Minimizing the risks of carotid endarterectomy.

In 1971 this study was undertaken to determine optimal methods and guidelines for lowering the mortality and neurologic complication rates associated with carotid endarterectomy. Of 570 carotid endarterectomies, 481 (84%) were performed under local anesthesia to provide continuous neurologic monitoring and to permit operation on the very elderly and poor-risk patient. In 418 of these procedures carotid stump pressures (CSPs) were measured with patients awake to determine the level of back pressure sufficient for brain protection during operative occlusion. Selective shunting was necessary in 40 (8%) of these cases. Of 78 patients with a CSP of 0 to 25 mm Hg, only 39 (50%) required shunting. Only one patient with a pressure greater than 25 mm Hg (29 mm Hg) needed a shunt. The CSP/brachial blood pressure (BBP) index was calculated for 410 procedures. Of 97 patients with a CSP of 0 to 30 mm Hg, only 31 required a shunt (CSP/BBP index 0.01 to 0.18). No shunt was necessary for an index greater than 0.18. Patients with a contralateral occlusion or severe stenosis required a shunt six times more frequently than those with unilateral disease. For 570 procedures the overall mortality rate was 0.7% and the neurologic complication rate was 0.9%. When local anesthesia was used for 481 procedures, there was only one death (0.2%). For 74 asymptomatic lesions there were no deaths or stroke. Neurologic monitoring under local anesthesia and CSPs are reliable indicators for selective shunting. Multiple-risk factors influence the outcome of carotid endarterectomy, but most can be avoided.