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Related Concept Videos

Conduction System of the Heart01:20

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 Heart01:19

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...
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...
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...
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...
The Cardiac Cycle01:13

The Cardiac Cycle

The heart beats rhythmically in a sequence called the cardiac cycle—a rapid coordination of contraction (systole) and relaxation (diastole).
The Process
Electrical signals—sent from the sinoatrial (SA) node in the right atrial wall to the atrioventricular (AV) node between the right atrium and right ventricle—cause both atria to simultaneously contract. When the signal reaches the AV node, it pauses for approximately a tenth of a second, allowing the atria to contract and empty blood into the...

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Related Experiment Video

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High-Resolution Endocardial and Epicardial Optical Mapping in a Sheep Model of Stretch-Induced Atrial Fibrillation
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Direction-dependent conduction in lone atrial fibrillation.

Christopher X Wong1, Martin K Stiles, Bobby John

  • 1Cardiovascular Research Centre, Department of Cardiology, Royal Adelaide Hospital and Discipline of Medicine, University of Adelaide, Adelaide, Australia.

Heart Rhythm
|July 20, 2010
PubMed
Summary

Direction-dependent conduction abnormalities are amplified in patients with lone atrial fibrillation (AF). These findings in lone AF patients highlight the interplay between substrate and wavefront direction, impacting arrhythmogenicity.

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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
12:45

Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing

Published on: December 11, 2017

Area of Science:

  • Cardiology
  • Electrophysiology
  • Atrial Fibrillation Research

Background:

  • Patients with lone atrial fibrillation (AF) exhibit an abnormal atrial substrate.
  • Understanding substrate abnormalities is crucial for managing AF.

Purpose of the Study:

  • To investigate the role of direction-dependent conduction in lone atrial fibrillation (AF).
  • To characterize how varying wavefront directions influence electrophysiological properties in lone AF patients.

Main Methods:

  • Studied 24 paroxysmal lone AF patients and 24 reference patients with accessory pathways.
  • Utilized multipolar catheters for biatrial electroanatomic mapping during sinus rhythm and distal coronary sinus (CS) pacing.
  • Assessed direction-dependent changes in conduction velocity, electrogram complexity, and voltage.

Main Results:

  • Direction-dependent conduction abnormalities were observed in both lone AF and reference groups.
  • Lone AF patients showed amplified abnormalities, including slower conduction, prolonged activation times, increased conduction block, and reduced voltage during distal CS pacing.
  • These changes were statistically significant compared to reference patients.

Conclusions:

  • Marked direction-dependent conduction abnormalities are present in lone AF.
  • These findings elucidate the interaction between abnormal atrial substrate and wavefront direction in lone AF.
  • Direction-dependent conduction may contribute to the higher arrhythmogenicity of left atrial ectopic triggers.