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Inspiratory and expiratory sinus arrhythmia in healthy human
Pascale Calabrese1, Sophie Lambert-Lacroix1
1Université Grenoble Alpes, CNRS, UMR 5525, Grenoble, France.
Physiological Reports
|April 2, 2025
Summary
This study differentiates between inspiratory and expiratory sinus arrhythmia in healthy subjects. Findings suggest focusing on expiratory phases to observe changes in vagal cardiac activity.
Area of Science:
- Physiology
- Cardiology
- Respiratory System
Background:
- Sinus arrhythmia, the variation in heart rate with respiration, is a well-known phenomenon.
- Understanding the distinct characteristics of inspiratory and expiratory phases on cardiac activity is crucial for accurate physiological assessment.
Purpose of the Study:
- To investigate and compare the relationship between respiratory phases and heart rate variability in healthy individuals.
- To determine if there are significant differences in cardiac responses during inspiration versus expiration.
Main Methods:
- Recorded electrocardiogram (ECG) and breathing in 33 healthy subjects at rest.
- Categorized RR intervals based on respiratory phases (inspiration/expiration) and analyzed their relationship with respiratory durations.
- Calculated correlation coefficients and regression slopes to quantify heart rate changes during different respiratory phases.
Main Results:
- Linear relationships were observed between RR intervals and normalized respiratory durations in most subjects.
- The rate of heart rate change (slope) varied among individuals.
- Absolute slope values for intervals during inspiration (II) were not consistently higher than those during expiration (EE).
Conclusions:
- There are distinct differences between inspiratory and expiratory sinus arrhythmia.
- Expiratory phases may be more sensitive for detecting changes in vagal cardiac activity.
- Future research should consider the differential effects of respiratory phases on cardiac autonomic regulation.
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