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Related Concept Videos

Dysrhythmias IV: Characteristics of Bradyarrhythmias01:18

Dysrhythmias IV: Characteristics of Bradyarrhythmias

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

Dysrhythmias II: Classification of Tachyarrhythmias

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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...
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Mechanism of Cardiac Arrhythmias01:28

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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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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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Dysrhythmias III: Characteristics of Dysrhythmias01:29

Dysrhythmias III: Characteristics of Dysrhythmias

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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...
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Optimization of Transesophageal Atrial Pacing to Assess Atrial Fibrillation Susceptibility in Mice
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Syncope and Idiopathic (Paroxysmal) AV Block.

Michele Brignole1, Jean-Claude Deharo2, Regis Guieu3

  • 1Department of Cardiology, Arrhythmologic Center, Ospedali del Tigullio, Via Don Bobbio 25, Lavagna 16033, Italy.

Cardiology Clinics
|June 28, 2015
PubMed
Summary

Idiopathic AV block causing syncope is linked to low adenosine levels, unlike vasovagal syncope. Cardiac pacing is an effective treatment for this condition.

Keywords:
Atrioventricular blockECGImplantable loop recorderSyncope

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Area of Science:

  • Cardiology
  • Electrophysiology
  • Internal Medicine

Background:

  • Syncope is a common clinical problem often caused by cardiac arrhythmias.
  • Idiopathic atrioventricular (AV) block is a rare cause of syncope characterized by intermittent complete heart block.
  • Understanding the underlying mechanisms of idiopathic AV block is crucial for effective management.

Purpose of the Study:

  • To characterize the clinical and electrocardiographic features of syncope due to idiopathic AV block.
  • To investigate the role of adenosine in the pathophysiology of idiopathic AV block.
  • To differentiate idiopathic AV block from other causes of syncope, such as vasovagal syncope.

Main Methods:

  • Prospective and retrospective analysis of patients with syncope.
  • Electrocardiogram (ECG) documentation, including prolonged ECG monitoring.
  • Measurement of baseline adenosine plasma levels (APL).
  • Assessment of patient history, cardiac examination, and response to pacing therapy.

Main Results:

  • Idiopathic AV block presents as paroxysmal complete heart block with pauses, unrelated to heart rate or ectopy.
  • Patients typically have a history of recurrent syncope without prodromes and no other cardiac abnormalities.
  • Low baseline adenosine plasma levels and increased sensitivity to exogenous adenosine were observed in patients with idiopathic AV block.
  • Adenosine plasma levels were significantly lower than in patients with vasovagal syncope.
  • Cardiac pacing proved effective in managing syncope in these patients.

Conclusions:

  • Idiopathic AV block is a distinct clinical entity characterized by specific ECG findings and a unique association with low adenosine levels.
  • Adenosine may play a role in the pathophysiology of idiopathic AV block, differentiating it from vasovagal syncope.
  • Cardiac pacing is a definitive treatment for syncope caused by idiopathic AV block.