The Research Of Hemodynamics Of Pre-and Post-endovascular Repair On Stanford B Aortic Dissection

Objective:To establish the individualized model of pre- and post-endovascular repair on Stanford B aortic dissection based on Computational Fluid Dynamics technique. The models are researched by the Finite Element Analysis. The hemodynamic parameters are obtained to investigate the how hemodynamic of pre endovascular repair and post endovascular repair on Stanford B aortic dissection.Methods:(1)3 cases were selected,2 cases were chronic aortic dissection(1 case with only one lesion, the other one with two or more lesion) and 1 case was acute aortic dissection. The original DICOM format image data of pre- and post-endo vascular repair, which was 1 week after the operation, from patients with Stanford B aortic dissection were imported to the Software Mimics. Then the 3D object was constructed by the software.(2) The models are surface meshed and body meshed by the CFD Software. Then establish the finite element models.(3) Compute the hemodynamic parameters of finite element models with the FLUENT software and collect the related data.(4) Import the data into the Ansys Software to post-processing. Then analysis the hemodynamic parameters of pre- and post-endovascular repair on Stanford B aortic dissection in every position at different time points.Results:(1)The individualized model of pre- and post-endovascular repair on Stanford B aortic dissection were constructed successfully based on Computational Fluid Dynamics technique. The detailed aortic dissection hemodynamic parameters were obtained. Then display the streamline, velocity field, pressure and wall shear intuitively of internal aorta. (2)In chronic aortic dissection case, there are low velocity field, much eddy current and higher pressure in the false lumen, and wall shear depends on the entrance direction false lumen. In acute aortic dissection case, there are higher pressure and more unstable flow in the true lumen.(3)There is higher pressure, lower wall shear and more stable flow in post-endovascular repaired chronic aortic dissection case, but there are still unstable flow and large changed wall and pressure in false lumen, meanwhile, the residual false lumen could develop to the distal aorta. In post-endovascular repaired acute aortic dissection case, from the descending aorta pressure began to decrease, and there are higher wall shear and more unstable flow in the residual false lumen.Conclusions:(1)The methods to construct 3D model are quick and accurate.(2)In chronic aortic dissection case, there is still unstable flow at residual lesion after endovascular repair. In acute aortic dissection case, the hemodynamic parameters are unstable after endovascular repair.(3)In this research, the effect of endovascular repair is good in chronic aortic dissection case, but not very good in acute aortic dissection case. If the effect of endovascular repair were summarized systematically, more cases are needed.(4)The changes of the hemodynamic factors are related to the atherosclerosis and the thrombosis. The changes of the hemodynamic factors in the short term could lead to injury and rupture of aortic wall, which is closely related to the further development of residual lesion.(5)The occurrence and development of aortic dissection is related to the hemodynamic factors.