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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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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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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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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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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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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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Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
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ECG parameters predict left ventricular conduction delay in patients with left ventricular dysfunction.

Gianni Pastore1, Massimiliano Maines2, Lina Marcantoni1

  • 1Department of Cardiology, Rovigo General Hospital, Rovigo, Italy.

Heart Rhythm
|July 18, 2016
PubMed
Summary
This summary is machine-generated.

Estimating left ventricular electrical delay (Q-LV) is crucial for cardiac resynchronization therapy (CRT). Left bundle branch block (LBBB) shows prolonged Q-LV, while right bundle branch block (RBBB) shows short Q-LV, with specific ECG patterns predicting Q-LV in IVCD.

Keywords:
Cardiac resynchronization therapyHeart failureLeft bundle branch blockLeft ventricular electrical delayNonspecific intraventricular conduction delayRight bundle branch block

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Diagnostics

Background:

  • Estimating left ventricular electrical delay (Q-LV) using a 12-lead electrocardiogram (ECG) is vital for assessing the effectiveness of cardiac resynchronization therapy (CRT).
  • Understanding Q-LV variations across different conduction abnormalities is key to optimizing CRT patient selection and outcomes.

Purpose of the Study:

  • To investigate the impact of the Q-LV interval on ECG configuration in patients undergoing CRT.
  • To analyze Q-LV characteristics in patients with left bundle branch block (LBBB), right bundle branch block (RBBB), and intraventricular conduction delay (IVCD).

Main Methods:

  • 192 patients undergoing CRT implantation were classified into LBBB, RBBB, and IVCD groups.
  • The IVCD group was further divided into left (L)-IVCD and right (R)-IVCD subgroups.
  • Q-LV intervals were measured and correlated with ECG parameters like QRS duration and notching.

Main Results:

  • LBBB patients exhibited significantly prolonged Q-LV intervals (147.7 ± 14.6 ms), all exceeding 110 ms.
  • RBBB patients showed very short Q-LV intervals (75.2 ± 16.3 ms), all below 110 ms.
  • In L-IVCD, mid-QRS notching/slurring strongly correlated with longer Q-LV intervals; R-IVCD patients unexpectedly had longer Q-LV intervals (127.0 ± 12.5 ms).

Conclusions:

  • LBBB is associated with markedly prolonged Q-LV intervals, while RBBB indicates short Q-LV intervals.
  • Mid-QRS notching in lateral leads is a strong predictor of longer Q-LV in L-IVCD.
  • R-IVCD represents a distinct subgroup characterized by a prolonged Q-LV interval, relevant for CRT evaluation.