Long-Term Hemodynamic Effects of Carotid Endarterectomy

Abstract

Background and Purpose-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. Methods-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 (Ͼ70%) 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. Results-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. Conclusions-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. (Stroke. 1998;29:1567-1572.)

Optimal Location for Arterial Input Function Measurements near the Middle Cerebral Artery in First-Pass Perfusion MRI

“…These parameters enable the identification and characterization of pathologic areas in brain tissue. Perfusion-weighted imaging can identify tissue at risk of infarction in stroke patients, facilitate grading and delineation of brain tumors, and can provide important hemodynamic information in, for example, Alzheimer's disease, obstructive cerebrovascular disease and migraine (Hakyemez et al, 2006;Harris et al, 1998;Kluytmans et al, 1998;Sorensen et al, 1999).…”

Cerebral Hemodynamics in Asymptomatic and Symptomatic Patients With High-Grade Carotid Stenosis Undergoing Carotid Endarterectomy

“…10 It may also improve the hemodynamic state, as suggested by postoperative improvement in cerebrovascular reactivity and cerebral blood flow (CBF). 7,[11][12][13][14] Several studies including both symptomatic and asymptomatic subjects with CS have detected hemodynamic improvement after CEA, [12][13][14][15] but some findings suggest differences in hemodynamics between these populations. 6,16 Dynamic susceptibility contrast MRI (DSC-MRI) utilizes rapid collection of the MR signal during the passage of a paramagnetic contrast agent bolus through the brain.…”

Functional MR Imaging in Patients with Carotid Artery Stenosis before and after Revascularization

“…Some authors report its achievement after 3 hours, 21 others report 2-6 months. 3,34 These multiple influencing factors and the relatively small sample size, especially in the subgroup analyses, as well as subtle differences in performance pre-and postsurgically, may also explain the relatively high SDs in our patient group. A more direct way to measure CVR is via breathing an enriched CO 2 gas, which will allow a more controlled and standardized measurement of the CVR in patients irrespective of their task performance.…”