Effect of contralateral disease on duplex measurements of internal carotid artery stenosis

• Published in: British journal of surgery 2000-08, Vol.87 (8), p.1057-1062
• Main Authors: Ray, S. A., Lockhart, S. J. M., Dourado, R., Irvine, A. T., Burnand, K. G.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Biological and medical sciences; Blood Flow Velocity; Cardiovascular system; Carotid Artery, External - physiopathology; Carotid Artery, Internal - physiopathology; Carotid Stenosis - diagnostic imaging; Carotid Stenosis - physiopathology; Endarterectomy, Carotid - methods; Female; Hemodynamics - physiology; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Neurology; Postoperative Care; Preoperative Care; Recurrence; Ultrasonic investigative techniques; Ultrasonography, Doppler, Duplex - methods; Vascular diseases and vascular malformations of the nervous system
• ISSN: 0007-1323; 1365-2168
• DOI: 10.1046/j.1365-2168.2000.01492.x

Background Duplex ultrasonography is increasingly used as the sole method of imaging before carotid endarterectomy. This study investigated the measured degree of stenosis in the contralateral carotid artery before and after operation. Methods Duplex‐derived peak systolic velocity (PSV), end‐diastolic velocity (EDV) and internal carotid artery/common carotid artery (ICA/CCA) velocity ratios were measured in the contralateral unoperated ICA before 131 consecutive unilateral endarterectomies and compared with preoperative angiographic findings. Three months later duplex scans were repeated to assess whether there had been any alteration in the severity of the stenosis in the contralateral unoperated artery. Results Bilateral ICA disease (greater than 50 per cent stenosis) was present in 50 patients (38 per cent). Three months after operation, ultrasonography of the 105 unoperated, patent, contralateral arteries showed a decrease in mean(s.d.) PSV (1·21(0·83) versus 1·07(0·69) m/s; P < 0·01) and EDV (0·41(0·29) versus 0·35(0·24) m/s; P < 0·01). This resulted in 14 (42 per cent) of 33 patients with contralateral disease being downgraded to a less severe category of stenosis. Use of the ICA/CCA velocity ratio prevented overestimation in eight of the 14 patients, while preoperative angiography correctly classified 13 of the 14 patients. Conclusion Bilateral carotid artery disease can cause overestimation of the severity of stenosis by duplex ultrasonography if absolute velocity is used as the main criterion. © 2000 British Journal of Surgery Society Ltd