Bifascicular block is a conduction abnormality in the
heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to ...
where two of the three main
fascicles of the
His/Purkinje system are blocked.
Most commonly, it refers to a combination of
right bundle branch block
A right bundle branch block (RBBB) is a heart block in the right bundle branch of the electrical conduction system.
During a right bundle branch block, the right ventricle is not directly activated by impulses travelling through the right bund ...
(RBBB) and either
left anterior fascicular block
Left anterior fascicular block (LAFB) is an abnormal condition of the left ventricle of the heart, related to, but distinguished from, left bundle branch block (LBBB).
It is caused by only the left anterior fascicle – one half of the left bund ...
(LAFB) or
left posterior fascicular block
A left posterior fascicular block (LPFB), also known as left posterior hemiblock (LPH), is a condition where the left posterior fascicle, which travels to the inferior and posterior portion of the left ventricle, does not conduct the electrical ...
(LPFB), with the former being more common.
Some authors consider
left bundle branch block
Left bundle branch block (LBBB) is a conduction abnormality in the heart that can be seen on an electrocardiogram (ECG). In this condition, activation of the left ventricle of the heart is delayed, which causes the left ventricle to contract lat ...
(LBBB) to be a technical bifascicular block, since the block occurs above the
bifurcation
Bifurcation or bifurcated may refer to:
Science and technology
* Bifurcation theory, the study of sudden changes in dynamical systems
** Bifurcation, of an incompressible flow, modeled by squeeze mapping the fluid flow
* River bifurcation, the for ...
of the left anterior and left posterior fascicles of the left bundle branch.
Diagnosis
Diagnostic criteria:
Clinically, bifascicular block presents with one of two ECG patterns:
Right bundle branch block (RBBB) with left anterior fascicular block (LAFB), manifested as
left axis deviation (LAD).
RBBB and left posterior fascicular block (LPFB), manifested as
right axis deviation (RAD) in the absence of other causes.
Treatment
In those with bifascicular block and no symptoms, little with respect to treatment is needed. In those with
syncope, a
pacemaker
An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart eith ...
is recommended.
References
Olshansky B. Bradyarrhythmias – Conduction System Abnormalities. In: Arrhythmia Essentials 2e, 2017.
Vijayaraman P. Clinical Cardiac Pacing, Defibrillation and Resynchronisation Therapy 5e, 2017
Goldberger A. Ventricular Conduction Disturbances.. In: Goldberger’s Clinical Electrocardiography 9e, 2018.
External links
Cardiac arrhythmia
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