PREDICTING THE EFFECT OF CAROTID-ARTERY OCCLUSION DURING CAROTID ENDARTERECTOMY - COMPARING TRANSCRANIAL DOPPLER MEASUREMENTS AND CEREBRAL-ANGIOGRAPHY

Background and Purpose-We correlated the mean transcranial Doppler blo od flow velocity (FVm) during carotid endarterectomy with the function al collateral pathway(s) documented by angiography. Methods-Three pati ent groups were established: group 1 was dependent on the anterior com municating artery, group 2 on the anterior communicating artery and ip silateral posterior communicating artery, and group 3 on the ipsilater al posterior communicating artery. Continuous middle cerebral artery F Vm and electroencephalosraphic monitoring were performed in 45 patient s during carotid endarterectomy. Results-Clamped FVm was lowest in gro up 3 at 17+/-9 cm/s versus 36+/-16 and 33+/-11 cm/s for groups 1 and 2 (P<0.01). FVm values in groups 1 and 2 were similar. There was signif icant cerebral arterial vasodilation in group a patients on the basis of a pulsatility index of 0.38+/-0.15. The maximum FVm after clamp rel ease was similar among the 3 groups. Normalized blood flow velocity 1 minute before release of the clamp was increased from the minimum flow velocity after clamping only in group 1 and 2 patients. Conclusions-T he ipsilateral posterior communicating artery is a minor collateral pa thway during acute carotid occlusion that contributes little to the co llateral flow if there is a functional anterior communicating artery. Collateral flow through the middle cerebral artery is not recruited du ring occlusion in group 3 patients. The reperfusion FVm transient is i ndependent of the primary collateral pathway. Documentation of functio nal collateral pathways on the basis of Doppler or angiographic examin ation may be advantageous in future studies since it can provide the b asis for comparison among studies.