Observations on the flow characteristics of blood flow in arteriovenous fistulae (experimental)

Hemodynamic play a very significant role in the pathophysiology of intracranial arteriovenous malformation. The surgical decisions are based on the understanding of the complexities of the flow. Quantification of the abnormal flow is difficult. The mathematical models provide limited information due to the simplicity of the design of these models. Flow of fluid in a tube is very sensitive to small changes in the diameter. We studied the flow characteristics of a fistula by introducing accurately machined acrylic fistulae between the femoral arteries and veins of dogs. The influences of systemic arterial pressure, diameter of the arterial feeders, volume of blood flow, velocity of flow and the diameter of the shunt on the flow of blood across the shunt were studied. Our experiments suggest that the flow characteristics of an arteriovenous fistulae are complex and are influenced by small changes in the diameters of the fistula and the feeding artery. Our model demonstrates the occurrence of the anomalous flow reduction in the fistula and steal phenomenon and is therefore a more realistic representation of the clinical situation. The design of a mathematical model should include the diameter of the fistula if it is intended to replicate the hemodynamic characteristics of an arteriovenous malformation more faithfully.