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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

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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...
879
Cardiac Action Potential01:30

Cardiac Action Potential

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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
757
Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers01:24

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

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Adrenergic stimulation generally impacts cardiac rate and rhythm. Specifically, stimulation of the β-adrenoceptors triggers an increase in intracellular calcium ion influx and pacemaker currents, which may cause arrhythmias. Catecholamines like adrenaline also demonstrate β2-adrenoceptor-mediated hypokalemia, impacting cardiac action potential and disrupting the normal cardiac rhythm. Class II antiarrhythmic drugs are β-adrenoceptor antagonists or β-blockers, which...
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Disturbances in Heart Rhythm01:28

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...
842
Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers01:22

Antiarrhythmic Drugs: Class I Agents as Sodium Channel Blockers

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Class I antiarrhythmic drugs are used to treat various types of arrhythmias or irregular heart rhythms. These drugs block the sodium (Na+) channels in the cardiac cells, thereby affecting the movement of electrical impulses across the heart. Class I antiarrhythmic drugs are divided into three subgroups: Class IA, Class IB, and Class IC, each with distinct mechanisms of action and effects on the heart.
Class 1A Antiarrhythmic Drugs: These drugs work by moderately blocking sodium channels,...
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Heart Failure Drugs: Inotropic Agents01:26

Heart Failure Drugs: Inotropic Agents

488
Positive inotropic agents are commonly used as the first line of treatment for heart failure. One such agent is digoxin, derived from the genus Digitalis, which has been known for centuries but effectively utilized since 1785. However, these cardiac glycosides can have potentially toxic effects due to their mechanism of action, which involves inhibiting Na+/K+-ATPase and increasing contractility. Digoxin is absorbed orally and distributed in various tissues, including the CNS. It has a long...
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Related Experiment Video

Updated: May 23, 2025

Electrocardiogram Recordings in Anesthetized Mice using Lead II
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Kratom Cardiotoxicity: Reversible Brugada Pattern and QTc Prolongation.

Andrew H F Miller1, Alex J Krotulski2, Sara E Walton2

  • 1Atrium Health's Carolinas Medical Center, Department of Emergency Medicine, Division of Medical Toxicology, Charlotte, North Carolina, USA.

JACC. Case Reports
|March 7, 2025
PubMed
Summary

Kratom use in a patient with attention-deficit/hyperactivity disorder led to a reversible Brugada pattern and QT prolongation. This highlights potential cardiac risks associated with kratom, a herbal substance affecting multiple receptors.

Keywords:
BrugadaQRS prolongationQT prolongationkratommitragynine

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Area of Science:

  • Pharmacology
  • Cardiology
  • Herbal Medicine Research

Background:

  • Kratom (Mitragyna speciosa) contains alkaloids interacting with opioid, adrenergic, and serotonergic receptors.
  • In vitro studies suggest kratom may inhibit myocardial potassium channels.

Observation:

  • A case study of a patient self-treating attention-deficit/hyperactivity disorder (ADHD) with kratom.
  • The patient presented with cardiac abnormalities after kratom consumption.

Findings:

  • The patient developed a reversible Brugada pattern.
  • QT prolongation was observed in the patient's electrocardiogram.
  • These cardiac events were linked to kratom use.

Implications:

  • Kratom may pose risks for cardiac channelopathies, including Brugada pattern and QT prolongation.
  • Healthcare providers should inquire about kratom use in patients with unexplained cardiac events.
  • Further research is needed to elucidate the cardiovascular safety profile of kratom.