Critical appraisal of the application of carotid duplex scanning

To evaluate the indications for carotid arterial imaging in an open access vascular laboratory. To identify those symptoms predictive of > 50% stenosis of the carotid artery in order to reduce unnecessary imaging. To test the hypothesis that duplex scanning would not be of significant benefit in the management of those patients with ill defined symptoms.

We compared the outcome of carotid duplex scanning performed on 816 consecutive patients referred for a variety of clinical indications. The medical records of 816 patients were retrospectively analysed to identify the clinical indication for carotid duplex imaging over a three-year period (1997-9).

The indications for duplex imaging were divided into two groups: definite carotid symptoms, n=350 (transient ischaemic attack n=205, cerebrovascular accident n=66, amaurosis fugax n=49, dysphasia n=30); and non-carotid symptoms, n=466 (dizziness n=63, syncope n=63, confusion n=20, vertigo n=10 and others n=310). Less than 5% of those with definite carotid symptoms and 2% of those with ill-defined symptoms had a stenosis > 80%.

Regardless of symptoms, 14% and 2.9% of patients referred for carotid duplex imaging have a stenosis of > or = 50% and > or = 80%, respectively. Patients without definite carotid symptoms are of low priority for duplex imaging.