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

Chun Che Shih, Chun Ming Shih, Kuang Yi Chou, Shing Jong Lin, Yea Yang Su

Research output: Contribution to journalArticle

21 Citations (Scopus)

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 (T ao: 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.

Original languageEnglish
Pages (from-to)861-873
Number of pages13
JournalJournal of Biomedical Materials Research - Part A
Volume80
Issue number4
DOIs
Publication statusPublished - Mar 15 2007

Keywords

  • 316L stainless steel stent
  • Hydrated and hydrolyated oxides
  • Inflammation
  • Neointima
  • Passivated
  • Thrombosis

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials

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