Duplex carotid sonography in distinguishing acute unilateral atherothrombotic from cardioembolic carotid artery occlusion.

PURPOSE To distinguish between acute complete unilateral cardioembolic and atherothrombotic internal carotid artery (ICA) occlusion by using duplex carotid sonography. METHODS We studied 11 patients with cardioembolic ICA occlusion (CE group), 32 patients with atherothrombotic ICA occlusion (AT group), and 25 patients with normal angiographic findings (control group). We obtained B-mode scans and measured the end-diastolic flow velocity (EDV) in both common carotid arteries within 3 days of the onset of symptoms. Side-to-side ratios of EDV (ED ratio) were calculated by dividing the flow velocity on the unaffected side by that on the affected side. RESULTS In the AT group, the proximal ICA was full, with a large area of heterogeneous and partially calcified plaque, and the EDV (10.9 +/- 6.1 cm/s) was significantly lower than that in the control group (20.3 +/- 6.0 cm/s). The ED ratio was greater than 1.4 in all but one patient. In three patients in the CE group, B-mode scans showed a mobile, echogenic intravascular structure in the proximal ICA. The EDV (1.8 +/- 3.4 cm/s) was significantly lower than that in the control and AT groups. The ED ratio was greater than 1.4 in all cases. CONCLUSION We conclude that B-mode scans and the EDV in the common carotid artery can help to distinguish between acute cardioembolic and atherothrombotic ICA occlusion.