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Moderate exercise induces different autonomic modulations of sinus and AV node
Andreas Schuchert1, Stefan M Wagner, Gaby Frost
1Medical Clinic III, University Hospital Hamburg-Eppendorf, Hamburg, Germany. schuchert@uke.uni-hamburg.de
Pacing and Clinical Electrophysiology : PACE
|March 1, 2005
Summary
This study shows that heart rate variability (HRV) intervals (PP and RR) change during exercise, unlike PR intervals. Ventricular HRV appears to originate from sinus node activity, suggesting independent autonomic control of the sinus and AV nodes.
Area of Science:
- Cardiology
- Physiology
- Biomedical Engineering
Background:
- Surface ECGs typically use RR intervals for heart rate variability (HRV) due to P-wave detection difficulties.
- Intracardiac electrograms offer a more precise method for analyzing atrial and ventricular intervals.
Purpose of the Study:
- To assess changes in RR, PP, and PR intervals at rest and during moderate exercise.
- To evaluate heart rate variability (HRV) using intracardiac electrograms.
- To investigate the independence of autonomic inputs to the sinus and AV nodes.
Main Methods:
- Recorded high-resolution atrial and ventricular intracardiac electrograms from 10 pacemaker patients.
- Analyzed 150 heart cycles at rest and during moderate exercise (walking).
- Calculated HRV indices like SDNN and power spectral densities (LF, HF), and the LF/HF ratio.
Main Results:
- SDNN for PP and RR intervals significantly decreased during exercise (P < 0.05).
- The LF/HF ratio increased significantly in both atrium and ventricle during exercise (P < 0.05).
- PR interval HRV parameters (SDNN, total power, LF/HF ratio) showed no significant changes during exercise.
Conclusions:
- Intracardiac electrograms can be reliably used for HRV evaluation during moderate exercise.
- Changes in PP and RR intervals, but not PR intervals, suggest independent autonomic control of sinus and AV nodes.
- Ventricular HRV primarily reflects variations in sinus node pulse formation.