Highlights
- •Cerebral hemodynamics can be measured in several ways in unilateral high-grade carotid stenosis.
- •Each measure showed significant asymmetry, but there was low correlation among them.
- •Low correlation among hemodynamic measures suggests unique physiological contributions.
- •Choice of hemodynamic measurement techniques depends on the outcome of interest.
Abstract
Background
Cerebral blood flow (CBF) regulation is a critical element in cerebrovascular pathophysiology,
particularly in large vessel disease, but the best method to use for hemodynamic assessment
is not clear. We examined 4 different blood-flow related measures in patients with
unilateral high-grade carotid artery disease, assessing asymmetry between the occluded
vs non-occluded side, and the correlations among the measures.
Methods
Thirty-three patients (age 50–93, 19 M) with unilateral 80–100% ICA occlusion but
no stroke underwent: 1) mean flow velocity (MFV) in both middle cerebral arteries
by transcranial Doppler (TCD), 2) quantitative resting CBF using pseudo-continuous
arterial spin labeling (pCASL) MRI, 3) vasomotor reactivity (VMR) in response to 5%
CO2 inhalation, and 4) dynamic cerebral autoregulation (DCA) assessing the counter-regulation
of blood flow to spontaneous changes in blood pressure using TCD monitoring and finger
photoplethysmography. Paired t-tests and Pearson correlations assessed side-to-side differences within each measure,
and correlations between measures.
Results
CBF (p = 0.001), MFV (p < 0.001), VMR (p = 0.008), and DCA (p = 0.047) all showed significantly lower values on the occluded side. The 4 measures
were independent of each other on correlation analysis, even when controlling for
age and anterior circle of Willis collateral (all partial correlations <0.233 and p-values >0.468).
Conclusions
These 4 measures showed high sensitivity to the occluded carotid artery, but their
dissociation suggests that any given measure only partially characterizes the hemodynamic
state. Additional research is needed to explore the multifaceted biology of cerebral
blood flow regulation.
Keywords
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Article info
Publication history
Published online: May 07, 2016
Accepted:
May 6,
2016
Received in revised form:
May 4,
2016
Received:
December 23,
2015
Identification
Copyright
© 2016 Elsevier B.V. All rights reserved.
