Hemodynamic study of thoracic aortic aneurysm based on computational fluid dynamics technique

Abstract

To establish a patient-specific hemodynamics model of thoracic aortic aneurysm (TAA) based on computational fluid dynamics technique and investigate its role in the study of growth and rupture mechanism of TAA. 3D realistic model of thoracic aortic aneurysm was reconstructed from DICOM format computed tomography angiography (CTA) images of a male patient. The geometry was reconstructed using medical image processing software Mimics. The blood flow in aorta was assumed to be laminar and incompressible and the blood Newtonian fluid. A time-dependent pulsatile boundary condition was deployed at inlet. Unsteady blood flow simulation was performed in real geometry of TAA with a finite volume method (FVM) code FLUENT. The hemodynamic parameters related with the growth and rupture of aneurysm were analyzed. Analysis of the distributions of hemodynamic variables during the cardiac cycle such as wall shear stress, streamlines and velocity profiles in TAA were carried out. The numerical simulation results demonstrated that the blood velocity of proximal neck was considerably faster than that of aneurysm body. The outer wall of proximal aneurysm body was hit by blood jet entering aneurysm. Instant streamlines at peak systole showed that the entering blood stream hit the aneurysm wall and right-hand helical vortex was observed in aneurysm body. The distributions of high wall shear stress were observed in the proximal and distal aneurysm neck and the area where the entering blood stream first hit the wall. Large regions of lower wall shear stress occurred in aneurysm body. The growth and rupture mechanisms of TAA may be analyzed based on a constructed patient-specific model and hemodynamic simulation.