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Related Concept Videos

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers01:12

Antiarrhythmic Drugs: Class III Agents as Potassium Channel Blockers

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 the heart's...
Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

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.
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 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...
Disturbances in Heart Rhythm01:29

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...
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...

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Related Experiment Video

Updated: May 26, 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

Amiodarone-induced T-U fusion.

Hesham R Omar1

  • 1Internal Medicine Department, Mercy Hospital and Medical Center, 2525 South Michigan Ave Chicago, IL, USA. hesham_omar2003@yahoo.com

The American Journal of Emergency Medicine
|December 30, 2011
PubMed
Summary

Amiodarone, an antiarrhythmic drug, can cause QT prolongation and T-U fusion, increasing torsade de pointes risk. Correct QT interval calculation is crucial for patient safety.

Area of Science:

  • Cardiology
  • Clinical Electrophysiology
  • Pharmacology

Background:

  • Amiodarone is a key antiarrhythmic medication used for atrial and ventricular arrhythmias.
  • QT interval prolongation is a known adverse effect of amiodarone, linked to increased risk of torsade de pointes.
  • Prominent U waves are also associated with amiodarone use.

Observation:

  • This case highlights amiodarone-induced T-U wave fusion.
  • The patient presented with significant QT prolongation.
  • Other potential causes of QT prolongation, such as electrolyte imbalances and concurrent QT-prolonging medications, were ruled out.

Findings:

  • Amiodarone can lead to T-U wave fusion, a specific electrocardiographic finding.
  • The drug was identified as the cause of QT prolongation in this case.

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Published on: January 31, 2019

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Electrophysiological Assessment of Murine Atria with High-Resolution Optical Mapping
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Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction
06:57

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

Published on: January 31, 2019

  • Exclusion of other factors confirmed amiodarone's role.

    • Implications:

    • Understanding amiodarone-induced T-U fusion is vital for accurate electrocardiogram interpretation.
    • Correct calculation of the QT interval in the presence of T-U fusion is essential for risk assessment.
    • Clinical awareness can prevent misdiagnosis and guide appropriate patient management.