The Study Of The Mechanism Of New Iliac Vein Stent In Stenosis Vessel

Iliac Vein Compression Syndrome(Iliac Vein Compression Syndrome)is a disease in which the left Iliac Vein is stimulated by the posterior lumbosacral vertebra and the anterior right Iliac artery,resulting in chronic injury,adhesion and narrowed luminal space of the left Iliac Vein.The emergence of stent implantation has provided safe and effective treatment for patients,so it has been favored by patients and doctors in clinic.In this paper,aiming at 4 new iliac vein stent,Combined with nonlinear finite element method and computational fluid dynamics,analyses the new iliac vein stent(10mm,12 mm,14mm,16 mm diameter)implanted different stenosis rate(normal,30%,50%,70%)of the iliac vein(diameter of 9mm,10.8mm,12.6mm,14.4 mm)of the mechanical properties and blood flow and using in vitro experiment device,testing outlet average velocity within the blood vessels after their released,verify the correctness of the finite element analysis.(1)After the stent released in the stenosis vessels,the high stress-strain regions were located at the stenosis.With the increase of vascular stenosis rate,the equivalent stress and elastic strain of the stents also tend to increase,but the maximum stress-strain did not exceed the stress-strain limit of Nitinol alloy.After the fatigue cycle load is applied,the alternating strain of the stents did not exceed the fatigue limit value of Nitinol alloy,and the safety factor of the fatigue strength of the support is greater than 1,satisfying the requirement of 10 years of fatigue life.(2)After the stent released in the stenosis vessels,the stress and strain of the left iliac vein was higher than that of the right iliac vein.With the increase of the stenosis rate,the maximum strain and stress of the vessel wall tend to increase.The stress-strain of the stenosis vessels was higher than that of the normal vessels,which was corresponding to the stressstrain of the stents.(3)After the stent released in the stenosis vessels,with the increase of the stenosis rate,the maximum flow velocity and the maximum pressure of the vessel tended to increase.The blood flow velocity increases gradually from the inlet to the outlet,and the blood pressure increases gradually from the outlet to the inlet.The analysis of the proportion distribution of vessels wall shear stress showed that after implantation of the 4 stents,with the increase of stenosis rate,the low wall shear stress less than 0.5Pa decreased,the high wall shear stress greater than 5Pa increased,and the wall shear stress between 0.5Pa and 5Pa tend to decrease.(4)After setting up the experimental device,it was found that after stent implantation,the outlet average velocity increased with the increase of the stenosis rate.The stent is implanted into normal blood vessels,vascular roughness for simulation is lower than the roughness of the blood vessel in vitro experiments,the simulated experimental value is slightly higher than the in vitro experimental value,for 0.038m/s.After the stent is released into vessels with 30% and 70% stenosis rate,besides the influence of vascular roughness,narrow area is slightly bigger than the whole simulation blood vessels in vitro experiment,the in vitro experimental value was slightly higher than the simulated experimental value,for 0.026m/s and 0.098m/s.Using the finite element method and in vitro experimental method,analyses the new iliac vein stent was released into the vessels with different stenosis rates,and reveal the influence of stenosis rate on the mechanical properties and blood flow field,which provided an important reference for the development and clinical treatment of the new stent.