A COMPUTATIONAL STUDY ON STENT GRAFT IMPLANTATION IN DESCENDING AORTA ANEURYSM
Chi Wei Ong, Pei Ho, Hwa Liang Leo
National University of Singapore, Singapore
Thoracic aortic aneurysm (TAA) is one of the serious cardiovascular diseases, which often leads to death if left untreated. Clinical observations showed that growth and progression of an aneurysm are closely linked to the hemodynamics condition of aneurysm sites, such as wall shear stress (WSS) and intravascular pressure. Thoracic stent grafts, commonly known as Thoracic EndoVascular Aortic Repair (TEVAR) can potentially promote recovery of aneurysm by altering the associated blood flow disturbances within the aneurysm besides isolation of aneurysm. However, such data on the hemodynamic impact of a microporous stent-graft on aortic aneurysm are limited. To investigate the hemodynamics changes of microporous stent graft intervention to the TAA, a patient-specific computational fluid dynamic (CFD) studies are performed in a TAA before and after microporous stent graft implantation. The blood was assumed as non-Newtonian fluid. Five cardiac cycles of these pulsatile flow and pressure waveforms were carried out to reduce the unsteady effect of initial cycles. The CFD results were presented and compared in terms of time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residence time (RRT). Reduced TAWSS and OSI were found on the aneurysm wall after the deployment of microporous stent-graft cab that may reduce the chance of artery wall thickening. Elevated RRT on the aneurysms sac showed that red blood cells and platelets tended to stay longer in the aneurysm sac after implantation of the microporous stent graft. Our study showed that microporous stent graft can potentially alter the flow patterns within the aneurysm and leads to a beneficial hemodynamic environment for promoting recovery of aortic aneurysm.