Fluid Dynamic Analysis On Aortic Dissection Based On Computed Tomography Scan

Aortic dissection, which is also called aortic dissection aneurism, is an acute aortic disease which can bring serious harm to the health of patients. The incident of aortic dissection was found in an increasing trend year by year clinically. If not treated, with the persistent efforts of the pressure in vessel cavity, the extent of the dissection is torn growing, and the vascular wall is becoming thinner. And all of these could eventually lead to rupture of aortic dissection. And the case-fatality rate is as high as 80～90 percent. Methods adopted clinically are conservative treatment and surgical treatment. At present, the pathogenesis of aortic dissection and the aortic dissection rupture location have not been specified clearly, and surgical treatment of aortic dissection is not yet mature. As a result of these reasons, it is meaningful for fluid dynamic analysis on aortic dissection which can provide important guiding significance clinically.Firstly, the current study of more idealized model of aortic aneurysm has been calculated which is used to validate the proficiency and reliability of the numerical method. For the idealized aortic aneurysm, the characteristics of the flow field of the aortic aneurysm and distribution of the shear stress and static pressure of the wall can be gotten by CFD software FLUENT. The interaction between fluid and solid can be calculated by fluid dynamic software ANSYS-CFX. Compared with the normal blood vessels, it is helpful for the clinical treatment of the aortic aneurysm. And the proficiency and the reliability of the numerical method can be validated, which can provide a reliable method for the next calculation of aortic dissection.The major work is based on the 527 slices of aortic dissection obtained by computerized tomography scan. The absolute aortic dissection, true lumen and false lumen can be reconstructed by the medical processing software 3D-DOCTOR and the physical reconstructing software GEOMAGIC. The characteristics of the flow field of the aortic dissection, true lumen and false lumen can be calculated and analyzed by CFD software FLUENT. Thus, distribution of the shear stress and the static pressure of the wall and the initial flap of aortic dissection can be gotten. And the risk position of the wall can also be analyzed, which can provide clinical guidance on the surgical treatment of aortic dissection. In addition, the interaction between the fluid and solid can be gotten by ANSYS-CFX, and the deformation of the true lumen and the false lumen can be analyzed, thus the deformation distribution of the wall can be gotten. The model is real, and the velocity and pressure boundary conditions are obtained by magnetic resonance imaging(MRI). The results show that wall shear stress becomes larger rapidly near the break point. The forward extension of false lumen increases faster than reverse extension. The deformation of the flexible wall is larger than that of the rigid wall, but the shear stress on the flexible wall is much smaller.