Left Bundle Branch Block (LBBB)
Overview:
This infographic explains the etiology, risk factors, diagnostic criteria, mimics, and management strategies for Left Bundle Branch Block (LBBB). LBBB is a significant electrocardiographic abnormality indicating conduction delay through the left bundle branch, often linked to structural heart disease.
Etiology:
- Fibrosis and degeneration due to aging
- Myocardial pathology
- Compression of the left bundle branch
Risk Factors:
- Coronary artery disease
- Hypertension
- Myocarditis
- Cardiomyopathy
- Valvular and congenital heart disease
- Anterior myocardial infarction
Definition – AHA/ACC/HRS LBBB Criteria:
- QRS duration ≥120 ms
- Broad, slurred R wave in lateral leads (I, aVL, V5, V6)
- Absence of Q waves in leads I, V5, V6
- Prolonged R peak time in V5 and V6 >60 ms
- Initial small R wave in V1-V3
- Discordant ST/T waves opposite the QRS complex
Mimics:
- Paced rhythm
- Left ventricular hypertrophy (LVH)
- Wolff-Parkinson-White (WPW) syndrome
- Ventricular tachycardia (VT) originating from the right ventricular outflow tract
Management & Prognosis:
- Asymptomatic LBBB: Monitor for structural heart disease.
- LBBB with coronary artery disease (CAD): Associated with a higher risk of adverse cardiovascular outcomes.
- CRT (Cardiac Resynchronization Therapy) is beneficial in patients with LBBB and reduced ejection fraction (EF ≤35%).
- Close monitoring for progression to AV block is recommended, particularly in patients with TAVR or bundle branch reentrant ventricular tachycardia (BBRVT).
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This comprehensive resource provides a deeper understanding of the diagnostic and therapeutic implications of LBBB, equipping healthcare providers to improve clinical outcomes.
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