Hemodynamics of a simulation of the vertebrobasilar system using silicone tube.

We investigated the hemodynamics of the vertebrobasilar system (VBS) using a simulation model tube made of silicone which had different diameters between the bilateral vertebral artery (VA) ducts (stenotic and normal VA ducts). Using the ultrasonic Doppler method. the laterality index (L.I.) of the flow velocity in the VA duct was 32.88%. The flow volume of the anterior inferior cerebellar artery duct and the posterior inferior cerebellar artery duct also had significant laterality. By investigating the effects of the rotatory pulse rate and fluid viscosity, a maximal decrease to below 40-50% of the flow volume of the branches, and to below 71.93% in the mean flow velocity of the basilar artery (BA) duct (BA duct) were observed. and the maximum L.I. increased to 43.15%. When the unilateral stenotic VA duct was occluded by clamping (clamping occlusion), the flow volume profiles of the branches were the same as without clamping occlusion. The L.I. showed no significant changes and the maximal decrease in the mean flow velocity of the BA duct was 68.61%. Using the laser Doppler method, the flow velocity distribution of the BA duct was shifted towards the side of the stenotic VA duct. These results suggest that the rheological dynamics in the main vessels can certainly reflect the posterior circulatory dynamics, and that modulating factors also aggravate the hemodynamics of the VBS with this disorder.