Influence of Left Subclavian Artery Stent Graft Geometry on Blood Hemodynamics in Thoracic Endovascular Aortic Repair

The objective of this research is to analyze the hemodynamic differences in five configurations of left subclavian artery (LSA) stent grafts after LSA endovascular reconstruction in thoracic endovascular aortic repair (TEVAR). For numerical simulation, one three-dimensional thoracic aortic geometry model with an LSA stent graft retrograde curved orientation was reconstructed from post-TEVAR computed tomography angiography (CTA) images, and four potential LSA graft configurations were modified and reconstructed: three straight (0, 2, and 10 mm aortic extension) and one anterograde configuration. The blood perfusion of the LSA, flow field, and hemodynamic wall parameters were analyzed. The vortex evolution process was visualized by the Liutex method which enables accurate extraction of the pure rigid rotational motion of fluid and is highly suitable for identifying the vortex structure of blood flow near the vessel wall. The average flow in the retrograde configuration decreased by 11.2% compared to that in the basic configuration. When the LSA stent graft extends in the aortic lumen, flow separation is observed, and vortex structures begin to form at the proximal inferior arterial geometry and the wall of the extension in late systole. A greater extension length and inflow angle upstream resulted in a greater oscillatory shear index (OSI) and relative residence time (RRT) on the nearby wall of the posterior flow field of the extension. Shorter intra-aortic extension length (<10 mm) and smaller LSA stent graft inflow angle (<120 deg) may be recommended in TEVAR, considering LSA perfusion and minimized flow field disturbance.