The Preliminary Study Of The Effect Of Fluid Shear Stresson The Stents Degradation Rate

With the continuous improvement of people’s living level and the change of diet structure, the cardiovascular disease incidence rate is increasing, cardiovascular stent technology has become the most popular means in the treatment of coronary heart disease. As the harm of permanent stents have been widely recognized, biodegradable stent replace it as the first choice. But the uncontrollable degradation rate of biodegradable stent become the biggest obstacle to its further development. This paper introduced the development course, current situation, and research methods of vascular stent and biodegradable stent at first, and analyse the current shortcomings of biodegradable stent, points out the importance of shear forces on the degradation situation.This paper carry out experiment to study the degradation of the lower bracket convection field, and the finite element simulation, by comparing experimental results with simulation results, get the qualitative effect of shear stress distribution on the scaffold degradation rate analysis.In experiment, we designed the stent degradation system, through the light microscope observation before and after degradation of the morphological changes, and then, we simulated by using numerical method, to analyse the flow field around stent, by comparing the experimental results with simulation, the main conclusion is as follows:1) The degradation of stent in the flow field has inhomogeneity;2) The degradation of stent elbow is not significant, degradation obvious areas are mainly concentrated in the bracket main reinforcement;3) The low shear stress area mainly concentrated in the elbow;4) The angle of flow direction and stent increases will produce more low shear stress area.Finally, we simulated by using numerical method, the distribution of different shear stress generated on the stent implantation after different structure, we get the following conclusions:1) The wall thickness increases will produce more low shear stress area obviously;2) The complexity of stent structure increase will produce(small) more regions of low shear stress, and more ununiformolly shear stress distribution;3) The connection bar increases will increase low shear stress area.