An Overview of Right Bundle Branch Block

When Is RBBB a Problem?

right bundle branch block
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Right bundle branch block 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.

What Causes Right Bundle Branch Block?

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. Right bundle branch block delays the electrical activation of the right ventricle. Subsequently, the right ventricle is stimulated after the left ventricle is stimulated, and its contraction is delayed.

In contrast to left bundle branch block (in which the stimulation of the left ventricle is delayed), right bundle branch block does not compromise overall cardiac function in any measurable way. So right bundle branch block itself is usually regarded as a benign condition that does not require any specific therapy.

However, right bundle branch block is still an important finding. Its significance lies in the fact it is often associated with some underlying cardiac or pulmonary condition. So when right bundle branch block is diagnosed, a medical evaluation is usually required.

Diagnosing Right Bundle Branch Block 

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

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, simply by taking note of the pattern of widening of the QRS complex, it is usually easy to determine the presence of right bundle branch block.

Why Is Right Bundle Branch Block Significant?

The incidence of right bundle branch block increases with age. It is seen only rarely in young people, but more than 11 percent of 80-year-old people have right bundle branch block.

Right bundle branch block is more common, and medically is much less significant, than its counterpart, left bundle branch block. When right bundle branch block is detected, the chief concern should be to do an evaluation to look for an underlying cardiac or pulmonary condition.

If no such condition is found, the right bundle branch block generally can be considered completely benign (not harmful).

Right Bundle Branch Block and 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.

So, right bundle branch block will often occur with any condition that affects the right ventricle. These conditions can include coronary artery disease (CAD)myocarditis (inflammation of the cardiac muscle), atrial septal defect, ventricular septal defect, and valvular heart disease.

Furthermore, right bundle branch block may also be seen with any lung condition that causes a chronic elevation in the pressures within the right ventricle, especially pulmonary hypertension. Pulmonary hypertension, in turn, can be caused by an array of various lung disorders, including  chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea.

To note, right bundle branch block is common with any condition that acutely raises pressures in the right ventricle. The most common condition that does this is a pulmonary embolus.

As a result, 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 in approximately 5 percent of patients undergoing cardiac catheterization. This temporary right bundle branch block occurs when the catheter irritates the right bundle branch. This transient bundle branch block 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. So, in people with left bundle branch block who are having a right-sided cardiac catheterization, sometimes a temporary pacemaker is inserted during the procedure, to assure that the heart rhythm will continue uninterrupted during the study.

Right Bundle Branch Block and 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 heart beat.

However, the reduction in the heart's efficiency is trivial and of no consequence in right bundle branch block. So, for instance, the use of cardiac resynchronization therapy (CRT) is not recommended in people with right bundle branch block, even if they have heart failure.

Does Right Bundle Branch Block Require a Pacemaker?

Right bundle branch block, by itself, never requires treatment with a permanent pacemaker. However, in some people right bundle branch block does not occur by itself, but instead represents 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 itself is a benign condition that requires no treatment. However, anyone who is found to have it should have a screening evaluation to rule out underlying heart or lung disease. If none is found, then the right bundle branch block usually can be written off as an incidental finding, with no important medical significance.

Sources:

Badheka AO, Singh V, Patel NJ, et al. QRS Duration on Electrocardiography and Cardiovascular Mortality (from the National Health and Nutrition Examination Survey-III). Am J Cardiol 2013; 112:671.

Barsheshet A, Goldenberg I, Garty M, et al. Relation of Bundle Branch Block to Long-term (Four-year) Mortality in Hospitalized Patients With Systolic Feart failure. Am J Cardiol 2011; 107:540.

Bussink BE, Holst AG, Jespersen L, et al. Right bundle Branch Block: Prevalence, Fisk factors, and Outcome in the General Population: Results From the Copenhagen City Heart Study. Eur Heart J 2013; 34:138.

Zhang ZM, Rautaharju PM, Soliman EZ, et al. Mortality Risk Associated With Bundle Branch Blocks and Related Repolarization Abnormalities (From the Women's Health Initiative WHI). Am J Cardiol 2012; 110:1489.

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