Gastrointestinal and biliary stents

Abstract

Advances in stent design have led to a substantial increase in the use of stents for a variety of malignant and benign strictures in the gastrointestinal tract and biliary system. Whereas early stents were mostly composed of plastic, the majority of contemporary stents are self-expanding metal stents that are composed of either nitinol or stainless steel. These stents are able to exert an adequate expansile force and, at the same time, are highly flexible and biocompatible. Covered stents have been introduced to minimize tumor ingrowth through the metal mesh but are associated with higher rates for spontaneous migration. This has led to the development of covered stents with uncovered ends and stents with both covered and uncovered layers. Drug-eluting and biodegradable stents are also likely to become available in the near future. Although stents appear to be the preferred form of palliation for some patients with advanced cancer, many patients will benefit from a multidisciplinary approach that usually includes surgeons and oncologists.

Physical Properties of Covered Stent in Gastric Acid Environment: In Vitro Study

“…1 Its application has recently included benign strictures caused by complications of peptic ulcer, reflux esophagitis, the sur-폴리머, 제38권 제3호, 2014년 gery of the GI tract, and the ingestion of the corrosive drugs. 2 Plastic stents were initially used in this procedure but were later replaced by self-expandable metal stents (SEMSs) in the late 1980s, after being proven to have a superior clinical efficacy, with its ease in insertion and positioning and low risk of tissue damage during insertion.…”

“…SEMSs are available in two forms, depending on its covering: membrane covered and membrane uncovered. 1 Membrane-uncovered stents have the advantage of good adhesion and easy maneuvering, although it also presents the risk of tumor ingrowth within the stent, which may then lead to stent occlusion. Membrane covered stents were developed to address these drawbacks and are replacing uncovered stent.…”

Diagnostic and Therapeutic Endoscopy in the Biliary Tract and Pancreas

“…Because of this, stents are usually changed electively at intervals of about 3 months in those patients who require stenting for prolonged periods. Self-expanding metal stents (Figure 5d) are now widely used for palliation in patients with malignant obstructive jaundice (Chun et al, 2010). These stents expand to a diameter of approximately 30F (10 mm) and usually remain patent for 6-9 months.…”

An Update to Hepatobiliary Stents

“…15,17 They are composed of metal alloys, such as platinol (platinum core with nitinol encasement), nitinol (combination of nickel and titanium), or stainless steel. 15,18 Although nitinol is the metal of choice because of its ability to conform to the curved lumen, no one material has shown superiority. 18,19 Metal stents are cylindrical in shape and have interwoven alloy wires to create enough radial force around the duct stricture to prevent collapsibility.…”

“…15,18 Although nitinol is the metal of choice because of its ability to conform to the curved lumen, no one material has shown superiority. 18,19 Metal stents are cylindrical in shape and have interwoven alloy wires to create enough radial force around the duct stricture to prevent collapsibility. 18 The length of available SEMS range from 4 to 12 cm, and fully expanded diameters reach 6 to 10 mm.…”