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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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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.
Ionic Basis of Cardiac Action Potentials
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Electrophysiology of Normal Cardiac Rhythm01:19

Electrophysiology of Normal Cardiac Rhythm

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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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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
An ECG utilizes electrodes on the skin...
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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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Cardiopulmonary Resuscitation III: AED Use01:23

Cardiopulmonary Resuscitation III: AED Use

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Introduction to AEDAn Automated External Defibrillator (AED) is a portable medical device that analyzes the heart's rhythm and, if necessary, delivers an electrical shock to help the heart re-establish an effective rhythm during sudden cardiac arrest (SCA). SCA occurs when the heart suddenly and unexpectedly stops beating, leading to a loss of blood flow to the brain and other vital organs. In such emergencies, time is of the essence, and using an AED, combined with Cardiopulmonary...
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Related Experiment Video

Updated: Apr 12, 2026

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

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Electrocardiographic parameters predict super-response in cardiac resynchronization therapy.

Marta Cvijić1, David Žižek1, Bor Antolič1

  • 1University Medical Centre Ljubljana, Department of Cardiology, Ljubljana, Slovenia.

Journal of Electrocardiology
|May 14, 2015
PubMed
Summary

Predicting super-response to cardiac resynchronization therapy (CRT) is crucial. Post-implant QRS duration and relative QRS shortening are key ECG predictors of super-response in CRT patients.

Keywords:
Cardiac resynchronization therapyECGSuper-response

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Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System
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Area of Science:

  • Cardiology
  • Medical Devices
  • Electrophysiology

Background:

  • Cardiac resynchronization therapy (CRT) is a standard treatment for heart failure.
  • Identifying patients likely to achieve optimal outcomes from CRT remains challenging.
  • Predictive markers for CRT super-response are needed.

Purpose of the Study:

  • To evaluate the utility of electrocardiogram (ECG) parameters in predicting super-response to CRT.
  • To identify specific ECG characteristics associated with significant treatment benefits.

Main Methods:

  • 101 heart failure patients undergoing CRT implantation were studied.
  • 12-lead surface ECGs were recorded at baseline and post-implantation.
  • Super-response was defined as a ≥30% decrease in left ventricular end-systolic volume at 12 months.

Main Results:

  • 31.7% of patients were classified as super-responders.
  • Super-responders exhibited shorter post-implant QRS duration (148 ms vs. 162 ms).
  • Greater relative QRS shortening was observed in super-responders (12.1% vs. 1.7%).
  • Post-implant QRS duration and relative QRS shortening independently predicted super-response.

Conclusions:

  • Absolute post-implant QRS duration and relative QRS shortening are significant ECG predictors of CRT super-response.
  • These ECG parameters offer valuable insights into patient outcomes following CRT.
  • Larger prospective studies are recommended to validate these findings.