Observations on Simultaneous Internal Carotid Artery and Total Cerebral Blood Flow Measurements in Man

This study examines simultaneous internal carotid artery (ICA) blood flow as measured by the electromagnetic flowmeter (EMF) and total cerebral blood flow (CBF) determined by a nondiffusible dye dilution technique in patients undergoing endarterectomy or carotid ligation for aneurysm. No similar study is available in the literature. In a group of 32 patients having endarterectomy, the pre-endarterectomy ICA-EMF and total CBF values were 110 and 882 ml/min, respectively, and after endarterectomy the respective values were 272 and 1052 ml/min. The preoperative EMF-CBF ratio was 12% and postoperatively it was 26%. A postendarterectomy increase in CBF was observed in all patients, averaging 19% (170 ml/min). There was little difference in the ICA-CBF ratio between those patients with significant contralateral carotid compromise or occlusion and those with normal input (21 vs. 28%). In a group of 12 patients underoing common carotid artery occlusion for an intracranial aneurysm, the blood flow of the ICA was 186 ml/min before occlusion and the simultaneous CBF was 788 ml/min. The EMF to CBF ratio in this group was 24%. In seven patients in whom pre- and postocculsion CBF's were measured, the values were 967 and 794 ml/min, respectively. The decrease in flow of 173 ml/min (18%) was highly significant (p < 0.001). Both acute carotid occlusion and carotid restoration (chronic compromise) result in an approximate change of 19% in total CBF; it may, therefore, be inferred that collateral input does not significantly improve with time and that loss of carotid input produces some degree of permanent hypoperfusion.