Numerical study on relationship of each index for disturbance to turbulence characteristics in hemodynamics in AVF

Abstract

Vascular access required to perform a dialysis treatment need to construct an arteriovenous fistula, though it has a problem of stenosis. It is considered to be caused by the influence of wall shear stress on the blood vessel wall. Recently, the influence of flow disturbance is also focused on as one of the causes, and is usually evaluated by the indexes such as TAWSS, transWSS, OSI and RRT. However, the correspondence of these indexes to the characteristic of flow disturbance is not clear. In the present study, these indexes are investigated with two different turbulence intensities, one is composed of fluctuation from the time averaged velocity, and the other is from the phase (ensemble) averaged velocity. As a result, it was found that TAWSS could estimate the extent of pulsatile flow unsteadiness, but the flow disturbance could not. TransWSS could evaluate the intensity of flow disturbance, only under the condition of high correlation between fluctuating velocity perpendicular to the main-flow and that parallel to the main-flow. Therefore, we formulated a new index capable of evaluating the disturbance with any characteristics. The new index shows reasonable performance for the purpose, althought it requires further improvement such as a formulation without post-processing using historical data.