Numerical study on effects of drug-coating position of drug-eluting stents on drug concentration

As consequences of the implantation of drug-eluting stents (DESs), hemodynamic changes and drug diffusion have significant effects on in-stent restenosis. In particular, the drug-coating position on DESs can affect drug concentration distribution in blood and the vascular wall. Therefore, investigating the effects of the drug-coating position on drug distribution is important for the optimal design of DESs, in terms of both geometry and drug coatings. In this paper, three-dimensional virtual stent models with different drug-coating positions were built to numerically investigate the drug concentration distribution. The results were compared with those from two-dimensional simulation models. It was demonstrated that an increase of the contacting surface increases drug concentration in the vascular wall, and constrains the increase of the low wall shear stress (WSS) region (which normally increases with the height of DESs). The results show that the drug coated on the contacting surface effectively enters the vascular wall without interference from blood flow. Increasing the drug on the contacting surface and decreasing the height of a DES are optimal for reducing the risk of restenosis.