Title:Correlation between Decreased Parasympathetic Activity and Reduced Cerebrovascular Reactivity in Patients with Lacunar Infarct
Volume: 14
Issue: 1
Author(s): Kannakorn Intharakham, Kesorn Suwanprasert and Sombat Muengtaweepongsa
Affiliation:
Keywords:
Cerebrovascular reactivity, heart rate variability, lacunar infarction.
Abstract: Reduced cerebrovascular reactivity (CVR) was found in patients with recent lacunar infarct.
However, its mechanisms were controversial. The breath holding maneuver as a vasodilatory stimulus is
clinically useful for an estimation of cerebrovasomotor reactivity in well co-operative patients. Patients
with lacunar infarct have no higher cortical dysfunction and remain well co-operation. The breath holding
maneuver is feasible and safe to perform in patients with lacunar infarct. Autonomic nervous system
regulates systemic vascular activity. Regulation of autonomic function to cerebrovascular reactivity has
been reported in the literature. We examined the correlation between autonomic functions with frequency
and nonlinear heart rate variability (HRV) and cerebrovascular reactivity in patients with lacunar infarct
by application of breath holding maneuver. Fifteen patients with lacunar infarct (8 women, age 65.6 ±
13.61) and 16 healthy controls (11 women, age 27.33 ± 3.85) were continuously monitored at baseline
before maneuver (basal phase), during CVR induction (experimental phase) with breath holding
maneuver and after maneuver (recovery phase), for arterial blood pressure (ABP), electrocardiography
(EKG), mean cerebral blood flow velocity (mCBFV) of middle cerebral arteries (MCA) by transcranial
doppler (TCD). The short term-one minute HRV was analyzed from EKG signals for low frequency (LF)/
high frequency (HF) ratio, nonlinear of standard deviation 1 (SD1), standard deviation 2 (SD2), cardiac
Sample Entropy (SampEn) and Shannon Entropy. Significant increasing in mCBFV, LF/HF ratio,
SD2/SD1, Shannon Entropy and inversely decreasing SampEn during breath holding maneuver compared
with baseline were found in both groups (p<0.05). The trend of cerebrovascular reactivity is similar in
both groups. However, there were differences of mCBFV, systolic blood pressure (SysBP) in the whole
phases (basal, experiment and recovery) between patients and controls (p<0.05). Less scattered signals of
SD1 with low value in patient group were illustrated from Poincaré (p<0.05). This indicated less degree
of parasympathetic drive in the patients compared to the controls. Moreover, significant positive
correlation between systolic bloods pressure and mCBFV in patients suggests impact of autonomic
control and cerebral blood flow on the patho-physiological mechanism of vasodilatation, triggered by
hypercapnia from breath holding maneuver in patients with lacunar infarct. Reduction of cerebrovascular
reactivity in patients with lacunar infarct may relate with decreased parasympathetic activity. Further
study is required to demonstrate whether these findings mean mechanisms of lacunar infarct or the effect
of hypertensive response.
