In Vitro Hemodynamics Experimental Study On Coronary Artery Stent Couple System

With the improvement of the quality of people's life,cardiovascular disease has become one of the major killers of human health.One of the major treatments of coronary disease currently is stent implantation with the main defect of restenosis.It is essential to study the intravascular hemodynamics after stent implantation to prevent the occurrence of the in-stent restenosis.In order to explore the relationship between restenosis and wall shear stress in pulsatile flow,this paper focuses on the blood vessel coupling system and studyes hemodynamics in vitro.Specially,innovative research findings are elucidated as follows:(1)A method of in vitro test of hemodynamics of vascular stent coupling system is proposed.The pulsating flow generated by the peristaltic pump and pressurizing equipment is used to simulate the blood flow in coronary.The technology of high velocity CCD and particle image velocity measurement is used to measure the hemodynamics within the simulated vessels.(2)A test equipment for hemodynamic performance of vascular stent is established.The test equipment is composed of pressure transmitter,flow sensor,signal transmitter,data acquisition card,high velocity CCD,and simulated blood vessel as well as other hardwares.Based on LabVIEW software development platform,a data acquisition card is used to complete the signal acquisition,analysis and report generation.(3)Hemodynamic performance of the stenosis vessels,vascular stent coupling system and normal blood vessels are respectively tested and analyzed based on this self-designed equipment.And the findings are as follows:The bulge of vascular wall affects the blood stream distribution obviousliy.The stagnant region is formed adjoining the bulge.Vortex is prone to appear in this region and it continues to affect the flow of blood.The high change of velocity aggravates the internal friction of blood microelement,and causes fluid mass in the blood.The change of WSS is large,which can increase the shear effect on endothelial cells,increase the inflammatory reaction induced by inflammatory factors,and promote the process of atherosclerosis.After stent implantation,the velocity in the coupling system is significantly lower than that of the stenosis vessel,and no obvious vortex area is found.This proves that the stent depresses the high velocity and high shear state of the stenosis vessels.However,the implantation of stent still partially impedes the blood movement nearby the wall,which caused the wall surface to be in a low wall shear stress state for a long period of time with high risk of restenosis.The blood velocity in normal coronary artery is much smaller than that of narrowed vessels,indicating that the impact of velocity variation is more serious in deseased vessel.The change of the shear stress of vascular wall is small,which shows that the intima of the vessel is subjected to a slight pulsation and has good hemodynamic performance.The above experiments not only verify the feasibility and reliability of the hemodynamics test equipment,but also provide suggestions for the stent optimization.