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Related Concept Videos

Cardiac Action Potential01:30

Cardiac Action Potential

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
Dysrhythmias II: Classification of Tachyarrhythmias01:28

Dysrhythmias II: Classification of Tachyarrhythmias

Tachyarrhythmias are a type of dysrhythmia where the heart rate exceeds 100 beats per minute. Here are some common types of tachyarrhythmias:Sinus TachycardiaSinus tachycardia originates from increased impulses from the sinus node, leading to an elevated heart rate. It is often triggered by stress, fever, or exercise.Patients may experience palpitations, a sensation of a racing heart, dizziness, and chest discomfort.Causes and Risk Factors: Common causes include physical exertion, emotional...
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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...
Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

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 minute.
Dysrhythmias I: Introduction01:15

Dysrhythmias I: Introduction

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

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

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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Related Experiment Video

Updated: May 20, 2026

Dual-Dye Optical Mapping of Hearts from RyR2R2474S Knock-In Mice of Catecholaminergic Polymorphic Ventricular Tachycardia
09:36

Dual-Dye Optical Mapping of Hearts from RyR2R2474S Knock-In Mice of Catecholaminergic Polymorphic Ventricular Tachycardia

Published on: December 22, 2023

Repolarization syndromes.

Atul Bhatia, Jasbir Sra, Masood Akhtar

    Current Problems in Cardiology
    |July 4, 2012
    PubMed
    Summary
    This summary is machine-generated.

    Repolarization syndromes like Brugada and QT syndromes are increasingly recognized causes of sudden cardiac death (SCD). Early identification through ECG and family history is crucial for preventing SCD in at-risk individuals.

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    Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples
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    Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples

    Published on: April 21, 2014

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    Last Updated: May 20, 2026

    Dual-Dye Optical Mapping of Hearts from RyR2R2474S Knock-In Mice of Catecholaminergic Polymorphic Ventricular Tachycardia
    09:36

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    Published on: December 22, 2023

    Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples
    14:39

    Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples

    Published on: April 21, 2014

    Area of Science:

    • Cardiology
    • Electrophysiology
    • Genetics

    Background:

    • Repolarization syndromes (early repolarization, Brugada, short/long QT) are linked to sudden cardiac death (SCD).
    • Idiopathic ventricular fibrillation is often reclassified as a known repolarization syndrome.
    • Causes are diverse, including genetic mutations, but not all cases are explained.

    Purpose of the Study:

    • To highlight the significance of repolarization syndromes as causes of SCD.
    • To emphasize the importance of early detection and risk stratification.
    • To discuss current therapeutic strategies for preventing arrhythmic death.

    Main Methods:

    • Review of existing literature on repolarization syndromes and SCD.
    • Analysis of diagnostic approaches including 12-lead electrocardiography (ECG).
    • Discussion of underlying electrophysiological mechanisms.

    Main Results:

    • Repolarization syndromes are significant contributors to SCD, often without mechanical abnormalities.
    • High-risk individuals can be identified, but many at-risk individuals remain undiagnosed.
    • Mechanisms include phase 2 reentry, early afterdepolarizations, and vortex reentry.

    Conclusions:

    • Awareness, family history, and ECG are key for SCD prevention in these syndromes.
    • While some long QT syndromes respond to beta-blockers, implantable cardioverter-defibrillators are definitive for high-risk patients.
    • Further research is needed to identify and manage the broader at-risk population.