Static zones in the internal carotid artery: correlation with boundary layer separation and stasis in model flows

Abstract

In a divergent flow, failure of the boundary-layer particles to proceed with the main flow against an adverse pressure gradient may cause them to slow down and reverse their direction of flow. If this occurs the main flow stream separates from the wall of the vessel, and a stagnant (or static) zone of fluid is formed against the vessel wall. The exact site of these static zones can be demonstrated in model flows, and evidence is presented here of stasis at a Y junction in both open and closed-channel flows. Similarly, stasis of contrast medium occurs in the internal carotid artery in some patients. Whereas this stasis extends widely along the length of the artery where the flow in the vessel is slowed due to raised intracranial pressure, in patients with signs and symptoms of cerebrovascular disease the stasis occurs at the origin of the vessel and the adjacent parts of the carotid artery.