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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

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 of...

Correlation between ECG and Cardiac Cycle

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...

Electrocardiogram

Electrocardiogram

An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...

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 to...

Action Potential: Phases of Stimulation

Action Potential: Phases of Stimulation

The action potential is a complex electrical event that occurs in excitable cells, such as neurons and muscle cells. It consists of several distinct phases, each with specific characteristics.
Resting Phase:
In this phase, the cell's membrane is at its resting potential, typically around -70 millivolts (mV) for neurons. Inside the cell, there is a higher concentration of potassium ions (K+) and a lower concentration of sodium ions (Na+). Voltage-gated sodium channels are closed, and...

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Related Experiment Video

Updated: Jun 6, 2026

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

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Inferolateral early repolarization in athletes.

M Juhani Junttila¹, Solomon J Sager, Monika Freiser

¹Division of Cardiology, Miller School of Medicine, University of Miami, FL, USA. jjunttila@med.miami.edu

Journal of Interventional Cardiac Electrophysiology : an International Journal of Arrhythmias and Pacing

|December 17, 2010

Summary

This summary is machine-generated.

Early repolarization (ER) is common in young athletes, with male gender and left ventricular hypertrophy (LVH) voltage being key associated characteristics. This study investigated ER prevalence and its links to specific athlete demographics and cardiac markers.

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Area of Science:

Cardiology
Sports Medicine
Electrocardiography

Background:

Early repolarization (ER) is typically a benign ECG pattern in young athletes.
However, inferolateral ER has been linked to an increased risk of sudden cardiac death (SCD).

Purpose of the Study:

To determine the prevalence of inferolateral ER in young collegiate athletes.
To identify characteristics associated with this specific ER pattern.

Main Methods:

Analyzed ECGs from 503 collegiate athletes (ages 17-24).
Collected data on gender, weight, race, sport, and family history of SCD.
Defined ER based on J-point or R-wave down-slope criteria in inferior or lateral leads.
Included Sokolow-Lyon voltage and RR interval measurements.

Main Results:

ER was prevalent in 30% of athletes (inferior 20%, lateral 21%, both 11%).
Male gender (59%) and left ventricular hypertrophy (LVH) voltage (39%) were significantly associated with ER.
A trend towards longer RR intervals was observed in the inferior ER group.
Higher prevalence of ER was noted in African-American athletes, though not statistically significant.

Conclusions:

Early repolarization (ER) is a frequent finding in young athletes.
Left ventricular hypertrophy (LVH) on ECG is the primary shared characteristic among athletes with ER.
Male gender and a higher prevalence in African-American athletes are also notable associations.