Fluid Dynamics Research On 3D Reconstructed Evolution Characteristics Of Aortic Dissection Based On CT-Scan

Type B aortic dissection is a very dangerous vascular disease,with rapid onset,high fatality rate and an increasing incidence with age.Clinically,the pathogenesis of aortic dissection is not completely clear,which brings great difficulties to the prevention and treatment of this disease.However,a lot of studies have shown that the occurrence and development of aortic dissection are closely related to hemodynamic factors.Based on this,in this paper ideal and patient-specific aorta models at different development stages of aortic dissection were constructed respectively,adopt the method of computational fluid dynamics to complete the two-way fluid-structure coupling simulation,obtained the hemodynamic parameters changing with the development of the aortic dissection,at the same time using 3D printing technology and membrane technology to obtain the patient-specific physical aorta models in different development stages of aortic dissection,and an in vitro simulation system was established to conduct the experiment,the computational fluid dynamics and experimental fluid dynamics methods were used to study the variation of hemodynamic parameters at different development stages of aortic dissection,and the pathogenesis and development rules of aortic dissection were discussed in depth,the research results are of great significance for further understanding the generation,development and rupture mechanism of aortic dissection in clinical.The main work is as follows:(1)Based on the aorta size data of normal human body and patients with type B aortic dissection,the three-dimensional modeling software Pro/E was used to construct ideal aorta models at different development stages of aortic dissection.The Workbench platform was used to construct the blood model,generate mesh,set material properties and boundary conditions,etc.Finally,the two-way fluid-structure coupling simulation between blood and blood vessel was completed on the platform.The simulation results show that the high incidence of aortic dissection is related to the complex vortex and high blood velocity.The blood flow condition in the false lumen at different development stages of dissection has significant difference.The maximum Von Mises stress of the blood vessel increases with the development of the aortic dissection,which results in the risk of blood vessel rupture also increases with the development of the dissection.(2)Based on the computed tomography images of a patient with type B dissection,the medical image processing software Mimics,reverse modeling software Geomagic Studio and three-dimensional modeling software UG were used to reconstruct patient-specific aorta models at different development stages of aortic dissection.Also,the Workbench platform was used to the blood model,generate mesh,set material properties and boundary conditions,etc.,and finally,the two-way fluid-structure coupling simulation between blood and blood vessel was completed on the platform.The results showed that the Maximum blood velocity increases with the development of aortic dissection during the accelerated ejection period,at the same time the blood velocity in the aortic arch increased significantly and begin to appear the vortex flow at the late development stage of aortic dissection.The blood flow condition in the false lumen becomes more complicated with the development of the aortic dissection.The Von Mises stress of the blood vessel and the average wall pressure increase with the development of the aortic dissection,which leads to the increased risk of the blood vessel rupture.The average wall shear stress decrease with the development of the aortic dissection,indicating that the risk of re-tearing of the blood vessel decreases with the development of the aortic dissection.In addition,by comparing the Von Mises stress simulation results of patient-specific models and ideal models,it can be seen that:the risk of blood vessel rupture with complex geometry is higher,and we should pay more attention the disease progression of patients with complex geometric shape of aorta in clinical.(3)The design of the simulation of atrial and ventricular organs of 3D model,ABS resin as raw materials by 3D printing made physical model,at the same time with silica gel as the raw materials,combined with 3D printing technology and membrane technology,the high precision,high imitation of natural simulation interlining development in different periods of personalized aortic mock-up.The extracorporeal simulation system was established to study the variation of blood vessel deformation,the mean pressure and flow velocity at the outlet of descending aorta at different development stages of dissection development.The results showed that the compression effect of the false lumen increases with the development of aortic dissection;the max average pressure of the aorta outlet appears at the accelerated ejection period and was decreases with the development of aortic dissection,however the average pressure in the presence of aortic dissection is greater than that without aortic dissection;there is no significant difference in the average velocity of the aorta outlet at different development periods of aortic dissection.