No abstract

Coronary artery disease is responsible for a third of global deaths worldwide. Computational simulations of blood flow can be used to understand the interactions of artery/plaque and blood in coronary artery disease and to better predict the rupture of atherosclerotic plaques. So far, the mechanical properties of animals' coronary artery have been mostly used for hemodynamic simulation of atherosclerotic arteries. The mechanical properties of animals' coronary arteries are often not accurate enough and can be only used for an approximate estimation and comparative assessment of the cognate parameters in human. In this study, a three-dimensional (3D) computational fluid-structure interactions model with three different plaque types is presented to perform a more accurate plaque vulnerability assessment for human atherosclerotic plaques. The coronary arteries of twenty-two male individuals were removed during autopsy and subjected to uniaxial tensile loading. The hyperelastic material coefficients of coronary arteries were calculated and implemented to the computational model. The fully coupled fluid and structure models were solved using the explicit dynamics finite element code LS-DYNA. The normal and shear stresses induced within the plaques were significantly affected by different plaque types. The highest von Mises (153 KPa) and shear (57 KPa) stresses were observed for hypocellular plaques, while the lowest von Mises (70 KPa) and shear (39 KPa) stresses were observed on the stiffer calcified plaques. The results suggest that the risk of plaque rupture due to blood flow is lower for cellular and hypocellular plaques, while higher for calcified plaques with low fracture stresses.

The stresses induced on plaque wall during stent implantation inside a stenotic artery are associated with plaque rupture. The stresses in the plaque-artery-stent structure appear to be distinctly different for different plaque types in terms of both distribution and magnitude. In this study, a nonlinear finite element simulation was executed to analyze the influence of plaque composition (calcified, cellular, and hypocellular) on plaque, artery layers (intima, media, and adventitia), and stent stresses during implantation of a balloon expandable coronary stent into a stenosed artery. The atherosclerotic artery was assumed to consist of a plaque and normal arterial tissues on its outer side. The results revealed a significant influence of plaque types on the maximum stresses induced within plaque wall and artery layers during stenting, but not when calculating maximum stress on stent. The stress on stiffer calcified plaque wall was in the fracture level (2.21 MPa), whereas cellular and hypocellular plaques play a protective role by displaying less stress on their wall. The highest von Mises stresses were observed on less stiff media layer. The findings of this study suggest a lower risk of arterial vascular injury for calcified plaque, while higher risk of plaque ruptures for cellular and hypocellular plaques.

No abstract