Análise hemodinâmica computacional de artérias coronárias idealizadas com stents cilíndricos e cônicos

Abstract

In Brazil, most hospital admissions for the treatment of cardiovascular diseases involve coronary angioplasty procedures with the use of stents. However, a significant challenge is in-stent restenosis, which involves the accumulation of cells, requiring additional interventions. Despite efforts to improve the geometry and material of stents, a recent approach proposes the transition from cylindrical to conical stent geometry, aiming for better adaptation to the physiology of blood vessels. This study compares cylindrical and conical stents using Fluid-Structure Interaction (FSI) modelling and Computational Fluid Dynamics (CFD). Additionally, it explores the impact of different strut thicknesses (0.1 to 0.3 mm) in 12 simulations, 6 CFD, and 6 FSI, in models of cylindrical and conical arteries. Finite volume and finite element methods were employed to approximate the fluid and solid domains, respectively. Blood was modelled as non-Newtonian fluid using the Carreau model, with Womersley number ranging from 2.23 to 3.78 and Reynolds number from 251 to 381. A different velocity pulse was used for each artery type, with the same flow pulse. The solid domain was represented by the arterial wall and the stent, with their properties obtained through Granta Edupack software. Results highlight the importance of FSI analysis, revealing significant differences compared to CFD in terms of Oscillatory Shear Index (OSI), pressure differences, and Temporal Average Wall Shear Stress (TAWSS), where FSI modelling showed substantial differences over CFD modelling, confirming the significant importance of this analysis method. A greater difference was also achieved between different stent thicknesses, with three times lower stresses for the larger thickness compared to the smaller one. The FSI approach also provided promising results with stresses reaching approximately 25% of the material yield stress of the stent, indicating substantial potential for optimizing coronary stenosis treatment.