Hemodynamic evaluation of different stent graft schemes in aortic arch covered stent implantation

Implantation of the left subclavian artery (LSA) stent graft used in fenestration technique of the thoracic endovascular aortic repair (TEVAR) may interfere with the aortic helical blood flow that is believed to have important protective functions against atherogenesis. The present study investigated four different LSA stent graft implantation schemes for their resulted blood flow patterns in the thoracic aortic with hemodynamic computational simulation methods: the flush branch (FB), the protruding branch (PB), the straight cuff branch (SCB) and the cured cuff branch (CCB). The results showed that the PB scheme could slightly enhance helicity of the swirling flow in the aorta, but the other three schemes had less effect on blood flow helicity. The PB scheme produced low-TAWSS, high-OSI and high-RRT around the LSA root, and the FB scheme had similar TAWSS, OSI and RRT in both value and distribution to those in the aorta without LSA stent graft implantation. The SCB and CCB schemes led to less area of high-OSI and high-RRT values along the walls of the LSA branch arteries. The results also showed that the PB scheme would significantly reduce blood supply to the LSA, on the contrary, the CCB scheme enhanced LSA blood supply and less effect on the total blood supply to the three branches of the thoracic aorta. In summary, all of the four schemes have no significant effect on the aortic swirling flow, however, in the terms of TAWSS, OSI, RRT and blood supply to the LSA, the CCB model might be the best option with less area of low-WSS, high-OSI, high-RRT and well blood supply in the LSA.