Volume 80A, Issue 4 pp. 861-873

Stability of passivated 316L stainless steel oxide films for cardiovascular stents

Chun-Che Shih

Corresponding Author

Chun-Che Shih

Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei 112, Taiwan

Division of Cardiovascular Surgery, Taipei Veterans General Hospital, Taipei 112, Taiwan

Cardiovascular Research Center, National Yang-Ming University, Taipei 112, Taiwan

Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei 112, TaiwanSearch for more papers by this author
Chun-Ming Shih

Chun-Ming Shih

School of Medicine, Taipei Medical University, Taipei 110, Taiwan

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Kuang-Yi Chou

Kuang-Yi Chou

Center of General Education, National Taipei College of Nursing, Taipei 112, Taiwan

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Shing-Jong Lin

Shing-Jong Lin

Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei 112, Taiwan

Center of General Education, National Taipei College of Nursing, Taipei 112, Taiwan

Division of Cardiology, Taipei Veterans General Hospital, Taipei 112, Taiwan

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Yea-Yang Su

Yea-Yang Su

Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei 112, Taiwan

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First published: 27 October 2006
Citations: 17

Abstract

Passivated 316L stainless steel is used extensively in cardiovascular stents. The degree of chloride ion attack might increase as the oxide film on the implant degrades from exposure to physiological fluid. Stability of 316L stainless steel stent is a function of the concentration of hydrated and hydrolyated oxide concentration inside the passivated film. A high concentration of hydrated and hydrolyated oxide inside the passivated oxide film is required to maintain the integrity of the passivated oxide film, reduce the chance of chloride ion attack, and prevent any possible leaching of positively charged ions into the surrounding tissue that accelerate the inflammatory process. Leaching of metallic ions from corroded implant surface into surrounding tissue was confirmed by the X-ray mapping technique. The degree of thrombi weight percentage [Wao: (2.1 ± 0.9)%; Wep: (12.5 ± 4.9)%, p < 0.01] between the amorphous oxide (AO) and the electropolishing (EP) treatment groups was statistically significant in ex-vivo extracorporeal thrombosis experiment of mongrel dog. The thickness of neointima (Tao: 100 ± 20 μm; Tep: 500 ± 150 μm, p < 0.01) and the area ratio of intimal response at 4 weeks (ARao: 0.62 ± 0.22; ARep: 1.15 ± 0.42, p < 0.001) on the implanted iliac stents of New Zealand rabbit could be a function of the oxide properties. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006

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