Computational analysis of turbulent haemodynamics in radiocephalic arteriovenous fistulas with different anastomotic angles
Saturday 9th February 2019
Prouse, G.; Stella, S.; Vergara, C.; Engelberger, S.; Trunfio, R.; Canevascini, R.; Quarteroni, A.; Giovannacci, L.
ABSTRACT Objective: Hemodynamics has been known to play a major role in the development of intimal hyperplasia (IH) leading to arteriovenous fistula failure. The goal of our study is to investigate the influence of different angles of side-to-end radiocephalic anastomosis upon the hemodynamic parameters that promote intimal dysfunction and therefore IH. Methods: Realistic 3D meshes were reconstructed using ultrasound measurements from distal side-to-end radiocephalic fistulas. The velocity at the proximal and distal radial inflows and at specific locations along the anastomosis and cephalic vein was measured through single examiner duplex ultrasound. A computational parametric study, virtually changing the inner angle of anastomosis, was performed. For this purpose we used advanced computational models that include suitable tools to capture the pulsatile and turbulent nature of the blood flow found in arteriovenous fistulas. The results were analysed in terms of velocity fields, wall shear stress distribution and oscillatory shear index (OSI). Results: Results show that the regions with high OSI, that are more prone to the development of hyperplasia, are greater and progressively shift toward the anastomosis area and the proximal vein segment with the decrease of the inner angle of anastomosis. Conclusions: The results of this study show that inner anastomosis angles approaching 60°-70° seem to yield the best hemodynamic conditions for maturation and long term patency of distal radiocephalic fistulas. Inner angles greater than 90°, representing the smooth loop technique, did not show a clear hemodynamic advantage.