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Circadian rhythm of heart rate variability is reversibly abolished in ischemic stroke
J T Korpelainen1, K A Sotaniemi, H V Huikuri
1Department of Neurology, University of Oulu, Finland.
Insights
Acute stroke abolishes circadian heart rate variability (HRV). This HRV circadian rhythm returns within 6 months, suggesting a reversible effect. Loss of nocturnal vagal dominance may increase cardiac risks post-stroke.
Area of Science:
- Cardiology
- Neurology
- Autonomic Nervous System Research
Background:
- Acute brain infarction is known to disrupt cardiovascular autonomic function, significantly reducing heart rate variability (HRV).
- Limited data exists on the impact of stroke on the circadian rhythms of heart rate and HRV.
Purpose of the Study:
- To investigate the 24-hour circadian rhythm of heart rate and HRV in patients with acute brain infarction.
- To compare these rhythms in the acute phase and 6 months post-infarction with healthy controls.
Main Methods:
- Prospective analysis of 24-hour ECG data in patients with hemispheric or brainstem infarction and healthy controls.
- Evaluation of time and frequency domain measures of HRV during acute phase and at 6-month follow-up.
Main Results:
- In the acute stroke phase, circadian oscillations of HRV were abolished, with similar values during day and night.
- At 6 months post-infarction, HRV circadian rhythm returned, mirroring patterns in control subjects, with higher nocturnal values.
- No significant difference in HRV patterns was observed between hemispheric and brainstem infarction patients.
Conclusions:
- Circadian fluctuation of HRV is reversibly lost in the acute phase of ischemic stroke.
- The return of circadian HRV rhythm within 6 months indicates a recovery process.
- The temporary loss of nocturnal vagal dominance post-stroke may elevate the risk of cardiac arrhythmias and complications.
Background And Purpose:
Acute brain infarction significantly decreases heart rate variability as a result of cardiovascular autonomic dysregulation. However, information regarding circadian rhythms of heart rate and heart rate variability is limited.
Methods:
In this prospective study, we analyzed 24-hour circadian rhythm of heart rate and the time and frequency domain measures of heart rate variability in 24 patients with hemispheric brain infarction, 8 patients with medullary brainstem infarction, and 32 age- and sex-matched healthy control subjects. ECG data were obtained from the patients in the acute phase and at 6 months after the infarction.
Results:
In the acute phase of stroke, all the components of heart rate variability, ie, standard deviation of RR intervals, total power, high-frequency power, low-frequency power, and very-low-frequency power, were similar at night (from midnight to 6 AM) and during the day (from 9 AM to 9 PM), indicating that the circadian oscillation of heart rate variability had been abolished. At 6 months after brain infarction, the circadian rhythm had returned and, as in the control subjects, the values at night were significantly higher than those in the daytime. The values in hemispheric and in brainstem infarction did not differ significantly from each other.
Conclusions:
These results suggest that circadian fluctuation of heart rate variability is reversibly abolished in the acute phase of ischemic stroke and that it returns during the subsequent 6 months. The loss of the relative vagal nocturnal dominance may contribute to the incidence of cardiac arrhythmias and other cardiovascular complications after acute stroke.