Ageing affects the accuracy of duplex ultrasonography in grading carotid artery stenosis

Duplex ultrasonography is frequently used to select patients who are eligible for carotid endarterectomy by using local blood flow velocities to quantify the degree of internal carotid artery stenosis. However, ageing affects flow velocities and might hence influence the accuracy of duplex ultrasonography, as explored in the present study.

We determined peak-systolic (PSV) and end-diastolic (EDV) blood flow velocities in the common carotid artery (CCA) and internal carotid artery (ICA) in the absence of atherosclerosis and correlated these with age. The established correlation was applied to measurements in the ICA with visualised atherosclerosis to evaluate whether an age-related change in blood flow velocities modified stenosis grading.

In 465 arteries without atherosclerosis, PSV declined linearly in both the CCA (r = -0.55) and ICA (r = -0.44). The EDV decreased linearly in the CCA and ICA (r = -0.61 and r = -0.56, respectively). In 774 internal carotid arteries with atherosclerosis present, the use of an age-dependent reference increased the estimated degree of stenosis in 3 young subjects. The stenosis grade was reduced in 11 older subjects, mainly in symptomatic arteries.

Blood flow velocities in the carotid artery system decrease continuously with increasing age. This may affect the estimated degree of internal carotid artery stenosis in the elderly.