Effect of Expansion Pressure on the Drug Eluting Coating and the Corrosion Characteristics of Coronary Stents

Abstract During implantation, stents are delivered in crimped state to the narrowed lesion, where they are expanded to the desired size by the balloon. Due to insufficient size selection or high resistance to plaque, the stent is often widened by the expansion pressure to a level greater than the nominal pressure specified by the manufacturer. Depending on the degree of overpressure, the nominal diameter of the stent may change by several tenths of a millimetre. Numerous studies have dealt with the physiological effects of overexposure and stenogenic stress, but so far no studies have been carried out to investigate the stent coating and corrosion properties of the stent. In our research a widely used drug-eluting, platinum-chromium alloyed steel stent was observed with an inflation pressure of 12 and 18 bar. Scanning electron microscopy revealed lesions of the coating and potentiodynamic tests were performed to determine the corrosion rate.