Near-wall hemodynamic changes in subclavian artery perfusion induced by retrograde inner branched thoracic endograft implantation

Left subclavian artery (LSA)-branched endografts with retrograde inner branch configuration (thoracic branch endoprosthesis, TBE) offer a complete endovascular solution when LSA preservation is required during zone 2 thoracic endovascular aortic repair (TEVAR). However, the hemodynamic consequences of the TBE have not been well-investigated. We compared near-wall hemodynamic parameters before and after the TBE implantation using computational fluid dynamic (CFD) simulations. Eleven patients who had undergone TBE implantation were included. Three-dimensional (3D) aortic arch geometries were constructed from the pre- and post-TBE implantation computed tomography images. The resulting twenty-two 3D aortic arch geometries were then discretized into finite element meshes for CFD simulations. Inflow boundary conditions were prescribed using normal physiologic pulsatile circulation. Outlet boundary conditions consisted of Windkessel models with previously published values. Blood flow, modeled as Newtonian fluid, simulations were performed with rigid wall assumptions utilizing SimVascular’s incompressible Navier-Stokes solver. We compared well-established hemodynamic descriptors: pressure, flow rate, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and percent area with OSI >0.2 (%A OSI>0.2). Data were presented on the stented portion of the LSA. TBE implantation was associated with a small decrease in peak LSA pressure (153 [IQR = 151 – 154] mmHg vs 159 [IQR = 158 – 160] mmHg, p = 0.005). No difference was observed in peak LSA flow rates between pre- and post-implantation: 40.4 [IQR = 39.5 – 41.6] cm3/sec vs 41.3 [IQR = 37.2 – 44.8] cm3/sec, p = 0.59. There was a significant post-implantation increase in TAWSS (15.2 [IQR = 12.2 - 17.7] dynes/cm2 vs 6.2 [IQR = 5.7 - 10.3] dynes/cm2, p = 0.003), leading to decreases in both OSI (0.088 [IQR = 0.063 -0.099] vs 0.1 [IQR = 0.096 - 0.16]; p = 0.03) and percentage of area (%A) with OSI >0.2 (10.4 [IQR = 5.8 - 15.8] vs 15.7 [IQR = 10.7 - 31.9], p = 0.13). Neither LSA side branch angulation (median, 81°, IQR = 77° - 109°) nor moderate compression (16% - 58%) appeared to have an impact on the pressure, flow rate, TAWSS, or %A with OSI >0.2 in the stented LSA. The implantation of TBE produces modest hemodynamic disturbances which are unlikely to result in clinically relevant changes.