Bubble motion in a blood vessel: shear stress induced endothelial cell injury.

Mechanisms governing endothelial cell (EC) injury during arterial gas embolism have been investigated. Such mechanisms involve multiple scales. We have numerically investigated the macroscale flow dynamics due to the motion of a nearly occluding finite-sized air bubble in blood vessels of various sizes. Non-Newtonian behavior due to both the shear-thinning rheology of the blood and the Fahraeus-Lindqvist effect has been considered. The occluding bubble dynamics lends itself for an axisymmetric treatment. The numerical solutions have revealed several hydrodynamic features in the vicinity of the bubble. Large temporal and spatial shear stress gradients occur on the EC surface. The stress variations manifest in the form of a traveling wave. The gradients are accompanied by rapid sign changes. These features are ascribable to the development of a region of recirculation (vortex ring) in the proximity of the bubble. The shear stress gradients together with sign reversals may partially act as potential causes in the disruption of endothelial cell membrane integrity and functionality.