Monitoring cerebral perfusion during carotid endarterectomy.

Transcranial pulsed Doppler ultrasound was used to monitor blood velocity in the middle cerebral artery (MCA) of two patients during ipsilateral carotid endarterectomy. In the first patient the ultrasound data demonstrated a non-functioning shunt which was corrected by repositioning the distal end of the shunt. In the second patient MCA blood velocity data demonstrated that clamping of the external carotid artery would have resulted in complete cessation of MCA flow throughout endarterectomy. These cases illustrate the benefit that this technique offers to the individual patient undergoing carotid surgery.