Background and Purpose : Cerebrovascular reactivity (CVR) can be estimated by measuring the change of cerebral blood flow that occurs during vasostimulation. To estimate the cerebrovascular reactivity, we investigated the change of flow velocity
of
the
internal carotid artery(ICA) and the middle cerebral artery(MCA) during hyperventilation and hypoventilation with the transcranial doppler. So we studied whether the CVR measured by this method could show a significant difference between the
normal
and
the atherosclerotic subjects and whether the CVR may decrease with age in normal subjects. Methods : Using transcranial doppler, we measured the mean velocity (Vm), the pulsatility index (P.I.) at the resting state, the end of breath-holding and
the end
of hyperventilation in 30 normal and 10 atherosclerotic subjects, so we calculated the percentile change of mean velocity (% ΔVm) and P.I.(%ΔP.I.) after the vasostimulation. We estimated the change of Vm, P.I., %ΔVm and 5ΔP.I. by the age
group
and
compared those parameters between the age-matched normal control and atherosclerotic subjects.
Results: The V in ICA and M1 significantly decreased with age (p<0.01), but there was no significant difference in Vm and P.I. between normal and atherosclerotic subjects. The %ΔVm and %ΔP.I. in response to hyperve4ntilation significantly
decreased
with age in ICA, M1, M2 and there was significant difference in %ΔVm of ICA and m1 after breath-holding and %ΔVm of ICA after hyperventilation between the normal and atherosclerotic subjects.
Conclusion : The breath-holding and hyperventilation tests could be non-invasive and useful methods in estimation of the cerebrovascular reactivity and could be applied in the basal and follow-up evaluation of the cerebrovascular reserve of the
ischemic
stroke patients.
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