Left bundle branch block (LBBB): ECG criteria, causes, management
Left bundle branch block (LBBB): ECG criteria and clinical implications Left bundle branch block (LBBB) is the consequence of anatomical or functional dysfunction in the left bundle branch, causing the impulse to be blocked. Depolarization of the left ventricle will be carried out by impulses spreading from the right ventricle. Because the left bundle branch is dysfunctional, the impulse will spread (through the left ventricle) partly or entirely outside of the conduction system; such impulse conduction is slow and therefore the QRS duration becomes prolonged. The hallmark of left bundle branch block (LBBB) is QRS duration ≥0,12 seconds, deep and broad S-wave in V1/V2 and broad clumsy R-wave in V5/V6. Refer to Figure 1 , where the difference between normal conduction, right bundle branch block ( RBBB ) and left bundle branch block (LBBB) is illustrated. Figure 1. These ECGs show the difference between normal conduction, left bundle branch block (LBBB) and right bundle branch block (RBBB). …
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