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Dysrhythmias III: Characteristics of Dysrhythmias

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.

Disturbances in Heart Rhythm

Disturbances in Heart Rhythm

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...

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

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...

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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 II: Classification of Tachyarrhythmias

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...

Cardiopulmonary Resuscitation III: AED Use

Cardiopulmonary Resuscitation III: AED Use

Introduction to AEDAn Automated External Defibrillator (AED) is a portable medical device that analyzes the heart's rhythm and, if necessary, delivers an electrical shock to help the heart re-establish an effective rhythm during sudden cardiac arrest (SCA). SCA occurs when the heart suddenly and unexpectedly stops beating, leading to a loss of blood flow to the brain and other vital organs. In such emergencies, time is of the essence, and using an AED, combined with Cardiopulmonary...

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Related Experiment Video

Updated: Jul 3, 2026

A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts

A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts

Published on: February 17, 2023

Aborted sudden death from sustained ventricular fibrillation.

Krishnakumar Nair¹, Karthikeyan Umapathy, Eugene Downar

¹Division of Cardiology, University Health Network, The Toby Hull Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Ontario, Canada.

|July 16, 2008

Summary

Ventricular fibrillation, a sustained heart rhythm, can sometimes self-terminate. This rare event may involve electrical organization, high catecholamines, and hyperkalemia, offering new therapeutic insights.

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Last Updated: Jul 3, 2026

A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts

A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts

Published on: February 17, 2023

A Rat Model of Ventricular Fibrillation and Resuscitation by Conventional Closed-chest Technique

A Rat Model of Ventricular Fibrillation and Resuscitation by Conventional Closed-chest Technique

Published on: April 26, 2015

Standardized Model of Ventricular Fibrillation and Advanced Cardiac Life Support in Swine

Standardized Model of Ventricular Fibrillation and Advanced Cardiac Life Support in Swine

Published on: January 30, 2020

Area of Science:

Cardiology
Electrophysiology
Medical Research

Background:

Ventricular fibrillation (VF) is typically a sustained and fatal cardiac arrhythmia.
Spontaneous termination of VF within 30 seconds is exceedingly rare in human subjects.

Observation:

The temporal evolution of VF in a patient indicated fluctuating electrical activity organization.
This observed variation in electrical organization over time is a key aspect of the case.

Findings:

The study suggests that the interplay between electrical activity organization, elevated catecholamine levels, and hyperkalemia may facilitate the self-termination of ventricular fibrillation.
These factors, particularly their interaction, are hypothesized to be crucial for spontaneous defibrillation.

Implications:

Understanding the mechanisms of spontaneous defibrillation in VF could lead to novel therapeutic strategies.
This research may pave the way for new treatments for this life-threatening arrhythmia.