Computational hemodynamic analysis of idealized coronary arteries with cylindrical and conical stents

In Brazil, coronary angioplasty with stent implantation is a primary intervention for cardiovascular diseases, yet in-stent restenosis remains a significant complication. Recent proposals suggest transitioning from traditional cylindrical stents to conical geometries to better align with vascular physiology. This study aims to compare the performance of cylindrical and conical stents and investigate the influence of varying strut thicknesses on hemodynamic parameters. The study employed computational modeling using both Fluid-Structure Interaction (FSI) and Computational Fluid Dynamics (CFD) simulations to quantify hemodynamic parameters including Time-Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), and Relative Residence Time (RRT). A total of 12 simulations were performed (6 FSI and 6 CFD) on models of cylindrical and conical arteries with stent strut thicknesses ranging from 0.1 mm to 0.3 mm. The finite volume method was used for the fluid domain, while the finite element method was applied to the solid domain (arterial wall and stent). Blood was modeled as a non-Newtonian fluid using the Carreau model, with Reynolds numbers from 251 to 381 and Womersley numbers from 2.23 to 3.78. Quantitative analysis revealed that rigid-wall CFD consistently underestimates the risk of restenosis compared to FSI. Specifically, FSI predicted areas of critical Time-Averaged Wall Shear Stress (TAWSS ≤ 1 Pa) that were 12% to 46% larger than those predicted by CFD. Strut thickness emerged as a dominant factor; increasing thickness to 0.3 mm resulted in WSS values approximately three times lower than the 0.1 mm models, significantly expanding recirculation zones. Regarding geometry, while cylindrical stents exhibited concentrated high Oscillatory Shear Index (OSI) at the distal edge, conical stents demonstrated a more distributed OSI pattern and a markedly improved Relative Residence Time profile, reducing peak RRT at the distal edge by approximately 60% compared to cylindrical models ( 12 . 25 P a − 1 vs. 29 . 94 P a − 1 ), thereby mitigating stagnation and potential edge restenosis. The findings confirm that neglecting arterial compliance (CFD only) leads to a substantial underestimation of hemodynamic risk. Both stent geometry and strut thickness are critical; while conical stents offer better risk distribution, thicker struts can negate these benefits. Optimizing these parameters is essential for next-generation stent designs. • FSI simulations predict critical risk areas up to 45% larger than rigid-wall CFD, proving compliance is essential. • Conical stents exhibit distributed oscillatory shear patterns, mitigating the concentrated edge-restenosis risk of cylindrical models. • While beneficial for OSI distribution, the stent-aligned conical geometry induces inlet flow deceleration and lower TAWSS. • Strut thickness is a dominant factor; increasing thickness to 0.3 mm significantly expands wake regions in both geometries. • Optimal stent selection requires balancing TAWSS maximization (cylindrical) with OSI distribution (conical).