Simulation of blood flow past distal arteriovenous-graft anastomosis with intimal hyperplasia

Late-stage kidney disease patients have to rely on hemodialysis for the maintenance of their regular lives. Arteriovenous graft (AVG) is one of the commonly used devices for dialysis. However, this artificially created shunt may get clotted and eventually causes the dialysis to fail. The culprit behind the AVG clotting and failure is the intimal hyperplasia (IH), the gradual thickening of vein-wall in the vicinity of the blood vessel-graft conjunctions. The mechanism of IH is not well understood despite extensive studies. In this work, we investigate the effects of the IH development, including its location and severity on the flow and force fields in the distal AVG anastomosis using computational fluid dynamics. The stenosis due to IH is modeled in the shape of a Gaussian function with two free parameters. The blood is modeled as a viscous incompressible fluid, and the blood flow (pulsatile) is governed by the Navier–Stokes equations which are numerically solved by the lattice Boltzmann model (D3Q19). The fluid-structure interaction is modeled by the immersed boundary framework. Our computational results show that the IH severity has the most significant influences on the wall shear stress, wall-normal stress, and the axial oscillating index. The stenosis location and flow pulsatility do not have pronounced effects on flow and force fields. Our results indicate that the IH progression tends to exacerbate the disease and accelerate the closure of the vein lumen, and hence the dialysis failure