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Related Concept Videos

Disturbances in Heart Rhythm01:29

Disturbances in Heart Rhythm

2.2K
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...
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ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias01:25

ECG Interpretation of Arrhythmias II: Atrial, Junctional and Ventricular Arrhythmias

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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...
319
Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

289
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...
289
Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

357
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...
357
Dysrhythmias II: Classification of Tachyarrhythmias01:28

Dysrhythmias II: Classification of Tachyarrhythmias

362
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...
362
Mechanism of Cardiac Arrhythmias01:28

Mechanism of Cardiac Arrhythmias

1.5K
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.
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Related Experiment Video

Updated: Dec 11, 2025

Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice
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Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice

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"Unreasonable" ventricular pacings.

Yubin Zhang1, Tong Liu2, Panagiotis Korantzopoulos3

  • 1The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.

Annals of Noninvasive Electrocardiology : the Official Journal of the International Society for Holter and Noninvasive Electrocardiology, Inc
|August 22, 2020
PubMed
Summary
This summary is machine-generated.

This case highlights pacemaker ECG interpretation challenges. We analyze ventricular pacing (VP) in a patient with stable intrinsic atrioventricular (AV) conduction, clarifying diagnostic reasoning.

Keywords:
electrocardiographyimplantable devicesnoninvasive techniquespacemaker mediated tachycardia

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Medical Device Technology

Background:

  • A 66-year-old male patient with a history of an Abbott dual-chamber pacemaker implantation presented with recurrent palpitations.
  • The patient maintained stable intrinsic atrioventricular (AV) conduction, posing a diagnostic dilemma regarding observed ventricular pacing (VP) on electrocardiogram (ECG).

Observation:

  • Electrocardiogram (ECG) analysis revealed unexpected ventricular pacing (VP) despite the presence of intact intrinsic atrioventricular (AV) conduction.
  • This discrepancy between pacemaker function and native cardiac rhythm presented a diagnostic challenge for the attending medical team.

Findings:

  • The case focuses on the logical reasoning process required to interpret pacing ECGs in complex clinical scenarios.
  • Detailed analysis of the ECG findings is crucial for understanding the interplay between the pacemaker and the heart's native electrical activity.

Implications:

  • Accurate interpretation of pacemaker ECGs is essential for appropriate device management and patient care.
  • Understanding the mechanisms behind unexpected pacing modes can prevent misdiagnosis and guide therapeutic interventions in patients with cardiac implantable electronic devices.