It is considered an abnormal finding on anelectrocardiogram (ECG).
LBBB doesn’t always indicate a problem with your heart, especially if you have no underlying health conditions.
This article explains the symptoms, causes, diagnosis, and treatment of LBBB.
Verywell / Laura Porter
They are the pathways that spread the heart’s electrical impulse evenly through theventriclesof the heart.
This ensures that the ventricles contract (beat) in a coordinated way.
This blockage delays the contraction of the left ventricle.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
As a consequence, the right ventricle contracts before the left one.
For the heart to beat efficiently, both ventricles should contract simultaneously.
As such, left bundle branch block can reduce the efficiency of the heartbeat.
In someone whose heart is otherwise healthy, this reduced function may be trivial.
This reduced efficiency can accelerate the deterioration of heart failure and make symptoms significantly worse.
Symptoms
Most people with LBBB do not experience symptoms directly related to LBBB.
Symptoms may include:
Causes
LBBB may develop without any specific cause.
However, it is often associated with a variety of heart problems.
As the heart muscle tries to compensate for this weakness, it stretches and becomes enlarged.
LBBB can be both a cause of dilated cardiomyopathy and a result of it.
Most of the time, healthcare providers can’t identify a cause for dilated cardiomyopathy.
Diagnosis
Left bundle branch block produces characteristic changes on an ECG.
Healthcare providers are typically able to diagnose this condition by examining these test results.
The standard ECG recording shows 12 different views of the heart’s electrical activity.
Ten electrodes (or “leads”) that are attached to the body transmit these images.
However, the QRS complex is much wider with left bundle branch block, often greater than 0.12 seconds.
Differential Diagnoses
Most people with left bundle branch block have some form of underlying heart disease.
About one-third of people with heart failure also have LBBB.
Treatment
For people without underlying heart disease, treatment may not be necessary.
CRT
CRT is a pop in of pacemaker that re-coordinates the contraction of the ventricles.
It can improve the heart’s efficiency in people with LBBB and heart failure.
If you have an underlying heart condition, the heart’s electrical signal can become disrupted in several ways.
When that happens, significantbradycardia(slow heart rate) may develop.
Your healthcare provider will want to do regular evaluations of your heart to double-check it remains healthy.
Is LBBB Reversible?
LBBB doesn’t resolve on its own.
Preventing LBBB
Left bundle branch block can’t always be prevented.
Often, but not always, the presence of LBBB indicates an underlying heart condition.
Healthcare providers diagnose LBBB during an ECG.
If no underlying heart condition is present, you may not need treatment.
If LBBB is identified, cardiac electrical impulses are not following a normal distribution pattern across the ventricles.
This can be a sign of underlying heart disease.
A left bundle branch block can indicate a severe heart condition, or it can be benign.
On its own, LBBB does not seem to shorten your lifespan.
When combined with other risk factors, LBBB is associated with an increased risk of death.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
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