Influence of the status of the contralateral carotid artery on the outcome of carotid surgery

From 1985 to 1995, 747 carotid arteries were operated on in 694 patients, who were under general anesthesia and continuous electroencephalogram (EEG) monitoring. These patients were divided into three groups according to contralateral carotid status. Group 1 consisted of 58 patients who had contralateral occlusion; group 2, 53 patients who had contralateral stenosis and bilateral staged surgery; and group 3, 583 patients who had nonstenotic contralateral internal carotid artery. All groups were similar with regard to age and sex ratio. There were more asymptomatic patients in group 3 than in group 1 (39.9% vs. 25.8%) (p < 0.05), and less preoperative strokes in group 2 than in the other groups (3.7% vs. 17.2% and 13.6%, respectively) (p < 0.05). Among risk factors, smoking was less frequent in group 3 (59.5%) than in group 1 (82.7%) and group 2 (77%) (p < 0.01), and coronary artery disease was more frequent in group 2 (60%) than in group 1 (32.7%) and Group 3 (26.4%) (p < 0.01). EEG changes occurred more frequently in group 1 (25.8%) than in group 2 [5.6% (first stage) and 3.8% (second stage)] and in group 3 (4.9%) (p < 0.01). A shunt was used only when EEG changes did not disappear after pharmacologic increasing of central blood pressure, which occurred more frequently in group 1 (10.3%) than in group 2 (0%) and group 3 (0.3%) (p < 0.05). The combined morbidity/mortality rate was similar for groups 1 and 3 (1.7% and 1.5%, respectively), however, transient morbidity was more frequent in group 1 (6.9%) than in group 3 (1.5%) (p < 0.05). The combined morbidity/mortality rate was higher in group 2 than in group 3 (7.5% vs. 1.5%) (p < 0.05), and all strokes in group 2 were seen during the second-stage operation. In conclusion, contralateral carotid artery occlusion had minimal influence over carotid surgery results. Selective use of a shunt based on EEG monitoring prevented ischemic strokes, with minimal neurologic morbidity. Contralateral carotid stenosis did not affect operative strategy for first stage, but we noted a higher incidence of strokes during the second procedure.