Effects Of Different Position Of Intravascular Stent Implantation In Stenosed Vessels On In-stent Restenosis

Percutaneous coronary intervention is the most effective way to treat such diseases.After recent years of development,it has been widely used in clinical practice,but advanced in-stent restenosis has not been completely resolved.Studies have shown that changes in the intravascular mechanical environment after stent implantation induce in-stent restenosis.An in-depth understanding of the effects of stent intervention on the microenvironment of vascular mechanics is important for clinically optimizing stent placement and relieving in-stent restenosis.Based on this,this paper uses numerical simulation method to study the stent implantation process and postoperative intravascular hemodynamics,and uses animal models to verify.The main contents and results are as follows:?1?Region in the proximal part of the stent promotes atherosclerotic plaque regeneration:parameterization modeling method was used to construct a stenotic vessel model.The mechanical response of the stenotic vessels during stent implantation and the hemodynamic environment within the vessel after stent implantation were simulated.The simulation results show that the wall stress of the stenotic vessels changes significantly during stent implantation,and the maximum stress appears in the front and rear ends of the stenosis.The hemodynamic characteristics at the proximal part of the stent are obvious,low shear stress,high oscillating shear,and low shear rate,risk of restenosis in the proximal vessel is higher.?2?Based on the numerical simulation of image data,it was confirmed that there were low shear stress and high oscillating shear at the proximal part of the stent segment:15 male New Zealand white rabbit necks were constructed by using balloon intima.The intravascular stents were implanted into different locations of the stenotic vessels.Effects of different positions of the stent on the mechanical environment of the stenotic vessels were analyzed.The simulation results showed that there were low shear stress,high oscillating shear and high relative residual time at the proximal part of the stent segment,and there was a significant correlation between the above three parameters and the stent implantation position(r_TAWSS=-0.718,r_OSI=0.898,r_RRT=0.818,p<0.01),the correlations between hemodynamic parameters of the middle and distal segements and stent position were nonsignificant.?3?Based on animal experiments,the intimal hyperplasia at the entrance of the stent segment was confirmed to be severe,and there was a significant correlation with the stent implantation position:the section of the stent segment was stained,and the results showed the degree of intimal thickening at the proximal part of stent segment deepened with the position of stent,but there was no significant difference between the intimal thickening at the middle and distal segment of stent and the position of stent.In conclusion,the results show that stent implantation can significantly change the mechanical environment of the blood vessel,and form atherosclerotic plaque area near proximal part of stent segment.As the position of stent continues to lag behind,the impact of this area on new plaque and in-stent restenosis is more obvious.Therefore,stent placement should be further optimized during clinical stent intervention.