Coronary stenting: From optical coherence tomography to fluid dynamic simulations

The presence of stents within coronary arteries alters the hemodynamic condition. Computational fluid dynamics (CFD) simulations offer the possibility to study local hemodynamics of a stented artery to identify the stimuli of instent restenosis, i.e. the local reduction of lumen size after stent deployment. The results of CFD simulations are more accurate when the analyses are performed with a model reproducing real in vivo conditions. For this purpose, optical coherence tomography (OCT) is a promising tool to reconstruct 3D geometries of stented coronary arteries, due to its higher resolution compared to the other imaging techniques. In the present work a reconstruction method of stented coronary bifurcation geometrical models starting from OCT images was developed. An OCT exam performed in a stented coronary bifurcation silicone sample was considered. The vessel and the stent were reconstructed separately, and then they were merged together. Vessel reconstruction was performed with a semi-automatic process: the main branch was reconstructed by fitting the lumen boundary with ellipses and subsequently by creating a mesh of the vessel; the side branch was created like an ideal cylinder. Stent struts were identified with an automatic algorithm; then, the stent was reconstructed in a manual way. After the creation of the 3D geometry of the bifurcation, a transient fluid dynamic simulation was carried out. CFD results showed that the highest risk of restenosis is located in the region near the bifurcation.