Overview
Left bundle branch block occurs due to failure of conduction down the left bundle branch, resulting in depolarisation of the left ventricle after the right ventricle.
Diagnosis
ECG Findings
- Wide QRS >120ms
- Broad R wave in lateral leads (I, aVL, V5, V6)
- Absent Q waves in I, V5 and V6
May be associated with left axis deviation, ST / T wave changes in the opposite direction to the QRS complex, or poor R wave progression.
Pathogenesis
Causes of Left Bundle Branch Block
- Ischaemic heart disease
- Hypertension
- Dilated cardiomyopathy
- Rheumatic heart disease
- Aortic stenosis
Next Page
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------