The Pruitt-Inahara shunt maintains mean middle cerebral artery velocities within 10% of reoperative values during carotid endarterectomy

Objective: The purpose of this study was to assess the ability of the Pruit t-Inahara shuns to maintain adequate middle cerebral artery velocities duri ng carotid endarterectomy. Study design: Prospectively collected data recorded during 548 carotid enda rterectomies performed at a single university hospital were analyzed to loo k at changes in cerebral blood flow velocities at different stages during t he procedure. Parallel data relating to blood pressure and end-tidal carbon dioxide were also examined. Results: During the first carotid artery cross damp, middle cerebral artery velocity fell by 42%. A total of 169 patients (31%) had velocities that fe ll below 15 cm/s (electrical activity in the brain becomes altered below th is level). After shunt insertion, only 2% of patients had middle cerebral a rtery velocities less than 15 cm/s. In only one patient was the velocity le ss than 10 cm/s. Increased systolic or diastolic blood pressure raised flow through the shunt significantly (P = .001). When two criteria used for sel ective shunt use were compared, only a moderate correlation was found betwe en absolute middle cerebral artery velocity after carotid cross clamping an d percentage change in middle cerebral artery velocity relative to preclamp values. Conclusions: The Pruitt-Inahara shunt is able to maintain adequate middle c erebral artery velocity in 98% of patients undergoing carotid endarterectom y. Alterations in blood pressure can significantly affect flow through the shunt. (J Vasc Surg 2000; 32:299-306.).