Blunt Cardiovascular Response to Active Standing in Patients with Intracranial Atherosclerotic Stenosis
Yufan Cao1, Yuexuan Dai1, Jiaxin Liu2
1Department of Neurology, Chinese Academy of Medical Sciences and Peking Union Medical College Hospital/Peking Union Medical College, Beijing, China.
Insights
Patients with intracranial atherosclerotic stenosis (ICAS) show blunted cerebral blood flow (CBF) responses to standing. This impaired CBF regulation is partly mediated by reduced heart rate variability (HRV), suggesting a heart-brain connection.
Area of Science:
- Neurology
- Cardiology
- Vascular Medicine
Background:
- Intracranial atherosclerotic stenosis (ICAS) affects cerebral blood flow (CBF) dynamics.
- Active standing simulates rapid blood pressure fluctuations, revealing physiological responses.
- Investigating the interplay between CBF and heart rate (HR) in ICAS is crucial.
Purpose of the Study:
- To examine dynamic changes in CBF and HR during active standing in ICAS patients.
- To assess the interconnectivity of CBF and HR responses in relation to stenosis.
- To explore the role of heart rate variability (HRV) in mediating these responses.
Main Methods:
- Cross-sectional analysis within a prospective cohort.
- Transcranial Doppler monitoring of 302 middle cerebral arteries in 182 subjects.
- Comparison of CBF velocity and HR trends during supine to active standing transitions.
Main Results:
- CBF velocity showed a decrease then rebound upon standing; rebound time was prolonged in stenotic arteries.
- Patients with ICAS exhibited lower maximum HR rangeability and a trend towards lower HRV.
- HRV partially mediated the effect of stenosis on prolonged CBF velocity rebound time (12.76% mediation).
Conclusions:
- Cerebral blood flow in stenotic arteries demonstrates a blunted response to blood pressure fluctuations.
- Reduced HRV may contribute to impaired CBF regulation in ICAS.
- Heart rate monitoring may aid in managing ICAS-related cerebral hypoperfusion.
Introduction:
We sought to investigate the dynamic changes in cerebral blood flow (CBF) and heart rate (HR) and their interconnectivity in response to active standing, a physiological model to simulate rapid blood pressure fluctuation, in patients with intracranial atherosclerotic stenosis (ICAS).
Methods:
The study was a cross-sectional analysis within a prospective cohort. Transcranial Doppler monitoring was performed in 302 middle cerebral arteries from 182 subjects. All subjects started in the supine position, followed by rapid standing. The CBF velocity and HR trend curves were recorded and compared between the groups.
Results:
After the subject stood up, the CBF velocity curve showed a rapid decrease followed by a rebound, while the HR curve showed a rapid increase and dropped back to the baseline. The time to peak CBF velocity rebound was prolonged in the stenotic arteries (19.53 ± 3.8 s) compared with the normal arteries (17.09 ± 3.09 s) (p < 0.001). In patients with ICAS, the maximum HR rangeability was lower (18.1 ± 8.1 vs. 21.3 ± 7.1 bpm, p = 0.013) and the HR variability (HRV) had a trend lower (1.20 ± 0.134 vs. 1.24 ± 0.118, p = 0.07) than the normal controls. The mediating effect analysis showed that the HRV acted as a partial mediating factor of the stenosis on the prolongation of the time to peak CBF velocity rebound, and the proportion of the mediating effect was 12.76%.
Conclusions:
The CBF in the intracranial stenotic artery has a blunt response to rapid blood pressure fluctuation, which could be partially mediated by the decrease in HRV, suggesting a new potential heart-brain talk. HR monitoring could be considered in the management of ICAS-related cerebral hypoperfusion.
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