Abstract: Evaluating The Effects of the Anastomotic Angle and Compliance Mismatch on the Hemodynamics of an End-to-Side Graft

Peripheral vascular disease is an adverse condition which creates a need for interventions such as stents, angioplasty, and bypass grafts. For the indication of peripheral vascular disease, small diameter (<4mm) peripheral vascular grafts are widely used in clinical practice. A key factor of bypass graft failure, particularly in synthetic vascular grafts, is the development of intimal hyperplasia, or an accumulation of smooth muscle cells in the vascular tunica intima often in response to injury of a blood vessel. Although there is existing research on the development of intimal hyperplasia for end-to-end grafts using an ex vivo organ culture model, end-to-side grafts are the most common type of vascular grafts to fail (Post et al., 2019). Therefore, pathological hemodynamics that result in end-to-side graft failure can be examined by using computational models to simulate fluid-solid interactions between the host artery and the graft at the anastomosis. In previous studies, irregularities in hemodynamic conditions such as high or low wall shear stress gradients and oscillations have demonstrated a correlation to intimal hyperplasia (Ojha, 1994). Vascular grafts can experience abnormal wall shear stress gradients and oscillations at different angles of connection or if a compliance mismatch between the graft and the artery exists. Furthermore, there is a need to understand the pathological characteristics of small diameter vascular grafts that lead to failure while accounting for experimental cost by developing simulations that can be used to reduce the need for in vivo/ex vivo experiments. In our study, we designed a numerical simulation that tested the effect of the angle of the anastomosis and will further test the effect of graft compliance on the occurrence and severity of pathological hemodynamics, which are known to contribute to the progression of intimal hyperplasia.