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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.
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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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Disturbances in Heart Rhythm01:29

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 heart...
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ECG Interpretation of Arrhythmias I: Sinus Arrhythmias01:16

ECG Interpretation of Arrhythmias I: Sinus Arrhythmias

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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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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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Dysrhythmias I: Introduction01:15

Dysrhythmias I: Introduction

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Dysrhythmias refers to abnormalities in the heart's rhythm. They result from disruptions in the heart's electrical conduction system, which includes the sinoatrial(SA)node, atrioventricular(AV) node, the bundle of His, bundle branches, and Purkinje fibers.Definition and PathophysiologyDysrhythmias result from disorders of impulse formation, impulse conduction, or both. The heart contains specialized cells in the sinoatrial node, atrioventricular node, and the bundle of His and Purkinje fibers...
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Related Experiment Video

Updated: Nov 5, 2025

Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping
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Regional differences in arrhythmogenesis.

Ben Short

    The Journal of General Physiology
    |May 20, 2021
    PubMed
    Summary

    The subendocardium, the heart's inner layer, is prone to spontaneous calcium release events that trigger arrhythmias. Local calcium calmodulin kinase II (CaMKII) inhibition may reduce these events, offering a potential therapeutic strategy.

    Area of Science:

    • Cardiology
    • Molecular Biology
    • Electrophysiology

    Background:

    • Spontaneous calcium (Ca2+) release events in cardiomyocytes are a primary trigger for cardiac arrhythmias.
    • The subendocardium exhibits unique electrophysiological properties that may predispose it to abnormal Ca2+ handling.

    Discussion:

    • This study investigated the susceptibility of the subendocardium to spontaneous Ca2+ release events.
    • The role of calcium calmodulin kinase II (CaMKII) in mediating these arrhythmogenic events was examined.
    • Local inhibition of CaMKII was explored as a potential therapeutic intervention.

    Key Insights:

    • The subendocardium demonstrates a higher propensity for spontaneous Ca2+ release compared to other cardiac regions.
    • CaMKII activity is implicated in facilitating these aberrant Ca2+ release events in the subendocardium.

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  • Targeting CaMKII locally presents a promising approach to mitigate arrhythmia initiation.

    • Outlook:

    • Further research is warranted to elucidate the precise mechanisms underlying subendocardial Ca2+ handling.
    • Clinical translation of CaMKII inhibitors for arrhythmia management requires rigorous investigation.
    • Exploring regional differences in ion channel function and signaling pathways is crucial for developing targeted therapies.