Contribution of inflow artery to observed flow in a vascular access: A computational fluid dynamic modeling study of an arteriovenous fistula circuit.

Introduction: The volume of blood flowing through the vascular access is an important parameter necessary to provide adequate dialysis for a functional arteriovenous fistula. Higher blood flows are seen in arteriovenous access that receive inflow from larger arteries such as brachial or axillary compared to those based on medium-caliber radial or ulnar arteries. We hypothesized that an anatomic difference in the length and the diameter of the artery is an important determinant of the flow volume in arteriovenous fistula created at different anatomic locations.

Methods: Using computational fluid dynamics, we evaluated the contribution of the length and diameter of inflow artery on simulations performed with geometric models constructed to represent arteriovenous fistula circuits. Lengths and diameters of the inflow artery were altered to mimic arteriovenous fistula created at various locations of the upper extremity with standard and variant anatomy.

Results: Models of arteriovenous fistula created with variable lengths and diameters of the inflow artery suggest that the length of the vessel has an inverse linear relationship and the diameter has a direct linear relationship to flow volume.

Conclusion: Computational fluid dynamic modeling of arteriovenous fistula can be used to understand the physiologic basis of clinical observations of function. Evaluation of the effect of inflow artery length and diameter helps explain the higher flows seen in arteriovenous fistula created using large caliber arteries for inflow. Computational fluid dynamic modeling helps operators understand the contributions of inflow artery in access function and can guide anastomotic site selection.