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Related Concept Videos

Disturbances in Heart Rhythm01:28

Disturbances in Heart Rhythm

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

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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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Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers01:24

Antiarrhythmic Drugs: Class II Agents as β-Adrenergic Blockers

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Adrenergic stimulation generally impacts cardiac rate and rhythm. Specifically, stimulation of the β-adrenoceptors triggers an increase in intracellular calcium ion influx and pacemaker currents, which may cause arrhythmias. Catecholamines like adrenaline also demonstrate β2-adrenoceptor-mediated hypokalemia, impacting cardiac action potential and disrupting the normal cardiac rhythm. Class II antiarrhythmic drugs are β-adrenoceptor antagonists or β-blockers, which...
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The Cardiac Cycle01:13

The Cardiac Cycle

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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...
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Arrhythmias are disturbances in the heart's rhythm that lead to abnormal heartbeats. These irregularities can originate from different parts of the heart and are classified based on their origin and nature.
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism,...
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Cardiac Action Potential01:30

Cardiac Action Potential

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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
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Pseudo-2:1 bundle branch block. "Fusion causes confusion".

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  • 1University of Rochester School of Medicine and Dentistry Rochester New York USA.

Journal of Arrhythmia
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Summary

Differentiating electrocardiogram (ECG) patterns is crucial. Narrow-QRS sinus beats fused with ventricular extrasystoles can mimic parasystole, not 2:1 right bundle branch block (RBBB).

Keywords:
bundle branch blockend‐diastolic ventricular extrasystoleparasystoleventricular fusion

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Diagnostics

Background:

  • Electrocardiography (ECG) is essential for diagnosing cardiac arrhythmias.
  • Distinguishing between similar ECG patterns can be challenging, impacting patient management.
  • Ventricular extrasystoles and parasystole present unique diagnostic considerations.

Purpose of the Study:

  • To clarify the ECG differentiation between sinus beats fused with ventricular extrasystoles and parasystole.
  • To highlight potential misinterpretations of specific ECG findings.
  • To emphasize the importance of PR interval variability in diagnosis.

Main Methods:

  • Analysis of electrocardiographic recordings featuring narrow-QRS sinus beats and end-diastolic ventricular extrasystoles in bigeminy.
  • Comparison of the observed ECG patterns with established criteria for parasystole and 2:1 right bundle branch block (RBBB).

Main Results:

  • The fusion of sinus beats with ventricular extrasystoles can create an ECG pattern resembling parasystole.
  • This pattern should not be misdiagnosed as 2:1 RBBB due to inconsistent PR intervals.
  • Variability in PR intervals is a key differentiator.

Conclusions:

  • The described ECG pattern necessitates careful interpretation to avoid misdiagnosis.
  • Understanding the interplay between sinus beats and ventricular extrasystoles is critical for accurate arrhythmia identification.
  • PR interval analysis is vital for differentiating these conditions.