Mechanical Characteristics of Composite Knitted Stents

Journal Article · Tue Sep 15 04:00:00 EDT 2009 · Cardiovascular and Interventional Radiology

DOI:https://doi.org/10.1007/S00270-009-9622-7· OSTI ID:21429099

Tokuda, Takanori; Shomura, Yuzo; Tanigawa, Noboru; Kariya, Shuji ^[1]; Komemushi, Atsushi ^[2]; Kojima, Hiroyuki; Sawada, Satoshi ^[1]

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1. Kansai Medical University Hirakata Hospital, Department of Radiology (Japan)
2. Kansai Medical University Takii Hospital, Department of Radiology (Japan)

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.

• OSTI ID: 21429099
• Journal Information: Cardiovascular and Interventional Radiology, Journal Name: Cardiovascular and Interventional Radiology Journal Issue: 5 Vol. 32; ISSN 0174-1551; ISSN CAIRDG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
ELEMENTS
FIBERS
METALS
NICKEL ALLOYS
TITANIUM ALLOYS
TRANSITION ELEMENT ALLOYS
TUBES
WIRES