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Related Concept Videos

Electrocardiogram01:29

Electrocardiogram

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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...
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ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

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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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Cardiac Action Potential01:30

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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.
Ionic Basis of Cardiac Action Potentials
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ECG Interpretation of Rhythms01:24

ECG Interpretation of Rhythms

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

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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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Electrocardiogram Fundamentals01:28

Electrocardiogram Fundamentals

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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
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Related Experiment Video

Updated: Apr 29, 2026

Methods for ECG Evaluation of Indicators of Cardiac Risk, and Susceptibility to Aconitine-induced Arrhythmias in Rats Following Status Epilepticus
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Universal ECG changes in pediatric patients undergoing procainamide challenge.

Christopher P Jordan1, Charles I Berul, Jeffrey P Moak

  • 1Division of Cardiology, Children's National Medical Center, Washington, D.C.; Division of Cardiology, Department of Pediatrics, George Washington University School of Medicine, Washington, D.C.

Pacing and Clinical Electrophysiology : PACE
|May 17, 2014
PubMed
Summary

Procainamide challenge in children consistently prolongs PR, QRS, and QTc intervals, aiding Brugada syndrome evaluation. These ECG changes occurred without adverse events, offering valuable insights for pediatric cardiology.

Keywords:
Brugada syndromepediatric arrhythmiapediatric electrophysiologyprocainamide

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Area of Science:

  • Pediatric Cardiology
  • Electrophysiology
  • Pharmacology

Background:

  • Procainamide is an antiarrhythmic drug known to prolong PR, QRS, and QTc intervals in adults.
  • It is used to unmask Brugada syndrome, characterized by specific ECG findings like right bundle branch block and right precordial ST elevation.
  • This study focuses on the pediatric population to evaluate procainamide's impact on ECG intervals.

Purpose of the Study:

  • To quantify the effect of procainamide on electrocardiographic intervals in pediatric patients undergoing challenge tests.
  • To assess the safety and efficacy of procainamide challenge in diagnosing Brugada syndrome in children.
  • To analyze ECG changes regardless of the final Brugada syndrome diagnosis.

Main Methods:

  • Retrospective review of pediatric patients who underwent procainamide challenge between March 2009 and September 2012.
  • Intravenous procainamide administered over 15 minutes.
  • Electrocardiograms (ECGs) analyzed by blinded investigators to measure interval changes.

Main Results:

  • All pediatric patients showed prolongation of PR, QRS, and QTc intervals after procainamide infusion.
  • Mean prolongation observed: PR (+14%), QRS (+13%), QTc (+15%).
  • QTc prolongation exceeding 460 ms occurred in 76% of patients; no sustained arrhythmias or adverse events were reported.

Conclusions:

  • Procainamide challenge reliably induces ECG interval prolongation (PR, QRS, QTc) in children evaluated for Brugada syndrome.
  • A significant increase (≥20%) in these intervals was observed in all patients without adverse effects.
  • The study suggests QTc prolongation is not solely attributable to QRS widening.