Abstract
Objective: Transcranial Doppler is commonly used to calculate cerebral autoregulation, but measurements are typically restricted to a single cerebral artery. In exploring topographic heterogeneity, this study reports the first thorough comparison of autoregulation in all major cerebral vessels.Methods: In forty healthy adults, flow velocity was monitored in the anterior, middle, and posterior cerebral arteries, and synchronized with arterial blood pressure. A transfer function analysis provided characteristics of autoregulation by quantifying the relationship between blood pressure and cerebral blood flow velocity.Results: Phase, which quantifies the time course of autoregulation, was similar in all vessels. Gain, which quantifies the magnitude of hemodynamic regulation, was lower in posterior cerebral artery, indicative of tighter regulation. However, after adjusting for baseline flow differences in each vascular territory, normalized gain was similar in all vessels.Conclusions: Discriminating dynamic cerebral autoregulation between cerebrovascular territories is feasible with a transcranial doppler based approach. In the posterior cerebral artery of healthy volunteers, absolute flow is more tightly regulated, but relative flow regulation is consistent across cerebrovascular territories.Significance: The methodology can be applied to focal disease states such as stroke or posterior reversible encephalopathy syndrome, in which the topographic distribution of autoregulation may be particularly critical.
Highlights
Cerebral autoregulation (CA) describes the ability to maintain stable cerebral blood flow (CBF) despite fluctuations in blood pressure (BP), protecting the brain from hypoperfusion and hyperperfusion [1, 2]
Phase was similar in all cerebral vessels, indicating a consistent timing of the autoregulatory response
While prior comparisons have been made between MCA and PCA in healthy and disease states [14, 15, 24,25,26], this study represents the first comparison across the ACA, MCA and PCA
Summary
Cerebral autoregulation (CA) describes the ability to maintain stable cerebral blood flow (CBF) despite fluctuations in blood pressure (BP), protecting the brain from hypoperfusion and hyperperfusion [1, 2]. CA impairment is associated with cerebral small vessel disease and dementia [6, 7]. Cerebral Autoregulation Across Vascular Territories predicts stroke risk and cognitive decline [8, 9]. A reliable approach to CA quantification is critical to understanding the pathophysiology of multiple disease states, and holds the potential to personalize care. CA is typically assessed in a single cerebral vessel, neglecting potential topographic heterogeneity. Quantifying CA in different territories could improve our understanding of the pathophysiology underlying cerebrovascular disease. In focal diseases, such as stroke or posterior reversible encephalopathy syndrome (PRES), the topographic distribution of CA may be critical
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