关键词: 腹主动脉瘤, 主动脉血管异常形变, 血流动力学, 预防

Abstract: Background　The clinical data shows that the incidence of abdominal aortic aneurysm（AAA） is rising.A large number of studies have found that the cause of AAA is not only the internal cause of blood vessel biochemical properties，but also the external cause of blood hemodynamics.From the point of view of "stress-growth theory" of biomechanics，the abnormal hemodynamic environment will lead to the remodeling of pulmonary vascular structure，causing vascular diseases.Objective　To investigate the effect of internal hemodynamics on the generation and development of AAA in the case of abnormal deformation of the aortic blood vessels.Methods　The clinical CT image data of one case with healthy aortic vessel and two cases with typical AAA aortic vessel lesions in the Department of Neurology，Affiliated Hospital of Inner Mongolia University for Nationalities were collected in this article from 15 June 2016 to 31 July 2017.Three cases of CT data were reconstructed into a three-dimensional vascular structure model consistent with the real blood vessel using medical image three-dimensional reconstruction technology，and the numerical simulation was carried out using computational fluid dynamics software FLUENT 14.5.Based on the calculation results of hemodynamic characteristics in different vascular structure models with the same blood flow entrance velocity，the distribution of different blood wall shear stress，the distribution of blood flow after AAA in vascular and the secondary flow were compared，to explore the changes of hemodynamic characteristics in blood vessels after abnormal bending and distortion，and analyze the reason of hemodynamics caused by AAA.Results　On the premise of the same inlet velocity，and compared with the blood flow in the aorta of healthy person，the velocity and direction of blood flow decreased in the curved aortic arch of two AAA lesion models，and obvious circulation was found in the medial region of curved aortic arch.By calculating the distribution of secondary blood flow in the cross section of AAA model of arterial structure，it was found that the blood flow at the aortic arch appeared vortex flow，and the blood flow was normal after passing through the aortic arch，and the blood flow velocity was relatively low，the blood flow velocity at the bend of AAA increased locally.Compared with the tangential stress distribution of healthy blood vessel model，except for the large tangential stress at each outlet of blood vesselszthe tangential stress of aortic arch segment of human body was smaller，but the wall tangential stress of healthy blood vessel was slightly larger，and the distribution of tangential stress on the wall of blood vessel was more uniform in healthy human body.Conclusion　Compared with healthy human body，the abnormal bending and distortion of blood vessels of AAA are accompanied by secondary flow，and the phenomenon of secondary flow with high-speed and vortex can cause irreversible impact on the vessel wall，and thus causing the generation of AAA and increasing diameter of AAA gradually.