left bundle branch block (redirected from Left posterior fascicular block)

left bundle branch block (LBBB),

the failure of the cardiac impulse to propagate down the left bundle branch from the bundle of His, resulting in early activation of the right side of the septum and the right ventricular myocardium. See also bundle branch block.

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left bundle branch block

Cardiology A condition in which ventricular contraction is not completely synchronized due to a block in conduction of an electrical impulse to the ventricles; in LBBB, right ventricular endocardial activation begins before, and is often completed before, initiation of left ventricular endocardial activation; benign LBBB is rare; preexisting LBBB in absence of clinical evidence of heart disease is rare; newly acquired LBBB has a 10-fold ↑ in mortality Clinical Generally asymptomatic, or absent or diminished 1^st heart sound–HS and reversed splitting of 2^nd HS EKG Lead V₁–QS or rS; lead V₆–late intrinsicoid deflection, monophasic R; lead I–monophasic R Management Pacemaker, if syncope or significant arrhythmias Followup Telemetry PRN. See Bundle branch block. Cf Right bundle branch block.