Direction of Blood Flow in the Internal and External Carotid Arteries Following Occlusion of the Ipsilateral Common Carotid Artery

Abstract

ECENT studies by Hardesty et al. 3,~ using an electromagnetic flowmeter have shown that in a number of patients there is a reversal of the direction of blood flow in the internal carotid artery following complete occlusion of the ipsilateral common carotid artery. This finding, first predicted by Sweet and associates 9,1~ on the basis of differentials in intravascular pressure in the internal and external carotid arteries following proximal occlusion, refutes the contention that the flow of blood is from external to internal carotid following occlusion of the ipsilateral common carotid artery. However, there have been no studies in which the actual measurement of flow in the external-internal carotid system was correlated with reduction of pressure in these two vessels following proximal occlusion. The present study was undertaken in an effort to determine the relationship between intravascular pressure and the direction of flow in the internal carotid following complete occlusion of the common carotid artery. In addition, an attempt was made to correlate the direction of flow with the degree of cross-filling of the intracranial circulation as determined by carotid arteriography during compression of the contralateral carotid artery.