Electrochemical Study For The Evaluation Of Corrosion Of A New Ceramic Stent

LUCILA NAVARRO; JULIO LUNA; DAVID VETCHER; VÍCTOR P. MOLES

TROPICAL JOURNAL OF PHARMACEUTICAL RESEARCH

PHARMACOTHERAPY GROUP

Año: 2014

1596-5996

Background: Metallic coronary stents are placed in a high chloride environment that plays an important role on the corrosion behavior of the implant. Corrosion of stents presents two main risks: release of metallic ions into the tissue and deterioration of the mechanical properties of stents. Release of heavy metal ions could lead to inflammatory mediators and promote in-stent restenosis. Methods: We evaluated the corrosion resistance of a ceramic stent (CST) developed with an innovative surface treatment that involves a multistage immersion in different solutions performed at INTEC-Universidad Nacional del Litoral and compared it with a plain stainless steel stent (SST), and a chromiumcobalt stent (Cr-Co). The stents were evaluated with potentiodynamic polarization studies, unexpanded and after balloon expansion at 12 bars. Ten stents were studied in each group. The corrosion potential (Ecorr) was measured under a virtual open circuit condition, with respect to a reference electrode; and the corrosion current (Icorr) by a potentiodynamic polarization curve measurement, that involved scanning the potential (mV) at a rate of 0.5 mV/s to a final potential of 1.4 V. Micrographic pictures were taken before and after the electrochemical analysis to evaluate the type of corrosion. Statistical analysis: assays were done in duplicate; ANOVA and a multiple range test by Duncan?s variation were performed. Results: The potentiodynamic curves of CST stents exhibited an anodic current density significantly lower than SST and Cr-Co stents: The Ecorr was -0.39 volts (V) for SST stents, -0.617 V for Cr-Co stents and -0.523 V for CST stents (p< 0.05). The Icorr was of 9.8 E-7 Ampere/cm2 (A/cm2) for the SST stents, 1.4 E-9 A/cm2 for Cr-Co stents and 3.6 E-10 A/cm2 for CST stents (p< 0.05). Micrographic pictures showed only light signs of corrosion on the CST, viewed as a changed on the surface color due to oxide deposition. Cr-co micrographic study exhibited a clear intergranular corrosion and SST stents showed a high tendency for pitting corrosion with loss of portions of stent struts. Conclusions: Surface modified ceramic stents showed a better corrosion behavior when compared with stainless steel stents and Cr-Co stents.