Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Mechanism of Cardiac Arrhythmias

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.

Electrophysiology of Normal Cardiac Rhythm

Electrophysiology of Normal Cardiac Rhythm

The normal cardiac rhythm is a synchronized electrical activity that facilitates the regular and coordinated contraction of the heart muscle. This process is essential for efficient blood circulation throughout the body. The fundamental elements involved in establishing and maintaining this rhythm include the unique electrical properties of cardiac muscle cells, the sinoatrial (SA) node's pacemaker function, the specialized conducting system, and the ionic mechanisms underlying each phase...

Cardiac Action Potential

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

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

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...

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...

You might also read

Related Articles

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

Sort by

Same author

Epinephrine Challenge Test: For Whom?

JACC. Clinical electrophysiology·2026

Same author

First-in-human experience after integration of 4D ICE with intracardiac mapping system enabling magnetic navigation and image presentation during catheter ablation of cardiac arrhythmias.

Journal of interventional cardiac electrophysiology : an international journal of arrhythmias and pacing·2026

Same author

Intracardiac echocardiography from the left heart chambers to guide electrophysiology procedures.

Heart rhythm·2026

Same author

Pulsed field ablation for the interventional treatment of atrial fibrillation: a scientific statement of the European Heart Rhythm Association of the European Society of Cardiology, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, the Latin American Heart Rhythm Society, and the Canadian Heart Rhythm Society.

Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology·2026

Same author

Risk stratification in short QT syndrome: Findings from a pooled analysis.

Heart rhythm·2026

Same author

Sex Differences in Long-Term Outcomes of Left Atrial Appendage Closure-Analysis from the LEADER Registry.

Journal of clinical medicine·2026

Search research articles

Related Experiment Video

Updated: Aug 26, 2025

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

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

Published on: December 22, 2023

Arrhythmogenic Effects of Cardiac Memory.

Sami Viskin¹, Ehud Chorin¹, Arie Lorin Schwartz¹

¹Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Israel (S.V., E.C., A.L.S., R.R.).

|October 10, 2022

Summary

Cardiac memory, an electrocardiographic phenomenon, can increase the risk of dangerous heart arrhythmias in susceptible individuals. This review highlights its potential arrhythmogenic effects, previously unappreciated.

Keywords:

atrioventricular block long QT syndrome torsades de pointes

More Related Videos

Laser-Induced Action Potential-Like Measurements of Cardiomyocytes on Microelectrode Arrays for Increased Predictivity of Safety Pharmacology

Laser-Induced Action Potential-Like Measurements of Cardiomyocytes on Microelectrode Arrays for Increased Predictivity of Safety Pharmacology

Published on: September 13, 2022

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Published on: July 3, 2013

Related Experiment Videos

Last Updated: Aug 26, 2025

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

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

Published on: December 22, 2023

Laser-Induced Action Potential-Like Measurements of Cardiomyocytes on Microelectrode Arrays for Increased Predictivity of Safety Pharmacology

Laser-Induced Action Potential-Like Measurements of Cardiomyocytes on Microelectrode Arrays for Increased Predictivity of Safety Pharmacology

Published on: September 13, 2022

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Published on: July 3, 2013

Area of Science:

Cardiology
Electrophysiology

Background:

Cardiac memory describes a transient electrocardiographic phenomenon where T waves normalize gradually after QRS complex morphology returns to baseline.
This phenomenon is often considered an innocent finding.
However, it involves alterations in cardiac repolarization.

Purpose of the Study:

To review the underappreciated arrhythmogenic potential of cardiac memory.
To highlight the link between cardiac memory and the development of ventricular arrhythmias in specific patient populations.

Main Methods:

Review of existing literature on cardiac memory and its electrophysiological underpinnings.
Analysis of the impact of altered repolarization during cardiac memory on cardiac electrophysiology.

Main Results:

Cardiac memory is associated with reduced repolarizing potassium currents, leading to increased left ventricular repolarization gradients.
In patients with pre-existing prolonged QT interval, cardiac memory can precipitate dangerous ventricular arrhythmias, including torsades de pointes.
These arrhythmogenic effects are not widely recognized.

Conclusions:

Cardiac memory is not merely an innocent electrocardiographic curiosity.
It poses a significant risk for triggering ventricular arrhythmias in patients with prolonged QT intervals.
Further clinical awareness and investigation are warranted.