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Related Concept Videos

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...
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
Dysrhythmias II: Classification of Tachyarrhythmias01:28

Dysrhythmias II: Classification of Tachyarrhythmias

Tachyarrhythmias are a type of dysrhythmia where the heart rate exceeds 100 beats per minute. Here are some common types of tachyarrhythmias:Sinus TachycardiaSinus tachycardia originates from increased impulses from the sinus node, leading to an elevated heart rate. It is often triggered by stress, fever, or exercise.Patients may experience palpitations, a sensation of a racing heart, dizziness, and chest discomfort.Causes and Risk Factors: Common causes include physical exertion, emotional...
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...

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Related Experiment Video

Updated: Jul 18, 2026

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations
12:09

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

Published on: January 8, 2013

Variability in repeated pattern ventricular arrhythmia: application of a reentry model.

D Sapoznikov1, M H Luria

  • 1Department of Cardiology, Hadassah University Hospital, Ein Kerem, Jerusalem, Israel.

Journal of Electrocardiology
|July 17, 2001
PubMed
Summary

Repeated pattern ventricular arrhythmia (RPVA) involves sinus beats between ectopic beats. A computer model suggests RPVA order changes are linked to reentry pathway refractory periods, not just heart rate.

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Last Updated: Jul 18, 2026

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations
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Published on: January 8, 2013

Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction
06:57

Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction

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A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts
07:56

A Model of Long-Term Ventricular Fibrillation in Isolated Rat Hearts

Published on: February 17, 2023

Area of Science:

  • Cardiology
  • Computational Biology
  • Medical Imaging

Background:

  • Repeated pattern ventricular arrhythmia (RPVA) is characterized by regular sequences of sinus beats interspersed with ventricular ectopic beats.
  • The 'order' of RPVA is defined by the number of sinus complexes between these ectopic beats.
  • Understanding the mechanisms underlying RPVA is crucial for diagnosing and managing cardiac arrhythmias.

Purpose of the Study:

  • To investigate the relationship between RPVA order and electrophysiological properties using a computer model.
  • To determine if changes in RPVA order are more influenced by refractory periods or heart rate.
  • To explore the potential of electrocardiogram (ECG) measurements for estimating pathway refractory periods.

Main Methods:

  • Development of a computer model simulating cardiac reentry mechanisms to generate RPVA.
  • Analysis of simulated data to derive regions of RPVA orders based on sinus RR intervals, coupling intervals, and pathway refractory periods.
  • Comparison of model predictions with ECG-measured time intervals from patients.

Main Results:

  • The study identified a variable relationship between RR intervals and different RPVA orders in patients.
  • The computer model indicated that changes in RPVA order are more sensitive to variations in the reentry refractory period than to heart rate fluctuations.
  • The model successfully explained the longer RR intervals observed in interpolated beats within certain patient groups.

Conclusions:

  • Refractory periods of both normal and reentry pathways can be estimated from ECG-measured intervals.
  • Changes in the reentry refractory period are a more likely driver of RPVA order variations than heart rate changes.
  • The reentry model provides a valuable framework for understanding the electrophysiological basis of RPVA and interpreting ECG findings.