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Cyclical modulation of human ventricular repolarization by respiration.
Ben Hanson1, Jaswinder Gill, David Western
1Department of Mechanical Engineering, University College London London, UK.
Frontiers in Physiology
|October 12, 2012
Summary
Respiration cyclically modulates ventricular repolarization, measured by activation-recovery intervals (ARI), shortening with inspiration and lengthening with expiration in healthy individuals.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Function
- Cardiac Electrophysiology
Background:
- Respiratory sinus arrhythmia (RSA) demonstrates heart rate modulation by breathing.
- The study investigated if respiration also cyclically modulates ventricular repolarization.
Purpose of the Study:
- To determine if the respiratory cycle influences ventricular repolarization.
- To assess the measurability of this modulation using endocardial recordings.
Main Methods:
- 16 subjects with healthy ventricles underwent electrophysiological procedures.
- Unipolar electrograms recorded from 20 endocardial sites (10 right, 10 left ventricular).
- Voluntary breathing at 5 frequencies (6-30 breaths/min) with heart rate clamped via pacing.
Main Results:
- Activation-recovery intervals (ARI), a surrogate for action potential duration (APD), showed significant cyclical variation with respiration (p < 0.025).
- ARI shortened during inspiration and lengthened during expiration in all subjects.
- Arterial blood pressure also oscillated with respiration (p < 0.025).
Conclusions:
- Ventricular repolarization (ARI/APD) exhibits cyclical variation with respiration in humans with healthy ventricles.
- This modulation is measurable using multi-site endocardial recordings.
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