Overview of Right Bundle Branch Block

Right bundle branch block (RBBB) is an abnormal pattern that is seen on the electrocardiogram (ECG), which indicates that the heart’s electrical impulse is not being distributed normally across the ventricles. Specifically, right bundle branch block means that the electrical stimulation of the right ventricle is being delayed.

Causes of Right Bundle Branch Block
Verywell / Gary Ferster

Causes

The two bundle branches (right and left) are the electrical pathways that allow the cardiac electrical impulse to spread rapidly and evenly through both ventricles so that the beating of the heart is well-coordinated.

With right bundle branch block, there is a partial or complete blockage of the electrical impulse to the right ventricle, which delays its electrical activation and, therefore, its contraction.

Similar to left bundle branch block (LBBB), in which the stimulation of the left ventricle is delayed), right bundle branch block affects how efficient the heart can pump blood. Because the right side of the heart moves blood to the lungs instead of the entire body, RBBB carries a lower risk of death than LBBB.

Right bundle branch block is sometimes associated with an underlying cardiac or pulmonary condition. When right bundle branch block is diagnosed, a medical evaluation is usually required to uncover and reduce cardiovascular risks.

Diagnosis

Right bundle branch block causes a characteristic change on the ECG, so doctors can usually readily diagnose this condition simply by examining the results.

In bundle branch block, the QRS complex—the portion of the ECG that represents the electrical impulse traveling across the ventricles—is wider than normal, since it takes longer than normal for the impulse to be distributed.

In right bundle branch block, there is a characteristic pattern this widening takes across the 12 leads (or “views”) provided by a standard ECG. So, it is usually easy to determine the presence of right bundle branch block by simply taking note of the pattern of widening of the QRS complex.

Sometimes, right bundle branch block is part of Brugada syndrome. If the ECG in a young person shows a pattern suggestive of right bundle branch block accompanied by elevation in the ST-segments in leads V1 and V2, especially if there also is a history of unexplained episodes of syncope or lightheadedness, Brugada syndrome should be considered as a possibility.

Significance

The incidence of right bundle branch block increases with age. It occurs twice as often in people over age 65 as compared to those over age 40 and is more common in men.

Right bundle branch block is more common than left bundle branch block and may be less serious. However, right bundle branch block does indicate a higher risk for heart disease and eventually needing a pacemaker.

When right bundle branch block is detected, it can be classified as either a complete block or an incomplete block based on ECG findings. An incomplete block means that electrical signals are being conducted better than in a complete block.

Because an incomplete block can sometimes progress to a complete block, ongoing monitoring is recommended. However, an incomplete block generally does not pose a risk on its own.

Underlying Heart and Lung Disease

The right bundle branch, as it courses within the muscle of the right ventricle, is relatively superficial to the surface of the ventricular cavity. This makes the right bundle branch susceptible to damage and stretching whenever the right ventricle is placed under stress of any kind.

Right bundle branch block will often occur with any condition that affects the right ventricle. These conditions can include:

Right bundle branch block may also be seen with any condition that raises pressure in the right ventricle.

The most common one that does this is a pulmonary embolus, but lung conditions that cause chronic elevation in pressures within the right ventricle are also of concern. Conditions like chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea, for example, can cause pulmonary hypertension that can lead to right bundle branch block.

Anyone who is discovered to have right bundle branch block needs a medical evaluation that concentrates on signs of heart or lung disease. A chest X-ray and an echocardiogram are commonly-used screening tools for this purpose.

Because the right bundle branch is susceptible to anything that can produce even small trauma in the right ventricle, transient right bundle branch block occurs occasionally in patients undergoing cardiac catheterization. This temporary case occurs when the catheter irritates the right bundle branch. It usually resolves quickly (within minutes) once the catheter is removed.

However, in people who already have left bundle branch block, causing even this transient right bundle branch block will likely create temporary complete heart block, and the heart can stop beating. As such, those having a right-sided cardiac catheterization sometimes get a temporary pacemaker inserted during the procedure to assure that the heart rhythm will continue uninterrupted during the study.

The Efficiency of the Heartbeat

With either right or left bundle branch block, the heart's two ventricles are being stimulated in sequence (one after the other) instead of simultaneously. This loss of normal coordination between the two ventricles can reduce the efficiency of the heartbeat.

However, the reduction in the heart's efficiency is probably less important in right bundle branch block. So, for instance, the use of cardiac resynchronization therapy (CRT) may not be as helpful in people with right bundle branch block, even if they have heart failure.

Indications for a Pacemaker

Right bundle branch block, by itself, does not require treatment with a permanent pacemaker. However, in some people, right bundle branch block is just one manifestation of a more general problem with the heart’s electrical conduction system.

In such cases, a pacemaker may eventually be required if sick sinus syndrome or heart block should develop.

A Word From Verywell

Right bundle branch block, even in people without any heart problems, indicates increased cardiovascular risk. Anyone who is found to have it should have a screening evaluation to rule out underlying heart or lung disease, and minimize the cardiovascular risk factors they can control.

Right bundle branch block is especially serious in people who already have heart failure or have had a heart attack.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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