Atrioventricular block

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Atrioventricular block
Synonyms	AV block, heart block
Pronounce	N/A
Specialty	N/A
Symptoms	Bradycardia, syncope, dizziness, fatigue
Complications	Heart failure, sudden cardiac death
Onset	Any age, more common in older adults
Duration	Variable
Types	First-degree, second-degree (Mobitz I and II), third-degree
Causes	Myocardial infarction, cardiomyopathy, congenital heart disease, medications
Risks	Coronary artery disease, rheumatic fever, Lyme disease
Diagnosis	Electrocardiogram (ECG), Holter monitor
Differential diagnosis	Sick sinus syndrome, bundle branch block
Prevention	Management of risk factors, avoiding certain medications
Treatment	Pacemaker, medication adjustment
Medication	N/A
Prognosis	Varies by type and severity
Frequency	Common, especially in older adults
Deaths	Can be fatal if untreated

An Atrioventricular block (AV block) is a type of heart block where the conduction between the atria and ventricles of the heart is impaired. This condition can lead to recurrent sudden attacks of unconsciousness, known as syncope, due to irregular heartbeats.

Types

There are several types of AV block, classified based on the degree of impairment in the electrical conduction.

First-Degree AV Block

In a First-degree AV block, there is a delay in the conduction between the atria and ventricles but all signals eventually reach the ventricles.

Second-Degree AV Block

Second-degree AV block is subdivided into two types, Type I (Wenckebach) and Type II (Mobitz). Type I features progressive lengthening of conduction time until a beat is dropped. Type II is characterized by a sudden drop without prior lengthening.

Third-Degree AV Block

In Third-degree AV block, also known as complete heart block, there is no transmission of electrical signals from the atria to the ventricles.

ECG showing a Third-degree AV block.

Symptoms and Diagnosis

Symptoms of AV block can vary greatly depending on its type and severity, ranging from no symptoms to dizziness, fainting, or heart failure. Diagnosis typically involves an ECG to analyze the heart's electrical activity.

Causes

Causes of AV block include heart diseases such as myocardial infarction, congenital heart defects, certain medications, and degeneration of the electrical conduction system with age.

Treatment

Treatment depends on the type and severity of the block. Options include lifestyle changes, medication, and in some cases, the implantation of a pacemaker.

Epidemiology

The prevalence of AV block varies with age and underlying heart conditions. It is more common in the elderly and those with heart diseases.

See Also

• Cardiology
• Electrophysiology
• Heart arrhythmia

External Links

• American Heart Association - Atrioventricular Block
• National Center for Biotechnology Information - Atrioventricular Block