title: Risks and benefits of shunting in carotid endarterectomy. The International Transcranial Doppler Collaborators.
abstract: OBJECTIVE
  Controversy continues about the pathogenesis of perioperative stroke in carotid endarterectomy and the use of shunting. The purpose of this study was to determine, using transcranial Doppler ultrasonography, the severity of ischemia during clamping of the carotid artery as a basis for analysis of complications in patients operated on with and without shunting.
  
  
  METHODS
  In a retrospective study, 11 centers contributed 1,495 carotid endarterectomies monitored with transcranial Doppler. The cases were divided into groups with severe, mild, and no ischemia, and each group was subdivided according to shunt use. The perioperative rate of severe stroke attributable to intraoperative ischemia, in addition to total perioperative stroke, was determined for each subgroup.
  
  
  RESULTS
  Severe ischemia occurred in 7.2% of our cases but cleared spontaneously in about half of these. In those with persisting ischemia the rate of severe stroke was very high, while shunting protected against stroke in such cases. If ischemia did not occur, the stroke rate was higher with shunting, although not so high as in unshunted cases with severe ischemia. Slightly more than one third of the severe strokes were due to postoperative cerebral hemorrhage or carotid thrombosis, unrelated to clamp-induced ischemia or shunting.
  
  
  CONCLUSIONS
  Carotid endarterectomy complications might be reduced by selectively shunting only for severe persisting ischemia. Monitoring of cerebral ischemia would be essential to selective shunting.
authors.affiliation: Neurologic Institute, New York, NY 10032-2603.
authors.forename: J H
authors.initials: JH
authors.lastname: Halsey
mesh_terms: D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000601:surgery; D002339:Carotid Arteries / Q000601:surgery*; D002561:Cerebrovascular Disorders / Q000209:etiology; D004691:Endarterectomy / Q000009:adverse effects / Q000379:methods*; D005069:Evaluation Studies as Topic; D006801:Humans; D008991:Monitoring, Physiologic; D011183:Postoperative Complications / Q000517:prevention & control*; D012189:Retrospective Studies; D012307:Risk Factors; D014463:Ultrasonography