Modeling Arterial Wall Transport for Drug-Eluting Stents

Drug-eluting stents (DES) are very commonly used for treating coronary atherosclerotic lesions. Despite the broad effectiveness of DES, ∼5% of treated patients experience complications including in-stent restenosis and late-stent thrombosis. The occurrence of these complications depends on various factors including the concentration of the eluted drug in the arterial wall and the rate of arterial re-endothelialization. Drug concentration in the arterial wall needs to be sufficiently high to be efficacious while remaining sufficiently low to avoid compromising wall stability (leading to stent malapposition). Furthermore, because drugs used in DES modulate proliferation rates of not only smooth muscle cells but also endothelial cells, the drug concentration affects re-endothelialization rates. Drug concentration in the arterial wall is determined by the transport and metabolism of the drug and may also be affected by the flow field in the lumen of the stented vessel. In the present study, we develop a computational model of drug transport in the arterial wall. Previous models have typically treated the arterial wall as a homogeneous porous medium [1] and have often ignored drug reaction with cells in the arterial wall [2]. In the present study, we have developed a model that incorporates the multi-layer structure of the arterial wall and have compared its predictions for the distribution of an eluted drug within the arterial wall with those of the single-layer homogeneous wall model.