Heterogeneous surface properties on wallstents

Abstract

Wallstent has been successfully used to open up clogged peripheral arteries. Co-Cr alloy is the preferred metal for the construction of wallstent. Unfortunately, major complications such as in-stent intimal hyperplasia,stent obstruction, and stent stricture are often reported, and these complications could be related to the metallic properties of the wallstent. In this study, the electrochemical properties of Co-Cr wires from wallstent were investigated using cyclic polarization, open-circuit potential, potentiostatic condition, and electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray mapping were also employed to investigate the surface morphology and elemental distribution after electrochemical measurement. Results of this study showed the heterogeneous electrochemical properties of Co-Cr alloy wires that could result in severe galvanic corrosion of wallstent after implantation. Severe corrosion process could cause fracture of wallstent, resulting in localized inflammation, allergy, and thicker neointima.

Electrochemical characterization of vascular bare-metal stents. A novel approach modifying the mini-cell system

“…The OCPs retrieved from FeCrNi using serum were within the same range compared to steel wires using Ringer's solution [40]. Potentials previously reported from CoCr wires were different from our results [23], which was likely due to a differing alloy composition.…”

“…Furthermore, the aim was to investigate stents in a final deployed form and finished condition as all steps in manufacturing potentially influence corrosion properties [22]. Additionally, multi-focal and spotty examination was intended to enable the detection of inhomogeneities as they have been described to enhance corrosion [23]. Hereupon, immersion testing appears to be inadequate.…”

Sensing Localized Surface Corrosion Damage of CoCrMo Alloys and Modular Tapers of Total Hip Retrievals Using Nearfield Electrochemical Impedance Spectroscopy

“…Our data agrees with previous studies on the heterogeneities that exist on metallic biomaterial surfaces. For example, CoCr wallstent wires have reported nonuniform electrochemical properties, such as interfacial resistance and capacitance, 37 where significant changes in impedance values were associated with premature fracture of the wallstent. Indira and Nishimura 38 similarly observed an impedance drop over scratched Cr−steel surfaces compared to the unabraded areas, with increasing chromium content resulting in higher impedance values and increased corrosion resistance in oxidized scratched locations.…”