Cerebral autoregulation and blood flow distribution in the precerebral arteries for determining indications of extra-intracranial bypass in patients with carotid artery occlusion

Background. Prevention of ischemic stroke in patients with carotid artery occlusion is conventionally associated with performing cerebral revascularization. However, determining the indications for it is still an actual problem. The informative value of noninvasive assessment of cerebral autoregulation and blood flow distribution in the precerebral arteries in patients with carotid artery stenosis is shown. At the same time, in patients with carotid artery occlusion, these indicators have been studied to a lesser extent. Aim. To evaluate the informative value of cerebral autoregulation and blood flow distribution in the precerebral arte ries for determination the indications of extra‑intracranial bypass in patients with carotid occlusion. Materials and methods. 54 patients (aged from 41 to 83 y. o.) with carotid artery occlusion were studied. Blood flow velocity in intracranial arteries was determined with transcranial Doppler (system Multi‑Dop X), whereas flow velocity index in precerebral arteries – with duplex scanning (system Vivid Е). Cerebral autoregulation was assessed based on phase shift between spontaneous oscillations of blood flow velocity in basal cerebral arteries and systemic blood pressure within the range of Mayer’s waves (80–120 mHz). Results. The state of cerebral autoregulation was imparied on both sides in 90 % patients with the symptomatic carotid occlusion (0.3 ± 0.3 rad ipsilateral, 0.7 ± 0.6 rad contralateral). The state of cerebral autoregulation was not impaired in 79 % patients with asymptomatic carotid occlusion (1.0 ± 0.3 rad ipsilateral, 1.1 ± 0.4 rad contralateral). The flow velocity index in the contralateral internal carotid artery (306 ± 109 ml / min) and the ipsilateral vertebral (139 ± 69 ml / min) and external carotid (175 ± 72 ml / min) arteries was increased. Conclusions. Noninvasive preoperative assessment of cerebral autoregulation and blood flow distribution in the precerebral arteries makes to evaluate the state of the cerebrovascular reserve to quantify and can be used to determining indications for cerebral revascularization in patients with carotid occlusion.