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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...
Exercise Stress Test01:26

Exercise Stress Test

Introduction
Exercise stress testing, commonly known as a treadmill test, is a noninvasive procedure used to evaluate cardiovascular function and diagnose heart conditions.
Definition
An exercise stress test measures the heart's response to exertion using a treadmill or stationary bicycle. Chest electrodes record the heart's electrical activity through an ECG, and blood pressure is monitored regularly.
Purposes
ECG Interpretation of Rhythms01:24

ECG Interpretation of Rhythms

An electrocardiogram (ECG)graphically represents the heart's electrical activity on ECG paper or a monitor.
Components of the Electrocardiogram
The primary components of a normal ECG waveform in Normal sinus rhythm(NSR) include the P wave, PR interval, QRS complex, ST segment, T wave, and occasionally a U wave.
ECG waveforms are divided by vertical and horizontal lines at standard intervals.
The horizontal axis measures time and rate, and the vertical axis measures amplitude or voltage. When...
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...
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
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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Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice
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Marked negative T waves in athletes: ECG normalization after detraining.

T Vessella1, R Cardillo, M Bianco

  • 1Sports Medicine Unit, Catholic University of Sacred Heart, Rome, Italy - massimiliano.bianco@fastwebnet.it.

The Journal of Sports Medicine and Physical Fitness
|August 2, 2013
PubMed
Summary

Ventricular repolarization abnormalities in athletes may indicate underlying heart disease, not just an athlete's heart. These ECG changes can disappear with detraining but may signal future cardiovascular complications.

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Area of Science:

  • Cardiology
  • Sports Medicine
  • Clinical Electrocardiography

Background:

  • Ventricular repolarization abnormalities (VRA) in athletes with normal cardiac structure pose diagnostic challenges.
  • Distinguishing athlete's heart from underlying pathology is crucial for appropriate management.

Observation:

  • A case study of an athlete presenting with significant ECG abnormalities (giant negative T waves, ST depression).
  • Initial echocardiogram showed a small left ventricular cavity and mild hypertrophy.
  • ECG abnormalities resolved after two months of detraining, with minimal changes in echocardiogram findings.

Findings:

  • Despite transient resolution of VRA with detraining, the athlete later developed cardiovascular complications suggestive of Hypertrophic Cardiomyopathy.
  • VRA reappeared during high workloads and recovery in a later stress test ECG.

Implications:

  • Marked VRA in athletes, even if reversible with detraining, should be considered a potential marker of underlying cardiac disease.
  • This case highlights the importance of long-term follow-up for athletes with significant ECG abnormalities.
  • Rethinking the interpretation of VRA in athletes to prioritize the detection of subclinical cardiac conditions.