Related Experiment Video

Updated: Aug 2, 2026

Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples
14:39

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

Published on: April 21, 2014

Concealed ventricular bigeminy with exceptions due to time-dependent modulation of an ectopic rhythm

G Oreto1, G Satullo, F Luzza

  • 1Istituto Pluridisciplinare di Clinica Medica, Universita di Messina, Italy.

Chest
|March 1, 1988
PubMed

Insights

This study details atypical concealed bigeminy, a rare heart rhythm where sinus node slowing causes unusual patterns. The findings explain this phenomenon using modulated parasystole and phase-response curves.

Area of Science:

  • Cardiology
  • Cardiac Electrophysiology

Background:

  • Concealed bigeminy is a recognized arrhythmia pattern.
  • Typically, interectopic intervals in concealed bigeminy contain an odd number of sinus beats.

Observation:

  • A case of atypical concealed bigeminy was observed.
  • Some interectopic intervals contained an even number of sinus beats, deviating from the typical pattern.

Findings:

  • This atypical pattern occurs specifically during sinus node slowing.
  • The phenomenon is explained by modulated parasystole.
  • A phase-response curve effectively models the modulating effect of sinus impulses on the parasystolic focus, accounting for all observed interectopic intervals.

Implications:

  • Provides a deeper understanding of complex cardiac arrhythmias.
  • Offers a mechanistic explanation for atypical concealed bigeminy.
  • Highlights the importance of considering modulated parasystole in interpreting unusual electrophysiological patterns.

More Related Videos

Ablation of Ischemic Ventricular Tachycardia Using a Multipolar Catheter and 3-dimensional Mapping System for High-density Electro-anatomical Reconstruction06:57

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

Published on: January 31, 2019

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System10:17

Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System

Published on: April 11, 2025

Related Concept Videos

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 III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

Dysrhythmias, also known as arrhythmias, are irregular heart rhythms that result from abnormal electrical activity in the heart, affecting its ability to circulate blood efficiently. Tachyarrhythmias, a subset of dysrhythmias, are characterized by abnormally fast heart rates exceeding 100 beats per minute. Here are some types of tachyarrhythmias with their distinct ECG features:Sinus Tachycardia:Sinus tachycardia presents a regular heart rhythm with an increased rate of 101-180 beats per minute.
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

Bradyarrhythmias are cardiac rhythm disorders characterized by a slower-than-normal heart rate, typically defined as fewer than 60 beats per minute. Some of which are discussed here:Sinus BradycardiaSinus bradycardia presents a heart rate lower than 60 beats per minute, with a regular rhythm originating from the SA node. The ECG typically shows normal P waves preceding each QRS complex, a normal PR interval (0.12 to 0.20 seconds), and a normal QRS duration (0.06 to 0.10 seconds).First-Degree AV...
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...