left 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 1st heart sound–HS and reversed splitting of 2nd 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.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

left bundle branch block

Abbreviation: LBBB
A defect in the conduction system of the heart in which electrical conduction down the left bundle branch is delayed. On the 12-lead EKG, it gives the QRS complex a widened QS complex in lead V1 (0.12 sec.).
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
In patients with atrioventricular septal defect, the left anterior fascicle is hypoplastic and longer than usual, features that probably account for the pattern of left anterior fascicular block so commonly seen.
Left anterior fascicular block was found in electrocardiogram (ECG).
DIAGNOSIS: Isorhythmic dissociation of an accelerated junctional rhythm from sinus rhythm, left anterior fascicular block, left ventricular hypertrophy with repolarization change.

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