Left anterior fascicular block

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Left anterior fascicular block
ECG showing left anterior fascicular block
Synonyms	Left anterior hemiblock
Pronounce	N/A
Specialty	N/A
Symptoms	Often asymptomatic, may cause syncope or dizziness
Complications	Complete heart block, arrhythmias
Onset	Typically in adults
Duration	Chronic
Types	N/A
Causes	Hypertension, coronary artery disease, aortic stenosis
Risks	Age, hypertension, ischemic heart disease
Diagnosis	Electrocardiogram (ECG)
Differential diagnosis	Left bundle branch block, right bundle branch block
Prevention	Control of risk factors such as hypertension and coronary artery disease
Treatment	Usually none required, treat underlying conditions
Medication	N/A
Prognosis	Generally good if isolated
Frequency	Common in older adults
Deaths	N/A

Left anterior fascicular block

A Left Anterior Fascicular Block (LAFB) is an electrocardiographic finding characterized by a slightly widened QRS duration.

Pathophysiology

LAFB occurs due to a conduction delay or blockage in the left anterior fascicle of the heart's ventricular conduction system, leading to altered electrical activity.

ECG Characteristics

Key ECG features of LAFB include:

• Slightly widened QRS complex (typically <120 ms)
• Left axis deviation
• Small q waves and tall R waves in the lateral leads

Causes

LAFB can be associated with:

• Hypertensive heart disease
• Aortic stenosis
• Cardiomyopathies
• Myocardial infarction
• Degenerative changes in the conduction system

Clinical Significance

While LAFB itself usually does not cause symptoms, it can be indicative of underlying heart disease and may affect the interpretation of the ECG in the context of myocardial ischemia.

Diagnosis

Diagnosis of LAFB is primarily based on ECG findings. Additional tests might include echocardiography or MRI to assess structural heart abnormalities.

Treatment

LAFB does not typically require specific treatment but managing underlying conditions is crucial. Regular cardiac evaluation is recommended.

Prognosis

The prognosis of LAFB varies depending on the associated cardiac conditions.

Epidemiology

LAFB is more commonly seen in older adults and those with hypertension or other forms of heart disease.

See Also

• Bundle branch block
• Electrocardiography
• Cardiac arrhythmia

External Links

• American Heart Association - Understanding Your EKG
• Medscape - Left Anterior Fascicular Block

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