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Title: Mechanical Characteristics of Composite Knitted Stents

Abstract

We used metal wires and fibers to fabricate a composite knitted stent and then compare the mechanical characteristics of this stent with those of a pure metallic stent of the same construction in order to develop a stent that offers a comparable degree of expandability as metallic stents but can be used for highly curved lesions that cannot be treated using metallic stents. We fabricated two types of composite knitted stent (N-Z stents), using nitinol wire with a diameter of 0.12 mm and polypara-phenylene-benzobisoxazole (PBO) multifilament fiber (Zyron AS; Toyobo, Osaka, Japan). Stents were knitted into a cylindrical shape using the same textile pattern as a Strecker stent. Two loop lengths (L) of nitinol wire were used in the N-Z stents: L = 1.84 mm (N-Z stent L = 1.84) and L = 2.08 mm (N-Z stent L = 2.08). For the sake of comparison, we fabricated a metallic stent of nitinol using the same textile pattern (N-N stent L = 1.92). We applied a radial compression force diametrically to each stent and applied a bending force diametrically at the free end of a stent with one end fixed in order to evaluate the relationship between stent elasticity and loadmore » values. In addition, we macroscopically evaluated the generation of kinks when the stent was bent 180{sup o}. The radial compressive force when the stent diameter was reduced by 53% was 6.44 N in the case of N-Z stent L = 1.84, 6.14 N in the case of N-Z stent L = 2.08, and 4.96 N in the case of N-N stent L = 1.92 mm. The composite stent had a radial compressive force higher than that of a metallic stent. The restoring force to longitudinal direction at a 90{sup o} bending angle was 0.005 N for N-Z stent L = 1.84, 0.003 N for N-Z stent L = 2.08, and 0.034 N for N-N stent L = 1.92. The restoring force of the composite stent was significantly lower. Finally, the composite stent generated no definitive kinks at a bending angle of 180{sup o}, regardless of loop length. However, the N-N stent clearly produced kinks, causing blockage of the inner cavity. In conclusion, the use of a metal and fiber composite in the construction of a knitted stent ensures an expansion performance comparable to that of metallic stents, while providing better kink resistance.« less

Authors:
; ; ;  [1];  [2]; ;  [1]
  1. Kansai Medical University Hirakata Hospital, Department of Radiology (Japan)
  2. Kansai Medical University Takii Hospital, Department of Radiology (Japan)
Publication Date:
OSTI Identifier:
21429099
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cardiovascular and Interventional Radiology; Journal Volume: 32; Journal Issue: 5; Other Information: DOI: 10.1007/s00270-009-9622-7; Copyright (c) 2009 Springer Science+Business Media, LLC and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FIBERS; METALS; NICKEL ALLOYS; TITANIUM ALLOYS; TUBES; WIRES; ALLOYS; ELEMENTS; TRANSITION ELEMENT ALLOYS

Citation Formats

Tokuda, Takanori, E-mail: tkdtknr@gmail.com, Shomura, Yuzo, Tanigawa, Noboru, Kariya, Shuji, Komemushi, Atsushi, Kojima, Hiroyuki, and Sawada, Satoshi. Mechanical Characteristics of Composite Knitted Stents. United States: N. p., 2009. Web. doi:10.1007/S00270-009-9622-7.
Tokuda, Takanori, E-mail: tkdtknr@gmail.com, Shomura, Yuzo, Tanigawa, Noboru, Kariya, Shuji, Komemushi, Atsushi, Kojima, Hiroyuki, & Sawada, Satoshi. Mechanical Characteristics of Composite Knitted Stents. United States. doi:10.1007/S00270-009-9622-7.
Tokuda, Takanori, E-mail: tkdtknr@gmail.com, Shomura, Yuzo, Tanigawa, Noboru, Kariya, Shuji, Komemushi, Atsushi, Kojima, Hiroyuki, and Sawada, Satoshi. 2009. "Mechanical Characteristics of Composite Knitted Stents". United States. doi:10.1007/S00270-009-9622-7.
@article{osti_21429099,
title = {Mechanical Characteristics of Composite Knitted Stents},
author = {Tokuda, Takanori, E-mail: tkdtknr@gmail.com and Shomura, Yuzo and Tanigawa, Noboru and Kariya, Shuji and Komemushi, Atsushi and Kojima, Hiroyuki and Sawada, Satoshi},
abstractNote = {We used metal wires and fibers to fabricate a composite knitted stent and then compare the mechanical characteristics of this stent with those of a pure metallic stent of the same construction in order to develop a stent that offers a comparable degree of expandability as metallic stents but can be used for highly curved lesions that cannot be treated using metallic stents. We fabricated two types of composite knitted stent (N-Z stents), using nitinol wire with a diameter of 0.12 mm and polypara-phenylene-benzobisoxazole (PBO) multifilament fiber (Zyron AS; Toyobo, Osaka, Japan). Stents were knitted into a cylindrical shape using the same textile pattern as a Strecker stent. Two loop lengths (L) of nitinol wire were used in the N-Z stents: L = 1.84 mm (N-Z stent L = 1.84) and L = 2.08 mm (N-Z stent L = 2.08). For the sake of comparison, we fabricated a metallic stent of nitinol using the same textile pattern (N-N stent L = 1.92). We applied a radial compression force diametrically to each stent and applied a bending force diametrically at the free end of a stent with one end fixed in order to evaluate the relationship between stent elasticity and load values. In addition, we macroscopically evaluated the generation of kinks when the stent was bent 180{sup o}. The radial compressive force when the stent diameter was reduced by 53% was 6.44 N in the case of N-Z stent L = 1.84, 6.14 N in the case of N-Z stent L = 2.08, and 4.96 N in the case of N-N stent L = 1.92 mm. The composite stent had a radial compressive force higher than that of a metallic stent. The restoring force to longitudinal direction at a 90{sup o} bending angle was 0.005 N for N-Z stent L = 1.84, 0.003 N for N-Z stent L = 2.08, and 0.034 N for N-N stent L = 1.92. The restoring force of the composite stent was significantly lower. Finally, the composite stent generated no definitive kinks at a bending angle of 180{sup o}, regardless of loop length. However, the N-N stent clearly produced kinks, causing blockage of the inner cavity. In conclusion, the use of a metal and fiber composite in the construction of a knitted stent ensures an expansion performance comparable to that of metallic stents, while providing better kink resistance.},
doi = {10.1007/S00270-009-9622-7},
journal = {Cardiovascular and Interventional Radiology},
number = 5,
volume = 32,
place = {United States},
year = 2009,
month = 9
}
  • This paper presents the experimentally measured scattering distributions of different types of knitted fabrics on standard and defective sections. The best illumination and observation conditions for detecting flaws in knitted fabric are described. 17 refs., 11 figs.
  • Since nanocrystalline materials were first proposed by Gleiter et al. and as a result of their attractive properties, nanocrystalline materials of numerous compositions and structures have been prepared by different techniques among which mechanical attrition (MA) is an easy and effective method. In recent years synthesis of nanocrystalline composites, or nanophase composites have been studied extensively. The main methods used to synthesize nanophase composites by MA are mainly alloy power and ceramic powder together to form homogeneously distributed nanocrystalline metal/ceramic composites and milling element powders under atmosphere or medium to form metal/ceramic composites by reaction between elements and medium. Actuallymore » MA of immiscible systems may lead to the formation of a nanophase composite if two components can hardly dissolve into each other. In this paper mechanical alloying is studied for the immiscible Pb-Al and Fe-Cu systems.« less
  • Purpose: To assess selected balloon-expandable and self-expanding stents for radial force, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement.Methods: Force-strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radio-opacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of themore » stent on its delivery system to track over angles of 90 deg. and 60 deg. Results: The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity.Conclusion: There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed.« less