Atrioventricular block, second degree

Second-degree atrioventricular block
Synonyms	Second-degree AV block
Pronounce	N/A
Specialty	N/A
Symptoms	N/A
Complications	N/A
Onset	N/A
Duration	N/A
Types	N/A
Causes	N/A
Risks	N/A
Diagnosis	N/A
Differential diagnosis	N/A
Prevention	N/A
Treatment	N/A
Medication	N/A
Prognosis	N/A
Frequency	N/A
Deaths	N/A

Second-degree atrioventricular block (AV block) is a type of heart block in which there is a delay or interruption in the transmission of electrical impulses from the atria to the ventricles. This condition is classified into two types: Mobitz type I (Wenckebach) and Mobitz type II.

Types

Mobitz Type I (Wenckebach)

Mobitz Type I, also known as Wenckebach block, is characterized by a progressive prolongation of the PR interval on the ECG until a beat is dropped (i.e., a QRS complex is not conducted). This type of block is usually benign and often occurs at the level of the atrioventricular node.

Mobitz Type II

Mobitz Type II is characterized by sudden, unexpected failure of a P wave to conduct to the ventricles, without prior PR interval prolongation. This type of block is more serious and often occurs below the level of the AV node, in the His-Purkinje system. It can lead to more severe forms of heart block and may require pacemaker implantation.

Causes

Second-degree AV block can be caused by a variety of factors, including:

• Ischemic heart disease
• Myocarditis
• Cardiomyopathy
• Electrolyte imbalance
• Medications such as beta-blockers, calcium channel blockers, and digoxin

Symptoms

Symptoms of second-degree AV block may include:

• Dizziness
• Syncope (fainting)
• Palpitations
• Fatigue

Diagnosis

Diagnosis is typically made using an electrocardiogram (ECG), which can show the characteristic patterns of Mobitz Type I or Type II block. Holter monitor or event monitor may be used for further evaluation.

Treatment

Treatment depends on the type and severity of the block. Mobitz Type I may not require treatment if asymptomatic. Mobitz Type II often requires a pacemaker due to the risk of progression to complete heart block.

See also

• Atrioventricular block
• Heart block
• Pacemaker

External links

• Wikimd article on Second-degree AV block