Intraoperative regional cerebral blood flow during carotid endarterectomy.

Regional cerebral blood flow (rCBF) during internal carotid artery (ICA) occlusion for endarterectomy can be measured without inconvenience using the probe holder illustrated. When mean ipsilateral hemispheric CBF exceeds 20 ml/100 gm/min, an intraluminal bypass is not necessary (63% of patients), except in patients with extensive cerebrovascular disease in whom rCBF should also exceed 20 ml/100 gm/min in all areas. ICA "stump" pressure is falsely high in about 20% of patients, and is therefore not a dependable criterion for selecting patients who need shunting. While intraoperative shunting is capable of restoring pre-occlusion CBF levels, it does not eliminate the risk of intraoperative ischemic neurological deficit of probable embolic origin.