left bundle branch block


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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.

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.

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.).
References in periodicals archive ?
Should the electrocardiogram be used to guide therapy for patients with left bundle branch block and suspected acute myocardial infarction?
Comorbidity and myocardial dysfunction are the main explanations for the higher 1-year mortality in acute myocardial infarction with left bundle branch block.
His electrocardiogram showed alternating right and left bundle branch blocks without PR or ST interval changes.
In patients with left bundle branch block, who represented 70 percent of the study group, CRT-D showed a reduction in the risk of death and heart failure by 57 percent, as compared to ICD alone.
Left bundle branch block (LBBB) can mask the ECG signature of acute or chronic myocardial ischemia or infarction.
Patients in Emergency Departments (ED) with suspected myocardial infarction (MI), commonly referred to as a heart attack, frequently have a diffuse 12-lead ECG abnormality known as Left Bundle Branch Block (LBBB).
After the administration of amiodarone, the runs of tachycardia were briefer, the rate was slower, and rate-related left bundle branch block was seen less frequently (Figure 2).
An AV block and a left bundle branch block were simulated with 100%, 80% and 60% interventricular conduction velocity.
Food and Drug Administration for the expansion of its CRT-D indication to include high-risk(2) NYHA Class I and II patients with Left Bundle Branch Block.
A preoperative electrocardiogram did not show left bundle branch block but did show a long P-R interval and left ventricular hypertrophy (Figure 2) (3).