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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

Electrocardiogram Fundamentals

Electrocardiogram Fundamentals

Introduction
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin...

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias V: Evaluating Dysrhythmias

Dysrhythmias, also known as arrhythmias, are disturbances in the heart's rhythm that range from benign to life-threatening. A thorough evaluation is crucial for appropriate management and involves a comprehensive medical history, physical examination, and various diagnostic tests.Medical HistorySymptoms: Collect detailed information on palpitations, dizziness, syncope, chest pain, and fatigue. Note their onset, frequency, and triggers.Previous Cardiac Issues: Document any history of 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...

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...

Dysrhythmias I: Introduction

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...

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Related Experiment Video

Updated: Apr 21, 2026

In Vivo Surface Electrocardiography for Adult Zebrafish

In Vivo Surface Electrocardiography for Adult Zebrafish

Published on: August 1, 2019

A practical guide to early repolarization.

Arnon Adler¹, Michael H Gollob

¹aDivision of Cardiology, Tel Aviv Medical Center and Tel Aviv University, Tel Aviv, Israel bDivision of Cardiology, Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada.

Current Opinion in Cardiology

|November 13, 2014

Summary

This summary is machine-generated.

Early repolarization, a common ECG finding, is linked to sudden cardiac death. Early Repolarization Syndrome (ERS) is a rare channelopathy requiring intervention, while most asymptomatic cases have a good prognosis.

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Area of Science:

Cardiology
Electrophysiology
Genetics

Background:

Early repolarization (ER) on ECG is increasingly associated with idiopathic ventricular fibrillation and sudden cardiac death.
Interpreting ER risk is challenging due to its high prevalence (3-13%) in the general population.

Purpose of the Study:

To clarify recent definition changes for early repolarization.
To provide a practical approach for managing patients with this ECG pattern.

Main Methods:

Review of recent population studies and genetic research on early repolarization.
Analysis of electrocardiographic characteristics associated with increased risk.

Main Results:

High-risk ER features include high-amplitude J-point elevation, horizontal/descending ST segments, and inferior lead location.
Early Repolarization Syndrome (ERS) is recognized as a channelopathy in patients with cardiac arrest and a pronounced ER pattern.
Genetic studies suggest mutations in ion channels may underlie ERS, though definitive data are pending.

Conclusions:

ERS patients are rare but face a high risk of recurrent cardiac events, with ICD implantation and quinidine as recommended treatments.
Asymptomatic individuals with ER generally have a good prognosis, with limited need for preventive measures.
Management strategies should differentiate between high-risk ERS and common asymptomatic ER.