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Related Concept Videos

Cardiac Action Potential01:30

Cardiac Action Potential

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Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
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.
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Electrophysiology of Normal Cardiac Rhythm01:19

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The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase...
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Aortic Regurgitation II: Clinical Features and Diagnostic Tests01:22

Aortic Regurgitation II: Clinical Features and Diagnostic Tests

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Aortic valve regurgitation (AR) occurs when the aortic valve fails to close properly, allowing blood to flow backward from the aorta into the left ventricle. This backflow can result in two distinct clinical presentations: acute and chronic AR, each characterized by its own set of symptoms and physical findings.Acute Aortic RegurgitationAcute AR presents with a sudden onset of severe symptoms. Patients typically experience profound dyspnea (shortness of breath), chest pain, and signs of left...
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ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias

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Arrhythmia is a condition characterized by an irregular heart rhythm, with ECG changes that differ based on its origin and nature. The types of arrhythmias discussed below include atrial, junctional, and ventricular arrhythmias.Atrial ArrhythmiasPremature Atrial Complexes (PACs): PACs are early atrial beats caused by stress, caffeine, alcohol, electrolyte imbalances, hypoxia, hyperthyroidism, or certain medications (e.g., bronchodilators and decongestants). The ECG shows early P waves with an...
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Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

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The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the 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...
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Cardiac Catheterization III: Left Heart Catheterization01:24

Cardiac Catheterization III: Left Heart Catheterization

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Left heart catheterization is an invasive diagnostic procedure used to evaluate the function and structure of the left side of the heart. It is generally performed to diagnose and treat cardiovascular conditions such as valve abnormalities, coronary artery disease, and congenital heart defects.Diagnostic and therapeutic purposesLeft heart catheterization serves various diagnostic and therapeutic purposes, including:Assessing coronary artery bypass grafts.Evaluating coronary artery disease in...
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Updated: Jan 9, 2026

Transthoracic Echocardiography to Assess Post-Resuscitation Left Ventricular Dysfunction After Acute Myocardial Infarction and Cardiac Arrest in Pigs
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Atrial repolarization in patients with left ventricular dysfunction.

Neha Pulath1, Ramanathan Velayutham1, Anish Bhargav1

  • 1Department of Cardiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.

Journal of Electrocardiology
|December 5, 2025
PubMed
Summary
This summary is machine-generated.

Atrial repolarization (Ta wave) dispersion is increased in patients with left ventricular dysfunction. This finding may indicate an elevated risk for atrial arrhythmias in these individuals.

Keywords:
Atrial arrhythmogenesisAtrial repolarisationLeft ventricular dysfunction PTa wave

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Cardiac Imaging

Background:

  • Atrial depolarization (P wave) and repolarization (Ta wave) are key ECG components.
  • Ta wave is often obscured by the QRS complex, but visible in third-degree AV block.
  • Atrial repolarization has not been previously studied in left ventricular dysfunction.

Purpose of the Study:

  • To investigate atrial repolarization characteristics in patients with left ventricular dysfunction.
  • To compare PTa wave parameters between patients with normal and reduced ejection fraction.

Main Methods:

  • Studied patients with third-degree AV block and pacemakers.
  • Divided patients into normal (LVEF ≥55%) and reduced (LVEF ≤40%) ejection fraction groups.
  • Analyzed PTa segment duration, amplitude, axis, and dispersion from ECGs during VVI pacing.

Main Results:

  • No significant differences in PTa wave duration, amplitude, or axis between groups.
  • PTa dispersion was significantly higher in the reduced ejection fraction group (74 ± 21 ms) compared to the normal ejection fraction group (54 ± 14 ms).

Conclusions:

  • Left ventricular dysfunction does not alter PTa wave amplitude, duration, or axis.
  • Increased PTa dispersion in left ventricular dysfunction may serve as a marker for elevated atrial arrhythmia risk.