Long-term hemodynamic effects of carotid endarterectomy.

Abstract

The presence and importance of hemodynamic factors to the beneficial effect of carotid endarterectomy (CEA) in patients with severe stenosis of the internal carotid artery (ICA) is unclear. The purpose of this study was to investigate possible hemodynamic changes caused by a severe ICA stenosis and the subsequent changes after CEA. Hemodynamic parameters were acquired with dynamic susceptibility contrast MRI. Regional cerebral blood volume (rCBV), mean transit time (MTT), time of appearance, and time to peak were determined in 19 patients with severe stenosis (>70%) of the ICA before and after CEA and in 33 control subjects. Four patients had an occlusion of the contralateral ICA. Corresponding T2-weighted MRI and inversion recovery MRI scans were used for segmentation of gray and white matter regions. In the hemisphere ipsilateral to the stenosed ICA, no significant differences were found for the rCBV or MTT between patients and control subjects. Also, no significant alterations in these two parameters were observed after CEA. In the hemisphere contralateral to the stenosed ICA, hemodynamic changes were observed only in patients with an ICA occlusion contralateral to the stenosed ICA. In these patients, rCBV, MTT, time of appearance, and time to peak were all increased in the contralateral hemisphere. After CEA, all hemodynamic parameters fell in the normal range. Although CEA does improve the cerebral circulation in patients with a severe stenosis and a contralateral ICA occlusion, the hemodynamic effects of CEA in patients with severe stenosis without a contralateral ICA occlusion are negligible.