Other flow patterns emerge with a critical stenosis. The red blood cells pass through the narrowed segment and vortices form distal to the stenosis causing areas of flow reversal where the vessel has returned to its normal diameter.

However one should be aware that flow reversal can occur in normal vessels as well. It has been well documented that an area of flow reversal occurs at the normal carotid artery bifurcation. Flow reversal can also occur where branches leave the main vessel at a ninety degree angle.

carotid artery bifurcation