Related Experiment Video

Updated: Jun 30, 2026

Noninvasive Electrocardiography in the Perinatal Mouse
04:36

Noninvasive Electrocardiography in the Perinatal Mouse

Published on: June 12, 2020

Cardiac repolarization instability during normal postnatal development

Salim F Idriss1, Jamie A Bell

  • 1Pediatric Cardiology, Duke University Medical Center, Durham, NC 27710, USA. salim.idriss@duke.edu

Journal of Electrocardiology
|September 23, 2008
PubMed

Insights

T-wave alternans (TWA), a marker of heart electrical instability, changes with age in rabbits. This study found TWA is highest in young rabbits and decreases as they mature, indicating age-dependent repolarization changes.

Area of Science:

  • Cardiology
  • Developmental Biology
  • Electrophysiology

Background:

  • Long QT syndrome is a cardiac disorder linked to QT interval prolongation and sudden death, particularly in children.
  • Repolarization instability during development can increase susceptibility to fatal arrhythmias.
  • T-wave alternans (TWA) on ECGs indicate electrical instability and correlate with arrhythmia risk in adults.

Purpose of the Study:

  • To investigate age-dependent changes in T-wave alternans (TWA) properties in rabbits.
  • To characterize TWA induction and properties longitudinally in vivo and in vitro.
  • To understand the developmental susceptibility to arrhythmias in the context of TWA.

Main Methods:

  • Longitudinal in vivo assessment of TWA in propofol-sedated New Zealand white rabbits from 2 to 10 weeks of age via transesophageal pacing.
  • In vitro characterization of TWA induction in isolated infant (2 weeks) and adolescent (7 weeks) rabbit hearts subjected to rapid pacing.
  • Pharmacological intervention with isoproterenol to assess its effect on TWA in adolescent rabbits.

Main Results:

  • TWA amplitude was highest at 2 weeks of age and decreased progressively with age in vivo.
  • Isoproterenol administration increased TWA in adolescent rabbits (8 weeks).
  • In vitro studies showed rapid pacing induced significant TWA in both infant and adolescent hearts, but TWA levels stabilized at lower values in infants.

Conclusions:

  • T-wave alternans properties exhibit significant age dependency in rabbits.
  • Rapid pacing can induce substantial TWA in rabbits, highlighting a potential mechanism for arrhythmia development.
  • These findings suggest developmental changes in cardiac repolarization influence susceptibility to electrical instability and arrhythmias.

More Related Videos

Electrocardiogram Recordings in Anesthetized Mice using Lead II04:16

Electrocardiogram Recordings in Anesthetized Mice using Lead II

Published on: June 20, 2020

Related Concept Videos

Cardiac Action Potential01:30

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 Rhythm01:19

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...
Mechanism of Cardiac Arrhythmias01:28

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.
Disturbances in Heart Rhythm01:29

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...
Correlation between ECG and Cardiac Cycle01:25

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...
ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

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...