Clin Endosc.  2016 Mar;49(2):108-112. 10.5946/ce.2016.029.

Basic Knowledge about Metal Stent Development

• Jeong S

• KMID: 2165033
• DOI: http://doi.org/10.5946/ce.2016.029

Abstract

Biliary self-expandable metal stents (SEMS), a group of non-vascular stents, have been used in the palliative management of biliary obstruction around the world. However, there are still unmet needs in the clinical application of biliary SEMS. Comprehensive understanding of the SEMS is required to resolve the drawbacks and difficulties of metal stent development. The basic structure of SEMS, including the materials and knitting methods of metal wires, covering materials, and radiopaque markers, are discussed in this review. What we know about the physical and mechanical properties of the SEMS is very important. With an understanding of the basic knowledge of metal stents, hurdles such as stent occlusion, migration, and kinking can be overcome to develop more ideal SEMS.

Keyword

Self expandable metallic stents; Biliary tract; Membranes

MeSH Terms

Biliary Tract
Membranes
Stents*

Figure

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  Fig. 1. Various basic structures of metal stents by wire-weaving method. (A) Wire crossover structures. (B) A laser-cut structure. Courtesy of M.I. Tech Co., Boston Scientific Co., Sewoon Medical Co. Ltd., and Cook Medical.

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  Fig. 2. Cell size of the self-expandable metal stent, which is controlled by the wire weaving method. (A) Large cells. (B) Small cells. Courtesy of M.I. Tech Co. and Sewoon Medical Co. Ltd.

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  Fig. 3. Cracks in the covering membrane in the basic structure of the stent under long-term exposure to bile juice. (A) Scanning electron microscopy image. (B) Gross finding. Courtesy of S&G BioTech Inc.

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  Fig. 4. Three to four platinum-wired radiopaque markers on both ends and in the center of the stents. Courtesy of Sewoon Medical Co. Ltd.

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  Fig. 5. Anti-reflux valve stent. Courtesy of S&G BioTech Inc.

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  Fig. 6. Double-layered, uncovered structure of self-expandable metal stent. Courtesy of S&G BioTech Inc. and Taewoong Medical Co. Ltd.

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  Fig. 7. Covered self-expandable metal stent with anti-migration flaps; the upper end is fitted with four flaps that reduce the risk of migration. Courtesy of M.I. Tech Co.

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  Fig. 8. Covered self-expandable metal stent that have different segmental radial forces created by different sizes of cells over the whole length of the stent. Courtesy of Taewoong Medical Co. Ltd.

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