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Related Concept Videos

Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
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Disturbances in Heart Rhythm01:29

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

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

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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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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

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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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Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

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Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per...
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Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
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Is left bundle branch block pattern on the ECG caused by variable ventricular activation sequence?

Lucie Riedlbauchová1, Theodor Adla2, Vojtěch Suchánek1

  • 1Department of Cardiology, Motol University Hospital and 2nd Faculty of Medicine, Charles University, Prague, Czech Republic.

Pacing and Clinical Electrophysiology : PACE
|April 10, 2020
PubMed
Summary
This summary is machine-generated.

Ventricular dyssynchrony assessment using ECG patterns can vary. This study shows consistent ventricular activation sequences in left bundle branch block (LBBB) and LBBB-like patterns, aiding cardiac resynchronization therapy (CRT) response prediction.

Keywords:
ECGbiventricular pacingelectroanatomical mappingleft bundle branch blockresynchronization therapy

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Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction
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Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Imaging

Background:

  • Ventricular dyssynchrony is assessed via QRS complex morphology and width.
  • Similar electrocardiography (ECG) patterns can arise from varied ventricular activation sequences.
  • This variability may explain differing responses to cardiac resynchronization therapy (CRT).

Purpose of the Study:

  • To investigate ventricular activation sequences in patients with left bundle branch block (LBBB).
  • To correlate activation patterns with cardiac resynchronization therapy (CRT) response.
  • To analyze the impact of etiology and myocardial scarring on activation patterns.

Main Methods:

  • Electroanatomical mapping and MRI scans were performed in 11 patients with LBBB.
  • Ventricular activation sequences were studied during LBBB and after CRT programming.
  • Myocardial scarring was analyzed using a 17-segment left-ventricular (LV) model.

Main Results:

  • A consistent right-to-left activation sequence was observed in LBBB, with basal lateral wall showing late activation.
  • This pattern persisted in both true LBBB and LBBB-like presentations, irrespective of etiology (ischemic CAD or non-ischemic DCM).
  • Reverse remodeling was observed in 10 out of 11 patients post-CRT.

Conclusions:

  • Typical LBBB and LBBB-like patterns share consistent activation sequences, independent of etiology or scar location.
  • Right ventricular (RV) apex activation initiation, not LV sequence, may predict left axis deviation.
  • CRT effectively achieved inter- and intraventricular LV resynchronization with minimal changes to RV activation.