| In cardiovascular and cerebrovascular diseases,human health is threatened by intracranial aneurysms due to its high morbidity and mortality.Hemodynamics plays an important role in the growth,development and rupture of intracranial aneurysms.Considered the actual elasticity factor of the aneurysm,the influences of different wall compliance,flow conditions and stent shape on the hemodynamics of the aneurysm are studied by numerical simulation method.And the flow behavior changes and flow characteristics within the aneurysm are investigated experimentally.A lattice Boltzmann model of rigid-walled intracranial aneurysm is established,and the blood flow characteristics in the aneurysm under different blood flow conditions and stent morphologies are analyzed based on the mesoscopic scale.The results show that the blood flow in the aneurysm is a vortex motion,and the risk of rupture is mainly concentrated in the corner of the aneurysm facing the inflow of blood.When the human body is in a state of high blood flow,the distribution of the flow field in the aneurysm is more complex.The flow velocity and wall shear stress in the aneurysm are higher than those in the normal state,and the rupture of the aneurysm is more likely to occur.Interventional stenting of aneurysms can effectively reduce the velocity at the neck of the aneurysm and the wall shear stress within the aneurysm,thereby reducing the risk of aneurysm rupture.The feasibility of the application of double stents and variable-spacing stents is explored.The results show that the intervention of double stents and anterior densified stents in the aneurysm has certain advantages in the prevention of aneurysm rupture.The intra-aneurysm velocity reduction after double-stent insertion can reach90.39%,and the velocity reduction after insertion of anterior densified stents can reach 80.29%.The elastic wall simulation is realized by coupling the lattice Boltzmann model and the lattice spring model,so as to study the effect of wall elasticity on the blood flow phenomenon in the aneurysm.The results show that the elastic wall aneurysm is deformed by the fluidstructure coupling effect with the change of the flow in the aneurysm,and the shape of the wall surface at the two aneurysm corners of the aneurysm is changed significantly.Compared with rigid-walled aneurysms,the blood flow velocity at the corner of the elastic-walled aneurysm slows down,and the wall shear stress decreases,that is,the elastic wall can play a certain buffering role and reduce the risk of aneurysm rupture.Conversely,hardening of the blood vessel wall makes the aneurysm more prone to rupture.The deformation of the elastic aneurysm becomes smaller after the stent is inserted,and the stent acts as a diversion in the blood vessel.At the same time,interventional stents attenuate the effect of wall compliance on hemodynamics within the aneurysm.An in vitro model experiment platform of elastic wall aneurysm interventional stent is set up,and flow experiments are carried out on different aneurysm models under different flow conditions.The results show that the blood flow properties within the aneurysm vary with the pulsatile cycle.The elastic effect of the wall makes the pressure change in the tube get feedback regulation,relieving the pulsating impact of blood flow on the tube wall.And wall compliance causes the aneurysm to retain part of the blood flow during the pulsatile cycle.Compared with low flow conditions,the changes of flow parameters in the aneurysm are larger and the blood flow retained in the elastic aneurysm increases under high pulsatile flow conditions,resulting in poor stability of the aneurysm.When the pulsatile flow in the tube is too large and exceeds the range that can be adjusted by the elasticity of the blood vessel wall,the influence of the elastic effect will be weakened.The interventional stent reduces the impact of flow changes in the aneurysm under pulsatile flow conditions,and reduces the blood flow retained in the elastic aneurysm cavity. |
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