Cerebral Autoregulation and Blood Flow Redistribution in the Precerebral Arteries in Patients with Carotid Artery Occlusion

Abstract

Abstract Background: State of cerebral autoregulation and changed blood flow in the precerebral arteries can serve as selection criteria in favor of extra-intracranial bypass surgery and as a prediction factor in patients with carotid artery occlusion. However, information capacity of quantitative values of this functional state of the brain circulation has not been studied well enough. Objective: The objective is to assess the state of cerebral autoregulation and blood flow redistribution in the precerebral arteries in patients with carotid artery occlusion. Material and Methods: The study involved 24 patients aged 41 to 80 with carotid artery occlusion. Eight of them were asymptomatic. We measured blood flow velocity in intracranial arteries by using transcranial Doppler (MultiDop X) and flow velocity index in precerebral arteries - by using duplex scanning (Vivid e). Cerebral autoregulation was evaluated with cross-spectral analysis of spontaneous oscillations of blood pressure (CNAP, Austria) and blood flow velocity within the range of Mayer’s waves (80-120 mHz). Results: In most symptomatic patients the cerebral autoregulation decreased on both sides (0.3±0.3 rad ipsilaterally and 0.6±0.4 rad contralaterally). There was no cerebral autoregulation impairment in all asymptomatic patients (1.1±0.5 rad ipsilateral and 1.3±0.5 rad contralateral). We noticed an increased blood flow index in the contralateral internal carotid artery (312±113 ml/min) and ipsilateral vertebral and external carotid arteries (126±64 ml/min and 158±72 ml/min, respectively). Conclusion: A comprehensive analysis of cerebral autoregulation and blood flow in the precerebral arteries helps to identify the extent of cerebral hemodynamics compensation in carotid artery occlusion, which can classify patients in need of revascularization surgery. Keywords Blood flow index; Carotid artery occlusion; Cerebral autoregulation; Cerebrovascular reserve; Extra-intracranial bypass surgery