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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...

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

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.

Conduction System of the Heart

Conduction System of the Heart

The cardiac conduction system produces and transmits electrical impulses that prompt myocardial contraction, ensuring efficient heart function. This intricate system ensures that the heart beats in a coordinated and efficient manner, beginning with the atria and then the ventricles. The conduction system optimizes cardiac output by maintaining this precise sequence, which is crucial for adequate blood circulation.
This system relies on the unique properties of nodal and Purkinje cells:...

Conduction System of the Heart

Conduction System of the Heart

Autorhythmicity is a term that refers to the heart's inherent ability to generate electrical signals and instigate muscle contractions. This self-regulating conduction system within the heart consists of two key components: the pacemaker cells and specialized conducting cells.
The pacemaker cells are located in two primary nodes: the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node pacemaker cells can autonomously depolarize, triggering an action potential that leads to the...

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...

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Related Experiment Video

Updated: Jun 24, 2026

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

Published on: February 17, 2015

Genetics of cardiac repolarization.

Svati H Shah¹, Geoffrey S Pitt

¹Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, NC, USA. svati.shah@duke.edu

Nature Genetics

|April 2, 2009

Summary

Genome-wide association studies identified genetic variants linked to the electrocardiographic QT interval, a key measure of cardiac repolarization. These findings advance our understanding of genetic factors influencing heart rhythm and sudden cardiac death risk.

Area of Science:

Cardiovascular Genetics
Electrophysiology
Genomics

Background:

The electrocardiographic QT interval reflects cardiac repolarization, and its prolongation is linked to arrhythmias and sudden cardiac death.
Understanding the genetic underpinnings of QT interval variation is crucial for identifying individuals at risk.

Discussion:

Two recent genome-wide association studies (GWAS) investigated genetic variations associated with QT interval duration.
These studies utilized population-based cohorts to ensure robust findings.

Key Insights:

GWAS identified significant associations between QT interval variation and specific genetic variants.
These variants are located within ion channel genes and other novel genomic regions.
The findings highlight the complex genetic architecture influencing cardiac repolarization.

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Last Updated: Jun 24, 2026

Generation of Murine Cardiac Pacemaker Cell Aggregates Based on ES-Cell-Programming in Combination with Myh6-Promoter-Selection

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Published on: February 17, 2015

Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples

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Outlook:

Further research can explore the functional impact of identified variants on cardiac ion channels.
These genetic insights may lead to improved risk stratification for sudden cardiac death.
Future studies could integrate genetic data with clinical factors for personalized cardiovascular risk assessment.