans Wallsten, inventor of the stent". Invivo Magazine. Retrieved 28 September 2016.
  19. ↑ Palmaz JC, Sibbitt RR, Reuter SR, Tio FO, Rice WJ (July 1985). "Expandable intraluminal graft: a preliminary study. Work in progress". Radiology. 156 (1): 73–77. doi:10.1148/radiology.156.1.3159043. PMID   3159043.
  20. ↑ "Guide to the Julio Palmaz Papers" . Retrieved 2018-08-24.
  21. ↑ Garg S, Serruys PW (August 2010). "Coronary stents: current status". Journal of the American College of Cardiology. 56 (10 Suppl): S1-42. doi: 10.1016/j.jacc.2010.06.007 . PMID   20797502.
  22. ↑ Puranik AS, Dawson ER, Peppas NA (January 2013). "Recent advances in drug eluting stents". International Journal of Pharmaceutics. 441 (1–2): 665–679. doi:10.1016/j.ijpharm.2012.10.029. PMC   3567608 . PMID   23117022.
  23. ↑ Beier S, Ormiston J, Webster M, Cater J, Norris S, Medrano-Gracia P, et al. (February 2016). "Hemodynamics in Idealized Stented Coronary Arteries: Important Stent Design Considerations". Annals of Biomedical Engineering. 44 (2): 315–329. doi:10.1007/s10439-015-1387-3. PMC   4764643 . PMID   26178872.
  24. ↑ Gharleghi R, Wright H, Luvio V, Jepson N, Luo Z, Senthurnathan A, et al. (August 2021). "A multi-objective optimization of stent geometries". Journal of Biomechanics. 125: 110575. doi:10.1016/j.jbiomech.2021.110575. PMID   34186293. S2CID   235685498.
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