Related Experiment Video
Updated: Jun 26, 2026
Rat Model of Right-Sided Cardiac Remodeling and Arrhythmia Using Pulmonary Artery Banding
Published on: August 30, 2024
Detailed ECG analysis of atrial repolarization in humans
Fredrik Holmqvist1, Jonas Carlson, Pyotr G Platonov
1Department of Cardiology, Lund University Hospital, Lund, Sweden. fredrik.holmqvist@med.lu.se
Insights
The human Ta wave, representing atrial repolarization, is typically opposite in polarity and 2-3 times longer than the P wave. Further analysis requires QRST cancellation algorithms for improved accuracy.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Imaging
Background:
- Human atrial repolarization data, specifically the Ta wave, is limited due to ECG obscuration by the QRS complex.
- The study focused on patients with third-degree AV block to investigate the human Ta wave.
Purpose of the Study:
- To describe the characteristics of the human Ta wave in detail.
- To analyze the duration, polarity, and peak location of the Ta wave.
Main Methods:
- Studied 40 consecutive patients with third-degree AV block.
- Recorded standard 12-lead ECGs, transformed to orthogonal leads, and analyzed using signal-averaged P wave analysis.
- Discontinued all anti-arrhythmic drugs prior to ECG recording.
Main Results:
- The Ta wave exhibited opposite polarity to the P wave in all leads.
- Ta wave duration was generally two to three times the P wave duration (Ta: 323 ± 56 ms).
- No correlation was found between P wave duration and Ta duration, or Ta peak amplitude and Ta duration.
Conclusions:
- The Ta wave's characteristics (opposite polarity, longer duration) were elucidated.
- Analysis of the Ta wave during normal AV conduction is challenging for differentiating normal from abnormal atrial repolarization.
- Development of a QRST cancellation algorithm during sinus rhythm is suggested for enhanced Ta wave analysis.
Introduction:
Data on human atrial repolarization are scarce since the QRS complex normally obscures its ECG trace. In the present study, consecutive patients with third-degree AV block were studied to better describe the human Ta wave.
Methods And Results:
Forty patients (mean age 75 years, 17 men) were included. All anti-arrhythmic drugs were discontinued before ECG recording. Standard 12-lead ECGs were recorded, transformed to orthogonal leads and studied using signal-averaged P wave analysis. The average P wave duration was 124 +/- 16 ms. The PTa duration was 449 +/- 55 ms (corrected PTa 512 +/- 60 ms) and the Ta duration (P wave end to Ta wave end) was 323 +/- 56 ms. The polarity of the Ta wave was opposite to that of the P wave in all leads. The Ta peaks were located at 196 +/- 55 ms in Lead Y, 216 +/- 50 ms in Lead X, and 335 +/- 92 in Lead Z. No correlation was found between P wave duration and Ta duration, or between Ta peak amplitude and Ta duration. The morphology of the Ta wave was similar regardless of the interatrial conduction.
Conclusions:
The Ta wave has the opposite polarity, and the duration is generally two to three times that, of the P wave. Although the Ta peak may occasionally be located in the PQ interval during normal AV conduction, it is unlikely that enough information can be obtained from analysis of this segment to differentiate normal from abnormal atrial repolarization. Hence, an algorithm for QRST cancellation during sinus rhythm is needed to further improve analysis.
Related Concept Videos
01:29Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
01:25Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
01:25ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias
01:28Electrocardiogram Fundamentals
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin to...
01:30Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
01:19Electrophysiology of Normal Cardiac Rhythm