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Heart rate dynamics during accentuated sympathovagal interaction
M P Tulppo1, T H Mäkikallio, T Seppänen
1Department of Medicine, University of Oulu, Finland.
The American Journal of Physiology
|April 8, 1998
Summary
During heightened sympathovagal interaction, heart rate (HR) dynamics become unstable, exhibiting chaotic behavior. Dynamic analysis of R-R intervals better reveals these complex HR changes than traditional methods.
Area of Science:
- Physiology
- Cardiovascular System
- Autonomic Nervous System
Background:
- Sympathetic and vagal nerve activity often occur together.
- Limited data exists on heart rate (HR) behavior during strong sympathovagal interactions.
Purpose of the Study:
- To investigate heart rate (HR) dynamics during accentuated sympathovagal antagonism.
- To compare dynamic analysis with traditional HR variability techniques.
Main Methods:
- Beat-to-beat HR and blood pressure were recorded in 18 healthy males receiving norepinephrine infusions.
- Spectral analysis and 2D Poincaré plots of HR and R-R intervals were generated.
- Dynamic analysis of beat-to-beat R-R intervals was performed.
Main Results:
- Norepinephrine increased blood pressure and decreased HR, indicating sympathovagal interaction.
- Abrupt, aperiodic R-R interval changes occurred, creating complex Poincaré plots.
- Some subjects showed fixed R-R intervals and loss of respiratory HR modulation, resembling chaotic dynamics.
Conclusions:
- Heart rate behavior becomes unstable and chaotic during accentuated sympathovagal interaction.
- Dynamic analysis of R-R intervals is superior to traditional HR variability methods for identifying these complex dynamics.