Correlation of intra-arterial contrast stasis with flow patterns at constrictions, branches and bends: an...

Flow patterns at bends and branches have been studied in an easily constructed open channel model so as to determine whether zones of stasis and poor mixing at constrictions, bends and branches can be correlated with certain arteriographic appearances. At bends, spiral flow lines and static zones occur which resemble those seen occasionally in the aortic arch and carotid siphon. At branches, stasis occurs on the outer walls of the branch mouths both in the experiments and arteriography, and constrictions easily produce downstream stasis, previously demonstrated in both arteries and open-channel experiments. Upstream stasis, not previously recorded, can also occur in arteries and model associated with severe constrictions. Occasionally stasis may extend along the whole length of one wall of a vessel when there is a downstream constriction, resembling arteriographic appearances seen in the internal carotid artery in patients with raised intracranial pressure, in those undergoin hyperventilation and also in coronary and other arteries. Despite known rheological differences between blood and water, the experimental findings are thought to be meaningful, and to indicate that there are within arteries, areas where turbulent mixing forces are weak or absent, resulting in arterial stasis.