The relationship of intraluminal shunting to technical results after carotid endarterectomy. This study evaluates the incidence of defects on the intraoperative angiograms of 160 carotid endarterectomies performed in 146 patients, 81 of 160 (50.6%) with a shunt and 79 of 160 operations (49.4%) performed without a shunt. Angiographic defects were identified in 34 of 160 carotid endarterectomies (21%), of which 21 of 34 (65%) resulted in a greater than 20% stenosis of the internal carotid artery (ICA). There were defects in 6 of 81 (7.4%) shunted vessels compared to 16 of 79 (20%) of those not shunted (p less than 0.05). Thirty-one vessels were reexplored 11 of 81 (13.5%) of those shunted and 20 of 79 (20%) of those not shunted (p less than 0.05). There were four strokes (2.5%) (2 in each group) and one death due to myocardial infarction (0.6%) in the postoperative period. Duplex follow-up from 1-60 months (median 22 months) was available in 114 of 160 (71%) endarterectomies. A stenosis of greater than 50% was detected in 7 of 114 (6%) carotid arteries; 5 of the 7 (71%) were shunted and 2 (29%) were nonshunted. Unrepaired defects were present in 3 of 7 (43%) and no defects in the remaining 4 of 7 (57%) arteries. We conclude that the use of a shunt significantly decreases the number of ICA defects detected angiographically and that immediate revision of demonstrable defects can be undertaken with low morbidity and does not predispose the patient to recurrent stenosis. 