Modeling and Simulation of Blood Flow Past the Distal Anastomosis of the Arteriovenous Graft for Hemodialysis
Hemodialysis is a common treatment for ESRD patients to manage their chronic renal failure while awaiting kidney transplant. Arteriovenous graft is a major vascular access for hemodialysis but often fails due to the thrombosis close to the anastomosis. Most of existing computational models employ an unrealistic rigid model assuming the vein and graft are rigid. And some of the existing results are inconsistent in characterizing the flow and force fields. We introduce a new three-dimensional computational model that incorporates the vein and graft deformability. The new model is based on the lattice Boltzmann-immersed boundary (LB-IB) framework for handling the fluid-flexible-structure interaction. We extend the framework to the case of non-uniform mesh, including generation of the non-uniform mesh and force computing on the non-uniform mesh. Numerous simulations are designed and conducted with various combinations of different model parameters. Our results suggest that: 1) the deformability has significant influence on the flow and force fields of blood flow through vein-graft anastomosis. The WSS, WSSG, WNSG, and their averaged values are significantly lower than the rigid case; 2) the effects of flow pulsatility, AVG-vein diameter ratio, AVG attaching angle, and Reynolds number are less pronounced in the deformable case than the rigid case; 3) the averaged WSS, WSSG, and WNSG are significantly greater on the graft wall than on the vein wall; 4) the implantation of graft dramatically increases the averaged WSS, WSSG, and WNSG on the vein wall. The major contributions of the dissertation are as follows: 1) introduction of a new 3D computational model for blood flow through the distal AVG anastomosis; 2) non-uniform mesh generation for the vein-AVG anastomosis by elastic fibers and fluid-solid force computation on the non-uniform mesh; 3) identification of the effects of various model parameters on the flow and force fields, in particular, the role of vein and graft deformability on the flow and force fields.
Zhu, Purdue University.
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