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Risks and benefits of shunting in carotid endarterectomy. The International Transcranial Doppler Collaborators
1Neurologic Institute, New York, NY 10032-2603.
Insights
Selective shunting during carotid endarterectomy for severe, persistent ischemia can reduce stroke risk. Monitoring cerebral ischemia is crucial for this approach to minimize perioperative complications.
Area of Science:
- Neurology
- Vascular Surgery
- Medical Imaging
Background:
- The cause of perioperative stroke after carotid endarterectomy and the role of shunting remain debated.
- Transcranial Doppler (TCD) ultrasonography can assess cerebral ischemia during carotid clamping.
Purpose of the Study:
- To evaluate the severity of cerebral ischemia during carotid artery clamping using TCD.
- To analyze perioperative stroke complications in patients undergoing carotid endarterectomy with and without shunting.
Main Methods:
- Retrospective analysis of 1,495 carotid endarterectomies from 11 centers.
- Cases categorized by ischemia severity (severe, mild, none) and shunt use.
- Perioperative stroke rates determined for each subgroup, distinguishing clamp-induced ischemia from other causes.
Main Results:
- Severe ischemia occurred in 7.2% of cases, resolving spontaneously in about half.
- Persisting severe ischemia was associated with a very high stroke rate, significantly reduced by shunting.
- In the absence of ischemia, shunting was linked to a higher stroke rate compared to unshunted cases.
- Over one-third of severe strokes were unrelated to clamp-induced ischemia (e.g., hemorrhage, thrombosis).
Conclusions:
- Selective shunting for severe, persistent ischemia during carotid endarterectomy may decrease complications.
- Continuous monitoring of cerebral ischemia is essential for guiding selective shunting decisions.
Background And Purpose:
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.