Hemodynamic Principles of Endografts

Endovascular aneurysm repair (EVAR) is considered the treatment of choice for abdominal aortic aneurysms (AAA). Despite improvements in techniques and continuous developments in the utilized endografts, EVAR continues to be amenable to early and late complications, like migration and loss of central sealing, stenosis, and thrombosis of the iliac limbs, leading to considerable rates of reinterventions. Modern research provides useful and irreplaceable tools to study and compare the hemodynamic characteristics of endografts, predict their clinical performance, and help to avoid adverse effects. Computational studies focus on hemodynamic indices such as relative residence time (RRT), oscillatory shear index (OSI), or time-averaged wall shear stress (TAWSS), the magnitude and distribution of which are related to thrombosis induction apart from the displacement forces (DF) that act on different segments of the endografts and predispose to migration or dislodgment of their modular segments. Certain geometrical factors, such as neck angulation, iliac bifurcation, endograft curvature, neck-to-iliac diameter and length ratios, structural characteristics of the mainbody, and the iliac limbs can affect or dictate the hemodynamic behavior of endografts postinterventionally. The unique anatomy of a certain aneurysm defines a hemodynamic environment where the implantation of endografts of different geometric characteristics evokes different hemodynamic and clinical performance. There is no ideal endograft design; rather, every AAA has a unique anatomy served better by some designs than others and vice versa. The information provided could help both clinicians and manufacturers toward better operational planning and further development of endograft designs especially in the current era of innovative custom-made patterns. It is crucial to underline the collaboration of clinicians and technicians to interpret the findings of the relevant studies.