Contribution of Mechanical and Fluid Stresses to the Magnitude of In-stent Restenosis at the Level of Individual Stent Struts

Structural and fluid stresses acting on the artery wall are proposed as mechanical mediators of in-stent restenosis (ISR). This study reports an investigation of the correlation between stresses obtained from computational simulations with the magnitude of ISR at the level of individual stent struts observed in an in vivo model of restenosis. Structural and fluid dynamic analyses were undertaken in a model based on volumetric micro-CT data from an in vivo stent deployment in a porcine right coronary artery. Structural and fluid mechanics were compared with histological data from the same stented vessel sample. Interpretation of the combined data at the level of individual stent struts was possible by identifying the location of each 2-D histological section within the 3-D micro-CT volume. Linear correlation between structural and fluid stimuli and neointimal thickness at the level of individual struts is less clear when individual stimuli are considered [compressive force (CF), R 2 = 0.19, wall shear stress (WSS), R 2 = 0.25, oscillatory shear index (OSI), R 2 = 0.28]. Closer correlation is observed if combined structural and fluid stimuli are assumed to stimulate ISR (CF/WSS, R 2 = 0.64). The use of micro-CT to characterise stent geometry after deployment enhances the clinical relevance of computational simulations, allowing direct comparison with histology. The results support the combined role of both structural and fluid mechanics to determine the magnitude of ISR at the level of individual struts. This finding is consistent with other studies which consider these stimuli averaged over a transverse section of the vessel.