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Atrial repolarization as observable during the PQ interval.
Zenichi Ihara1, Adriaan van Oosterom, Rudi Hoekema
1Signal Processing Institute, Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland. zenichi.ihara@epfl.ch
Journal of Electrocardiology
|May 3, 2006
Summary
Atrial repolarization significantly influences body surface potentials during the PQ interval, revealing discordant "atrial T waves" in healthy subjects. This suggests minor variations in atrial action potential durations.
Area of Science:
- Cardiology
- Electrophysiology
- Biophysics
Background:
- The PQ interval of the electrocardiogram (ECG) is traditionally associated with atrial depolarization and conduction.
- Understanding atrial repolarization's contribution to body surface potentials is crucial for comprehensive cardiac electrical activity analysis.
Purpose of the Study:
- To investigate the role of atrial repolarization in generating body surface potentials during the PQ interval.
- To analyze low-amplitude signals within the PQ segment using advanced ECG mapping.
Main Methods:
- High-resolution (64-lead) electrocardiograms were recorded from healthy individuals.
- Body surface potential maps and vectorcardiogram XYZ signals were analyzed, focusing on the PQ segment.
- Special attention was given to the low-amplitude signals between the P wave's end and QRS onset.
Main Results:
- Standard P-wave measurements were within normal limits.
- The PQ segment was found to be non-isoelectric, exhibiting potential distributions similar to the P wave but with reversed polarity and lower amplitude.
- Extremes in local potentials were detected at locations not covered by standard ECG leads.
Conclusions:
- Atrial repolarization significantly contributes to body surface potentials during the PQ interval.
- Discordant "atrial T waves" were observed, indicating a small dispersion in atrial action potential durations.
- These findings refine our understanding of atrial electrical activity beyond depolarization.