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Related Concept Videos

Electrocardiogram01:29

Electrocardiogram

An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
Cardiac Action Potential01:30

Cardiac Action Potential

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.
Ionic Basis of Cardiac Action Potentials
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

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

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...
Disturbances in Heart Rhythm01:29

Disturbances in Heart Rhythm

Arrhythmia or dysrhythmia refers to an abnormal heart rhythm caused by a defect in the heart's conduction system. It can cause the heart to beat irregularly, too quickly, or too slowly, leading to symptoms like chest pain, shortness of breath, and fainting. Factors such as stress, caffeine, alcohol, nicotine, cocaine, certain drugs, congenital defects, diseases, and electrolyte abnormalities can trigger arrhythmias.
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
Electrocardiogram Fundamentals01:28

Electrocardiogram Fundamentals

Introduction
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...
Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

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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Related Experiment Video

Updated: Jul 8, 2026

Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography
09:23

Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography

Published on: November 24, 2016

Outcomes in athletes with marked ECG repolarization abnormalities.

Antonio Pelliccia1, Fernando M Di Paolo, Filippo M Quattrini

  • 1Institute of Sports Medicine and Science, Italian National Olympic Committee, Rome, Italy. ant.pelliccia@libero.it

The New England Journal of Medicine
|January 11, 2008
PubMed
Summary

Markedly abnormal electrocardiograms (ECGs) in athletes may signal underlying cardiomyopathies, potentially leading to adverse outcomes years later. Continued clinical surveillance is recommended for athletes with these specific ECG patterns.

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Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice
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Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

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Last Updated: Jul 8, 2026

Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography
09:23

Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography

Published on: November 24, 2016

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice
04:45

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

Published on: May 5, 2022

Area of Science:

  • Cardiology
  • Sports Medicine
  • Clinical Electrophysiology

Background:

  • Young, trained athletes can exhibit abnormal 12-lead electrocardiograms (ECGs) without apparent structural heart disease.
  • The long-term clinical significance of these abnormal ECG patterns in athletes remains uncertain.
  • This study investigates the long-term outcomes of athletes presenting with marked repolarization abnormalities on their ECGs.

Purpose of the Study:

  • To assess the long-term clinical outcomes in young, trained athletes with markedly abnormal electrocardiograms (ECGs).
  • To determine if specific ECG abnormalities represent early signs of underlying cardiac disease in athletes.
  • To evaluate the association between abnormal ECG findings and the development of cardiomyopathies in athletes.

Main Methods:

  • Identified 81 athletes with deeply inverted T waves (> or = 2 mm) from a database of 12,550 trained athletes.
  • These athletes had no apparent cardiac disease and underwent serial clinical, ECG, and echocardiographic evaluations for a mean of 9+/-7 years.
  • Compared outcomes with 229 matched control athletes who had normal ECGs.

Main Results:

  • Six percent (5 of 81) of athletes with abnormal ECGs were diagnosed with cardiomyopathies, including arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy, and dilated cardiomyopathy.
  • One athlete with arrhythmogenic right ventricular cardiomyopathy died suddenly at age 24.
  • None of the 229 control athletes with normal ECGs developed cardiomyopathy or experienced cardiac events during follow-up (P=0.001).

Conclusions:

  • Markedly abnormal ECGs in young, healthy-appearing athletes can be the initial manifestation of underlying cardiomyopathies.
  • These cardiomyopathies may not become clinically evident for many years and can lead to adverse clinical outcomes.
  • Athletes with such ECG patterns require ongoing clinical surveillance to monitor for potential cardiac disease development.