Is a single preoperative duplex scan sufficient for planning bilateral carotid endarterectomy?

Purpose: Duplex scanning is often the sole imaging study before carotid end arterectomy (CEA). Patients with bilateral severe internal carotid artery ( ICA) stenosis may be considered for bilateral CEA. High-grade ICA stenosis, however, may artifactually elevate velocity measurements used to quantify stenosis in the contralateral ICA. It is unknown whether ipsilateral CEA wi ll influence duplex determination of the presence of a contralateral 60% to 99% ICA stenosis. This study was performed to determine whether a single p reoperative duplex scan is sufficient to plan bilateral CEA. Methods: Preoperative and early postoperative carotid duplex scans in patie nts with bilateral ICA stenosis who underwent unilateral CEA were reviewed. Changes in duplex scans that determined stenosis in the ICA contralateral to the CEA were analyzed. Previously validated criteria used to determine 6 0% to 99% ICA stenosis were a peak systolic velocity (PSV) of 260 cm/sec or more combined with an end diastolic velocity (EDV) of 70 cm/sec or more. Results: Over an 8-year period, 460 patients underwent CEA; 107 patients (2 3.3%) had an asymptomatic 50% to 99% contralateral ICA stenosis by standard criteria (PSV, >125 cm/sec) and an early postoperative duplex scan examina tion. Of these 107 patients, 38 patients (35.5%) had duplex scan criteria f or 60% to 99% contralateral ICA stenosis. In these 38 patients, there was a mean postoperative PSV decrease of 47.7 cm/sec (10.1%) and a mean EDV decr ease of 36.0 cm/sec (19.3%) in the ICA contralateral to the CEA. Eight of 3 8 (21.1%) preoperative contralateral 60% to 99% ICA lesions were reclassifi ed as less than 60% on postoperative duplex scanning. Six of 69 (8.7%) preo perative lesions of less than 60% were reclassified as 60% to 99% on postop erative duplex scan. These six preoperative examinations were all close to the criteria for 60% to 99% stenosis (mean PSV, 232.5 cm/sec; mean EDV, 62. 5 cm/sec). Conclusion: One-fifth of patients with apparent 60% to 99% contralateral IC A lesions before the operation have less than 60% stenosis when restudied w ith duplex scan after unilateral CEA. Lesions below but near the cutoff for 60% to 99% may be reclassified as 60% to 99% on the postoperative duplex s can. These findings mandate that when duplex scanning is used as the sole i maging modality before CEA, patients with severe bilateral carotid stenosis must have an additional carotid duplex examination before operation on the second side.