Flow Characteristics Near to Stent Strut Configurations on Femoropopliteal Artery

Abstract

Abstract. Femoropopiteal artery stenting is a common procedure suggested by medical expert especially for patient who is diagnosed with severe stenosis. Many researchers reported that the growth of stenosis is significantly related to the geometry of stent strut configuration. The different shapes of stent geometry are presenting the different flow pattern and re-circulation in stented femoropopliteal artery. The blood flow characteristics near to the stent geometry are predicted for the possibility of thrombosis and atherosclerosis to be formed as well as increase the growth of stenosis. Thus, this study aims to determine the flow characteristic near to stent strut configuration based on different hemodynamic parameters. Three dimensional models of stent and simplified femoropopliteal artery are modelled using computer aided design (CAD) software. Three different models of stent shapes; hexagon, circle and rectangle are simulated using computational fluid dynamic (CFD) method. Then, parametric study is implemented to predict the performance of stent due to hemodynamic differences. The hemodynamic parameters considered are pressure, velocity, low wall shear stress (WSSlow) and wall shear stress (WSS). From the observation, flow re-circulation has been formed for all simulated stent models which the proximal region shown the severe vortices. However, rectangular shape of stent strut (Type P3) shows the lowest WSSlow and the highest WSS between the range of 4 dyne/cm 2 and 70 dyne/cm 2 . Stent Type P3 also shows the best hemodynamic stent performance as compare to others. In conclusion, Type P3 has a favourable result in hemodynamic stent performance that predicted less probability of thrombosis and atherosclerosis to be formed as well as reduces the growth of restenosis.

Comparison of Hemodynamic Performances Between Commercial Available Stents Design on Stenosed Femoropopliteal Artery

“…Moreover, there is also regions where higher pressure is produced on several stents configuration such as Life stent, Smart Flex stent, Tigris stent, Misago stent and Smart Control stent where red spots appear in Figure 7. This is possibly due to the effect of different strut configuration of the stents where irregular shape traps more pressure, thus increase resistance of the stents towards the blood flow and pressure distribution [7]. As expected, the highest pressure drops goes to the same stent which shows the maximum average of pressure as mentioned above.…”

“…Later, the model is stented with the length of 30 mm. The stent is placed at 40 mm from inlet as the stenosis frequently identified there by Paisal et al, [7]. Simplified model is stimulated to study hemodynamic performance via different implantation of commercial available stents.…”

“…The blood flow of femoropopliteal artery with stenting is assumed as incompressible and Newtonian fluid as the femoropopliteal artery is claimed to be one of the large artery [7]. As cited in numerous studies, Newtonian blood model is a suitable approximation blood model that can be used for numerical simulation pertinent blood flow in the artery.…”

“…Steady flow is assumed in the analysis of hemodynamic effect on all models of stent designs. The mean inlet velocity and outlet pressure placed as shown in Figure 4 are taken with the value of 0.10 m/s and 14590 Pa respectively [7]. (1)…”

“…As a result, chances for the formation of atherosclerosis to happen in this condition is high. Therefore, blood flow should not be stagnant in the artery [7].…”