The accuracy of carotid back pressure as an index for shunt requirements. A reappraisal.

The accuracy of a carotid back pressure obtained to determine the need for an internal shunt has been questioned. Not all patients undergoing carotid endarterectomy require a carotid shunt while clinically significant cerebral ischemia can be prevented by selective use of a carotid shunt. From July 1977 to January 1980,139 carotid endarterectomies were performed under general anesthesia at normal carbia and blood pressure. Indications for these procedures included stroke with maximum recovery (60); transient ischemic attacks (49); asymptomatic lesions (25); and non-lateral izing symptoms (5). Indications for use of a shunt consisted of previous ipsilateral stroke or an internal carotid artery back pressure of less than 25 mm Hg. All operations were performed under general anesthesia, and before carotid clamping 10,000 units of heparin were administered intravenously. On the basis of these criteria, 70 operations were done with a shunt in place, 60 (86%) of which required shunting because of prior cerebral infarction and 10 (14%) for back pressure less than 25 mm Hg. In 60 other operations, no shunts were used because back pressure was greater than 25 mm Hg; in 34 (49%) unshunted patients, back pressure ranged from 25 to 50 mm Hg.