Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

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...
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...
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.
Sex-linked Disorders01:43

Sex-linked Disorders

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological deficits, the disorder is considered sex-linked.
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...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Checkpoint inhibitors in microsatellite instability-high metastatic colorectal cancer: treatment strategies, specificities, and care management questions.

ESMO gastrointestinal oncology·2026
Same author

Metastatic colorectal cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up.

Annals of oncology : official journal of the European Society for Medical Oncology·2026
Same author

Challenges of neoadjuvant immunotherapy in mismatch repair-deficient/microsatellite-unstable localized colon cancer patients.

ESMO open·2026
Same author

ESMO adaptation of Lines of Systemic Therapy (EnLiST): a consensus framework for standardising the designation of lines of therapy in solid tumours.

Annals of oncology : official journal of the European Society for Medical Oncology·2026
Same author

Genetic and transcriptomic analyses of early-onset colon cancer (EOCC): a <i>post hoc</i> analysis of 2973 patients from two adjuvant randomized trials.

ESMO gastrointestinal oncology·2026
Same author

Managing adverse events in patients with metastatic colorectal cancer receiving trifluridine/tipiracil in combination with bevacizumab.

ESMO gastrointestinal oncology·2026

Related Experiment Video

Updated: Jul 18, 2026

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation
07:15

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Published on: January 16, 2019

[Acquired long QT syndrome: a dominant problem?].

C Barnay1, J Taieb, R Morice

  • 1Service de cardiologie, centre hospitalier du Pays d'Aix, avenue des Tamaris, Aix-en-Provence, France. cbarnay@ch-aix.fr

Annales De Cardiologie Et D'Angeiologie
|December 29, 2006
PubMed
Summary

QT prolongation, a drug-induced heart rhythm issue, is primarily caused by blocking the potassium current (Ikr). This increases arrhythmia risk, especially Torsades de Pointes, influenced by patient factors and drug metabolism.

More Related Videos

Electrocardiogram Recordings in Anesthetized Mice using Lead II
04:16

Electrocardiogram Recordings in Anesthetized Mice using Lead II

Published on: June 20, 2020

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes
11:33

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes

Published on: March 12, 2013

Related Experiment Videos

Last Updated: Jul 18, 2026

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation
07:15

Determining the Likelihood of Variant Pathogenicity Using Amino Acid-level Signal-to-Noise Analysis of Genetic Variation

Published on: January 16, 2019

Electrocardiogram Recordings in Anesthetized Mice using Lead II
04:16

Electrocardiogram Recordings in Anesthetized Mice using Lead II

Published on: June 20, 2020

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes
11:33

Isolation and Kv Channel Recordings in Murine Atrial and Ventricular Cardiomyocytes

Published on: March 12, 2013

Area of Science:

  • Pharmacology
  • Cardiology
  • Electrophysiology

Context:

  • QT prolongation is a significant pharmacologic adverse effect.
  • It is primarily linked to the blockade of the outward potassium current (Ikr).
  • This blockade leads to repolarization prolongation, potentially causing early afterdepolarizations and re-entrant arrhythmias like Torsades de Pointes.

Purpose:

  • To explain the mechanisms behind QT prolongation and Torsades de Pointes.
  • To highlight the concept of "repolarization reserve" and its variability.
  • To discuss various risk factors and drug-related influences on QT prolongation.

Summary:

  • Drug-induced QT prolongation results from Ikr current blockade, increasing arrhythmia risk.
  • The "repolarization reserve" concept explains individual susceptibility, influenced by pathologic, genetic, and drug metabolism factors (Cytochrome P450).
  • Risk factors include bradycardia, electrolyte disturbances, cardiac/neurologic conditions, and drug interactions; diagnosis is via ECG, treatment involves magnesium and heart rate acceleration.

Impact:

  • Enhances understanding of drug-induced arrhythmias and their management.
  • Informs clinical practice regarding patient risk stratification and drug selection.
  • Contributes to drug safety monitoring and development by identifying potential risks early.