Right Bundle Branch Block: Symptoms, Causes & Treatment

Right bundle branch block (RBBB) is a change in the heart’s electrical conduction that causes the electrical impulse to travel more slowly through the right side of the heart. As a result, the right ventricle contracts slightly later than the left ventricle.

In most cases, right bundle branch block is not serious, but it can be associated with heart or lung conditions, such as myocarditis or a blood clot in the lungs. When an underlying condition is present, symptoms may include feeling faint or having heart palpitations.

Right bundle branch block is detected with an electrocardiogram (ECG) and usually does not require treatment. However, if an underlying condition is present, a cardiologist may prescribe medication or, in more severe cases, recommend a cardiac device.

Main symptoms

Right bundle branch block usually does not cause symptoms. However, when it is associated with heart or lung disease, symptoms may include:

• Dizziness

• Fainting or feeling like you are about to faint

• Heart palpitations

• Shortness of breath

• Chest pain

Although these symptoms can have many causes, frequent or increasingly severe symptoms may be a sign of a heart or lung problem, even if they are not directly caused by right bundle branch block.

Read more about heart disease symptoms and when to see a doctor.

Is it dangerous?

Isolated right bundle branch block is rarely dangerous and generally does not cause death. The risk is higher when it is associated with serious heart or lung disease that can lead to arrhythmias or heart failure.

Main types

Right bundle branch block may be described according to how much electrical conduction through the right bundle is affected:

• Incomplete right bundle branch block: electrical conduction through the right side is delayed, but the ECG findings do not meet the criteria for complete right bundle branch block. It usually does not cause symptoms and may be found in otherwise healthy people.

• Intermittent right bundle branch block: the conduction abnormality occurs only at certain times and may alternate with periods of normal conduction.

• Complete right bundle branch block: electrical conduction through the right bundle is fully interrupted, so the right ventricle is activated through an alternate pathway after the left ventricle.

The clinical significance of right bundle branch block depends on the extent of the conduction abnormality and whether an underlying heart or lung condition is present.

Right vs left bundle branch block

With right bundle branch block, the left ventricle is activated before the right ventricle. With left bundle branch block, activation of the left ventricle is delayed instead.

When conduction abnormalities affect more than one part of the heart’s ventricular conduction system, electrical conduction can become more impaired, increasing the risk of clinically significant rhythm or conduction problems.

Confirming a diagnosis

Right bundle branch block is diagnosed by a cardiologist, who evaluates symptoms and medical history and performs an electrocardiogram (ECG) to identify abnormalities in the heart’s electrical conduction.

According to the American Heart Association, bundle branch block can be identified on an ECG by characteristic changes in the heart’s electrical activity.

When necessary, the doctor may also order additional tests, such as an echocardiogram, chest X-ray, or exercise stress test, to look for underlying heart or lung conditions.

Possible causes

Possible causes of right bundle branch block include:

• Myocardial infarction (heart attack)

• Myocarditis

• Congenital heart defects, such as an atrial septal defect (ASD)

• Cardiomyopathy or other changes affecting the heart muscle

• Pulmonary embolism

• Pulmonary hypertension

• Cor pulmonale

Risk factors associated with right bundle branch block may also include aging, hyperkalemia, which is an abnormally high potassium level in the blood, and high blood pressure, which places additional strain on the heart.

Right bundle branch block may also occur after certain heart procedures if interventions such as right heart catheterization, heart surgery, or cardiac ablation affect the right bundle.

However, right bundle branch block can also occur without an identifiable cause and may be found in healthy people with no known heart or lung disease.

Treatment options

In most cases, right bundle branch block itself does not require treatment and only needs medical follow-up. However, when an underlying condition or significant symptoms are present, treatment may include:

1. Treating the underlying cause

When right bundle branch block is linked to high blood pressure, heart failure, or lung disease, treatment focuses on managing that condition.

According to the American Heart Association, treatment may be needed if bundle branch block is associated with another heart problem or significant conduction abnormalities.

A cardiologist may prescribe blood pressure medications such as captopril, bisoprolol, or, in selected cases, digoxin.

2. Cardiac devices

In more severe cases, particularly when right bundle branch block occurs with a more significant conduction disorder or serious structural heart disease, a doctor may recommend a cardiac device, such as a(n):

• Pacemaker: may be recommended when a significant conduction disorder causes symptomatic bradycardia, fainting, or advanced heart block.

• Implantable cardioverter-defibrillator (ICD): may be recommended for certain people at high risk of life-threatening arrhythmias or sudden cardiac death, including some people with cardiomyopathy.

• Cardiac resynchronization therapy (CRT): may be considered for selected people with heart failure and significant ventricular conduction delay who meet the criteria for this treatment.

These devices can help manage significant conduction or rhythm problems, protect the heart, and improve quality of life when medically indicated.