A Longitudinal Assessment of Wall Shear Stress Variation on Arteriovenous Fistula Maturation

Arteriovenous (AV) fistula is the most preferred form of vascular access for end-stage renal disease patients. Acute changes in hemodynamics and in particular wall shear stress (WSS) immediately after fistula placement are followed by the dilation of the vasculature luminal area to recover the normal physiological condition before surgery. However, vasodilation in AV fistula is not well understood and thus, the major goal of this study is to assess the longitudinal effect of wall shear stress on fistula maturation. Six AV fistulae with curved (n = 3) and straight (n = 3) configurations are created between the femoral artery and vein of three Yorkshire pigs. Anatomical configuration and flow measurements are performed at 2D (D: days), 7D, and 28D post-surgery. It is shown that fistulae with relatively higher baseline axial WSS may result in better maturation as compared to the ones with lower levels of baseline axial WSS. This finding is novel and hasn’t been reported in previous studies. Moreover, it is found that the longitudinal variation of WSS is also of high importance in prediction of the maturation of AV fistula. Fistulae whose mean axial WSS decreases over time achieve larger mean area, and therefore, favorable remodeling, while an increasing trend of axial WSS is detrimental to fistulae maturation. Also, it is found that curved fistula as compared to the straight configuration results in larger luminal area over time and thus, is the preferred form of AV fistula.