Electrochemical Assessment of the Galvanic Corrosion and Metal Ion Release in Overlapping Stent and Vascular Plug Systems

Abstract

Cardiovascular diseases cause the highest global mortality rates and are often treated with surgical interventions such as stent or vascular plug placement. However, in-stent restenosis develops over time depending on the material composition and interactions with body fluids. Current strategies to address restenosis include balloon angioplasty or placing a secondary stent at the same site. A key concern with overlapping stents is the increasing risk of galvanic corrosion, as most cardiovascular stents have metallic composition. This study examines galvanic corrosion rates in different vascular stent and plug combinations using electrochemical corrosion characterization techniques. Three metallic vascular specimens with varying compositions are evaluated. The specimens are immersed in simulated body fluid at 37°C under individual and overlapping conditions. Electrochemical impedance spectroscopy and current density measurements, conducted via potentiostat, provide insights into the corrosion behavior of each specimen configuration. Additionally, inductively coupled plasma mass spectrometry quantifies metal ion release through SBF samples. Results show that combining dissimilar materials in overlapping placements significantly increases galvanic corrosion and metal ion release. The corrosion current density (i_corr) significantly increased from 11.75 μA/cm² in the individual bare-metallic stent to 522.3 μA/cm² in the stent-on-plug configuration. A similar increase was observed in the stent-on-stent configuration, with an i_corr of 132.6 μA/cm². These results corresponded with notable decreases in electrochemical impedance and polarization resistance, measured as low as 0.039 kΩ (Z_T) and 0.057 kΩ cm² (R_P) for the stent-on-plug system. Consequently, the calculated corrosion rate escalated to 2254 μm/year, with a mass loss reaching 42.22 mg/cm²·year. ICP-MS analysis supported these findings, showing the highest levels of metal ion release in the stent-on-plug configuration, with 23.86 ppm of Ni and 0.41 ppm of Cr. These findings highlight the importance of stent-material selection in reducing corrosion-related complications. Implementing material-specific strategies in secondary stent placement can lower the risks of inflammatory host response, stent failure, and their long-term effects.