Stent strut configurations for patent ductus arteriosus morphologies using computational fluid dynamics analysis

Abstract

The stent implantation in patent ductus arteriosus (PDA) is an alternative palliative treatment of neonates with cyanotic congenital heart disease. However, complications such as in-stent restenosis after stent implantation have been reported by medical practitioners. Researchers identified that the stent strut configurations and the ductal morphology contributed to the problem. Thus, this study focused on improving and developing customized stent strut configurations for PDA stenting applications in different PDA morphologies. Computational fluid dynamics (CFD) analysis was used to analyse the stent performance due to hemodynamic characteristics in PDA. Experimental validation via particle image velocimetry (PIV) analysis was also performed by comparing the velocity profile with the computational analysis. Current commercial stents used in PDA stenting were compared to determine the stent strut configurations with minimal risk of in-stent restenosis formations. Hemodynamic performance parameters in reducing the risk of in-stent restenosis formation such as wall shear stress, wall shear stress gradient, oscillatory shear index, and relative residence time were analysed and compared. All the commercial stents were later scored and ranked based on each hemodynamic performance. Based on the results obtained from the commercial stent hemodynamic performance analysis, parametric stent strut configurations were developed. Two design parameters were considered, which were stent thickness and strut width. The parametric stent strut configurations were analysed using the same hemodynamic performance parameters. The parametric stents were compared with the selected commercial stents with good hemodynamic performance and later selected for structural analysis. Finally, structural analysis via fluid-structure interaction (FSI) modelling was performed to predict parametric stent strut failure due to hemodynamic forces based on the maximum displacement and von Mises stress. Results indicated that a good hemodynamic performance in reducing the risk of in-stent restenosis in commercial stents Type 3, Type 4, Type 5, and Type 6 with more minor strut connectors. Using the results obtained, parametric stent strut configuration was designed and evaluated. Stent with 0.1 mm thickness such as Type A, Type D, and Type G exhibited better hemodynamic performance in reducing the risk of restenosis formation compared to thicker stent strut. In addition, these stents were predicted to being able to withstand the hemodynamic forces from structural failure. Finally, the proposed parametric stents can reduce the risk of the formation of in-stent restenosis by approximately 20% compared to commercial stents with good structural strength to withstand the forces due to blood flow through various PDA morphologies.