Angiographic criteria reliably predict when carotid endarterectomy can be safely performed without a shunt

Background: Selective shunting during carotid endarterectomy is widely perf ormed, but the optimal approach for predicting when a shunt is unnecessary remains uncertain. We evaluated the ability of preoperative cerebral angiog raphy to predict when carotid endarterectomy could be safely performed with out a shunt. Study Design: Eighty-seven patients undergoing carotid endarterectomy betwe en August 1991 and December 1997 had preoperative cerebral angiograms. The angiograms were evaluated for the presence of collateral flow from the cont ralateral carotid through the anterior communicating artery and from the po sterior circulation through the posterior communicating artery. Patients th en underwent endarterectomy and were selectively shunted based on somatosen sory evoked potential changes. Internal carotid artery stump pressure was r outinely measured in all patients. Results: Nine patients (10%) had a shunt placed based on somatosensory evok ed potential changes and none of the 87 patients had a perioperative (30 da ys) stroke. Angiography revealed that 36 patients (41%) had no cross-fillin g from the contralateral carotid through the anterior communicating artery. Nine of these patients (25%) required a shunt; none of the 51 patients wit h adequate crossfilling (p < 0.001) did. Furthermore, 94% of the patients w ithout cross-filling but with a patent ipsilateral posterior communicating artery did not require a shunt using somatosensory evoked potential changes as the standard for shunt insertion. Stump pressure measurements (greater than or equal to 25 mmHg) or (greater than or equal to 50 mmHg) did not rel iably exclude the need for a shunt. Only 2 of 15 patients with contralatera l carotid occlusion and 1 of 16 patients with a prior ipsilateral stroke re quired shunts. Conclusions: In the presence of cross-filling from the contralateral caroti d artery, shunt insertion was uniformly unnecessary. In addition, routine s hunting of patients with previous ipsilateral strokes or contralateral caro tid occlusion was not always necessary. Stump pressures were less sensitive than angiographic criteria in determining when a shunt was unnecessary. Ev aluation of cross-filling from the contralateral carotid artery on preopera tive angiography can predict with certainty which patients will not require a shunt. (J Am Coll Surg 1999;189:93-101, (C) 1999 by the American College of Surgeons).