Right & Left Bundle Branch Block | MedStar Health

Two conditions that affect the electrical impulses in your heart

The bundle branches are two pathways that carry electrical impulses to the muscular walls of the two lower heart chambers, or ventricles. These electrical impulses tell the heart walls when to contract and pump blood through the heart.

Bundle branch blocks occur when the electrical impulses travel too slowly through the pathways. This can make it harder for your heart to pump blood throughout the body. It can sometimes cause fainting or increase your risk of complications after a heart attack.

Most people with this condition don’t feel any symptoms, and if you don’t have an underlying condition that’s causing it, you likely will not need treatment.

They are categorized by which side of the heart is affected.

Right bundle branch block

Right bundle branch block (RBBB) affects the right lower heart chamber. RBBB is common and can occur in otherwise healthy hearts.

If you don’t have an additional heart condition, treatment of RBBB usually is not necessary. However, if you have an underlying condition that is causing the RBBB, you may require treatment for that condition.

Conditions that may cause RBBB include:

Developing RBBB may be a signal that your heart condition is worsening or your heart muscle is seriously damaged. The risk of developing RBBB increases as you age.

Left bundle branch block

Left bundle branch block (LBBB) affects the lower left heart chamber and is less common than RBBB. Rarely, LBBB can appear in healthy hearts and doesn’t require treatment if no additional heart condition is present.

As you age, you are more likely to develop LBBB associated with a heart condition. Some of the conditions that may cause LBBB include:

LBBB can interfere with an electrocardiogram, making it more difficult for your doctor to diagnose other conditions like left ventricular hypertrophy. Be sure to tell your doctor about your LBBB if you undergo a stress test or experience a heart attack.



An echocardiogram uses high-frequency sound waves to create images of your heart.

Electrocardiogram (ECG)

An electrocardiogram, also known as an ECG, measures the heart’s electrical activity.

Event Monitors

An event monitor is a small device that records the heart’s electrical activity. It’s similar to an electrocardiogram, but where an electrocardiogram takes place over a few minutes, an event monitor measures heart rhythms over a much longer time.

Holter Monitors

A Holter monitor is a small device that records the heart’s electrical activity. It’s similar to an electrocardiogram, but whereas an electrocardiogram records over a few minutes, a Holter monitor records over the course of a day or two.

Loop Recorder

A loop recorder is a device that’s implanted underneath the skin of your chest to record your heart rhythm for up to three years.


Bundle branch block typically does not need treatment if you don’t have an underlying heart condition. If you are diagnosed with another heart condition, your physician team will work with you to develop and implement a treatment plan.

Arrhythmia Treatments (Heart Rhythm)
Treatments for arrhythmias, or heart rhythm disorders, such as minimally invasive procedures, implantable devices and surgery, vary based on the type and severity of your condition.


Have questions for our heart and vascular program? Email us at AskMHVI@medstar.net.