Does Carotid Endarterectomy Modify Cerebral Vasomotor Reactivity?

Abstract

The effects of carotid endarterectomy (CEA) on cerebral hemodynamics in certain groups of patients with severe carotid stenosis still remain unclear. Cerebral vasomotor reactivity (CVR) is an important indicator of intracranial blood supply and cerebral autoregulation. Symptomatic and asymptomatic patients with severe carotid stenosis and impaired CVR were evaluated before and after CEA. Transcranial Doppler ultrasonography (TCD) and the Diamox test (i.v. administration of 1.0 g acetazolamide) before and 3 months after CEA were performed in 42 patients (21 symptomatic, 21 asymptomatic) with severe (70–99%) carotid stenosis. CVR was assessed as the difference between peak blood flow velocities in the middle cerebral artery ipsilateral to the carotid stenosis before and after acetazolamide injection and as percent increase of blood flow velocity after acetazolamide (ANOVA). Three months after CEA there was statistically significant improvement of CVR in asymptomatic compared with symptomatic patients (p < 0.05, ANOVA). CEA improves CVR mostly in asymptomatic patients. TCD combined with the Diamox test appears to be a useful tool in assessing cerebral hemodynamics prior to carotid surgery, and might be an additional criterion for selecting asymptomatic patients for CEA.

Decreased transcranial Doppler carbon dioxide reactivity is associated with disordered cerebral metabolism in patients with internal carotid artery stenosis

“…[21][22][23][24] Finally, after CEA, the CO 2 reactivity has been shown to increase on both sides, reflecting the improvement of cerebral hemodynamics. 5,[25][26][27] Similar results were found with alternative methods to measure cerebrovascular reserve based on changes in regional cerebral blood flow and/or volume, such as with single-photon emission computed tomography, positron emission tomography, or MRI. [28][29][30] Also, an association was found between a decreased acetazolamide response and the presence of high intensity signals on MRI, especially when located in the centrum semiovale.…”

Cerebral vasomotor reactivity of bilateral severe carotid stenosis: is stroke unavoidable?

“…Our data support the presence of different cerebral hemodynamic features in symptomatic versus asymptomatic patients with bilateral carotid occlusive disease. Based on these data, it may be speculated that patients with carotid stenosis become symptomatic because of their impaired VMR, and that asymptomatic patients remain asymptomatic because of their effective cerebrovascular reserve capacity [30]. In addition, our findings on the VMR of the VA suggest an independent cerebrovascular reserve capacity of posterior circulation in the presence of carotid occlusive disease and a key role for the circle of Willis in intracerebral hemodynamics.…”

Hemodynamic Assessment of Carotid Stenosis by Functional Magnetic Resonance Imaging

“…Other methods of evaluating vasomotor reserve include techniques such as positron emission tomography scans, transcranial Doppler or MRI with the application of acetazolamide [22,23,24]. The disadvantages of these techniques include the invasive character of intravenous applications of nuclides and acetazolamide and the inexact nature of Doppler sonography in the low-flow regions.…”