The Hemodynamic Effects of Internal Carotid Artery Stenting: A Study with Color-Coded Duplex Sonography

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Background: Stenting has been used as an alternative treatment for patients with internal carotid artery (ICA) stenosis. Color-coded duplex sonography (CDS) is able to measure not only the prestenting stenosis but also the poststenting hemodynamic changes. The purpose of this study was to quantify, using CDS, the hemodynamic changes after ICA stenting. Methods: Both symptomatic and asymptomatic patients were included in this study. The degree of ICA stenosis before stenting was required to be more than 50%. Thirty-two treated ICAs were included to compare the prestenting and poststenting CDS findings, including the diameter and cross-sectional area of the lumen, the flow peak systolic and end-diastolic velocities, the resistivity index and the amount of flow in bilateral extracranial carotid and vertebral arteries. Results: After stenting, the turbulent flow pattern in the stenotic ICA recovered to laminar flow, and the reversed ophthalmic flow direction normalized. Of the CDS parameters applied to evaluate the effect of stenting on ICA stenosis, the diameter, residual area, peak systolic velocity, diastolic velocity and the ration of systolic flow velocity ratio in the ICA to that in the common carotid artery (CCA) were altered significantly. The mean area and residual area of these stenotic ICAs showed increases of 24% (p = 0.005) and 84% (p = 0.001) after ICA stenting, respectively. The mean peak systolic flow velocity significantly decreased by 71%. The mean diastolic flow velocity also significantly decreased (by 77%). Both the systolic and diastolic velocities of the ipsilateral CCA significantly increased after stenting. The amount of flow in the contralateral ICA decreased significantly after stenting. The change in the amount of flow in the vertebral arteries after ICA stenting was insignificant. Conclusions: The results of this CDS study clearly demonstrated the hemodynamic changes after ICA stenting. The carotid stenting significantly changed the ICA flow pattern, diameter, residual area, peak systolic velocity and ICA to CCA velocity ratio.