Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

• Published in: Acta mechanica Sinica 2021-02, Vol.37 (2), p.279-291
• Main Authors: Ferrarini, A., Finotello, A., Salsano, G., Auricchio, F., Palombo, D., Spinella, G., Pane, B., Conti, M.
• Format: Article
• Language: English
• Subjects: Aneurysms; Bending; Blood vessels; Boundary conditions; Classical and Continuum Physics; Computational fluid dynamics; Computational Intelligence; Configurations; Discontinuity; Engineering; Engineering Fluid Dynamics; Fluid dynamics; Grafting; Helicity; Hemodynamics; Occlusion; Patients; Research Paper; Rheological properties; Rheology; Shear stress; Stents; Theoretical and Applied Mechanics; Thrombosis; Tortuosity; Velocity; Velocity distribution; Wall shear stresses; Waveforms
• ISSN: 0567-7718; 1614-3116
• DOI: 10.1007/s10409-021-01066-2

Endovascular treatment of the femoro-popliteal artery has recently become a valuable therapeutic option for popliteal arterial aneurysms. However, its efficacy remains controversial due to the relatively high rate of complications, such as stent occlusion as result of intra-stent thrombosis. The elucidation of the interplay among vessel geometrical features, local hemodynamics, and leg bending seems crucial to understand onset and progression of popliteal intra-stent thrombosis. To this aim, patient-specific computational fluid dynamic simulations were performed in order to assess the intra-stent hemodynamics of two patients endovascularly treated for popliteal arterial aneurysm by stent-grafts and experiencing intra-stent thrombosis. Both Newtonian and non-Newtonian blood rheological models were considered. Results were presented in terms of tortuosity, luminal area exposed to low (< 0.4 Pa) and high (> 1.5 Pa) time-averaged wall shear stress (TAWSS), area exposed to high (> 0.3) oscillatory shear index (OSI), and flow helicity. Study outcomes demonstrated that leg bending induced significant hemodynamic differences (> 50% increase) in both patients for all the considered variables, except for OSI in one of the two considered patients. In both leg configurations, stent-graft overlapping induced a severe discontinuity of the lumen diameter where the proximal stented zone is characterized by low tortuosity, low velocity, low helicity, low TAWSS, and high OSI; while the distal part has higher tortuosity, velocity, helicity, TAWSS, and lower OSI. Sensitivity study on applied boundary conditions showed that the different inlet velocity profiles for a given inlet waveform affect slightly the numerical solution; conversely, the shape and magnitude of the prescribed inlet waveform is determinant. Focusing on the comparison between the Newtonian and non-Newtonian blood models, the area with low TAWSS is greater in the Newtonian model for both patients, while no significant difference occurs between the surfaces with high TAWSS. GraphicAbstract Patient-specific computational fluid dynamic simulations were performed in order to assess the intra-stent hemodynamics of two patients endovascularly treated for popliteal arterial aneurysm and experiencing intra-stent thrombosis. Both Newtonian and non-Newtonian blood rheological models were considered. In both straight and bent leg configurations, stent-graft overlapping induced a severe discontinuity of the lumen diamete