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Related Concept Videos

Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

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Arrhythmias are irregular heart rhythms occurring when the heart's electrical impulses become abnormal. These disturbances can lead to various symptoms, depending on their severity and the underlying cause. Some common factors contributing to arrhythmias include hypoxia, ischemia, electrolyte imbalances, excessive catecholamine exposure, drug toxicity, and muscle overstretching. Arrhythmias can be classified into two main types based on the rate and site of origin of abnormal heart rhythms.
908
Disturbances in Heart Rhythm01:28

Disturbances in Heart Rhythm

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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...
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Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers01:22

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

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Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
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Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers01:12

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

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Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of...
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ECG Interpretation of Arrhythmias I: Sinus Arrhythmias01:16

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

203
Arrhythmias are disturbances in the heart's rhythm that lead to abnormal heartbeats. These irregularities can originate from different parts of the heart and are classified based on their origin and nature.
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism,...
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Structure of Lipids03:38

Structure of Lipids

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Lipids include a diverse group of compounds that are largely nonpolar in nature. This is because they are hydrocarbons that include mostly nonpolar carbon-carbon or carbon-hydrogen bonds. Non-polar molecules are hydrophobic (“water fearing”), or insoluble in water. Lipids perform many different functions in a cell. Cells store energy for long-term use in the form of fats. Lipids also provide insulation from the environment for plants and animals. For example, they help keep aquatic...
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Updated: Jun 17, 2025

Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice
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Omega-3 Fatty Acids and Arrhythmias.

Mason D Marcus1, Mark S Link1

  • 1Department of Medicine, Division of Cardiology, UT Southwestern Medical Center, Dallas, TX.

Circulation
|August 5, 2024
PubMed
Summary
This summary is machine-generated.

Omega-3 fatty acids (n-3 PUFAs) show mixed results for heart rhythm. While some studies suggest benefits, high doses may increase atrial fibrillation (AF) risk, with mechanisms still unclear.

Keywords:
atrial fibrillationdocosahexaenoic acideicosapentaenoic acidfatty acids, omega-3

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Area of Science:

  • Cardiology
  • Pharmacology
  • Biochemistry

Background:

  • Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been investigated for both pro- and antiarrhythmic effects.
  • Early studies suggested n-3 PUFAs could prevent sudden cardiac death and atrial fibrillation (AF).
  • However, recent large randomized trials have yielded conflicting results regarding their antiarrhythmic benefits.

Purpose of the Study:

  • To evaluate the complex and often contradictory effects of n-3 PUFAs on cardiac arrhythmias, particularly AF.
  • To assess the current clinical evidence regarding the efficacy and safety of n-3 PUFA supplementation for cardiovascular prevention and AF management.
  • To investigate the potential proarrhythmic effects of specific n-3 PUFA formulations and doses.

Main Methods:

  • Review of preclinical studies and human clinical trials, including randomized controlled trials (RCTs).
  • Analysis of data from large contemporary RCTs investigating moderate and high doses of n-3 PUFAs (including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) for cardiovascular prevention.
  • Examination of findings related to incident AF in participants receiving n-3 PUFA compared to control groups.

Main Results:

  • Accumulated evidence does not support n-3 PUFA supplementation for postoperative AF or secondary AF prevention.
  • Several large RCTs demonstrated a small, significant, dose-dependent increase in incident AF with high-dose n-3 PUFA (icosapent ethyl or EPA+DHA) compared to placebo.
  • These proarrhythmic findings were observed with both monotherapy and mixed formulations, but the underlying mechanisms remain unknown.

Conclusions:

  • The clinical utility of n-3 PUFAs for preventing cardiac arrhythmias, especially AF, is uncertain and potentially controversial.
  • High-dose n-3 PUFA supplementation, including specific formulations like icosapent ethyl, may increase the risk of developing AF.
  • Further research is needed to elucidate the complex pro- and antiarrhythmic mechanisms of EPA, DHA, and their metabolites, and to identify patient subgroups at higher risk.