A Spatiotemporal Analysis of a Fluid Structure Interaction Model of the Left Coronary Artery

Abstract

Coronary artery disease is the second leading cause of death in the United States. Models of coronary arteries have been widely used to understand the hemodynamic drivers of the disease. Fluid-Structure Interaction (FSI) modeling of the coronary arteries provides information on both the forces that are created by the blood and the forces distributed into the artery wall. A better understanding of the artery health and markers of disease progression may be discernable by performing a spatiotemporal analysis of the coronary artery hemodynamics and solid mechanics. The goals of this investigation were: 1) to create a three-dimensional (3D) FSI model of the left anterior descending coronary artery and 2) to evaluate disease progression using multiple mechanical descriptors in both space and time domains using COMSOL Multiphysics. The 3D geometry reconstruction was based on a patient's computer tomography angiography (CTA) data. The fluid domain representing the blood volume and solid domain representing the artery wall were fully coupled. The artery wall was modeled using a 5-parameter hyperelastic Mooney-Rivlin material model. We assessed time averaged wall shear stress, wall shear stress gradient, and oscillatory shear index (OSI) along the fluid-structure interface. Artery wall strain (along the three principal directions) and Von-Mises stress were assessed within regions of the solid (i.e., the vascular wall). A virtual calculation of the Fractional Flow Reserve (vFFR), which is used for clinical diagnosis of cardiac ischemia, was performed. These analyses were collected from three different regions along the artery, proximal to, at, and distal to an area of narrowing in the artery throughout the cardiac cycle. Clear differences were observed between the regions. The distal region to the narrowing had variable OSI and high time averaged wall shear stress, but the lowest average Von-Mises stress. The vFFR was 0.96 which is comparable to the average FFR in the left anterior descending artery. This type of model reconstruction and analysis can be used to evaluate plaque vulnerabilities. It may also have clinical implications when assessing the patient's specific coronary artery mechanical environment that may lead to plaque development and instability.