Overview of Right Bundle Branch Block

Right bundle branch block (RBBB) is an abnormal pattern seen on an electrocardiogram (ECG). It indicates that the heart’s electrical impulse is not being distributed normally across the ventricles, the chambers that pump blood out of the heart.

Specifically, right bundle branch block means that the electrical stimulation of the right ventricle is being delayed. The right ventricle pumps blood to the lungs.

This article discusses the causes of right bundle branch block and what it may mean to someone's future health. It also explains how underlying heart or lung disease may play a role in the diagnosis.

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.

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.

Right, Left Branches Are Similar

Bundle branch block affects how efficiently the heart can pump blood. It is similar to left bundle branch block (LBBB), in which the stimulation of the left ventricle is delayed. 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.

Significance

Right bundle branch block is more common than left bundle branch block and appears to be less serious. However, right bundle branch block indicates a higher risk for heart disease and, sometimes, the eventual need for a pacemaker.

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

The risk 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. It is also more common in men.

Underlying Heart and Lung Disease

As it courses within the muscle of the right ventricle, the right bundle branch is relatively close 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:

  • Atrial septal defect, a hole in the wall between the two upper chambers of the heart)
  • Coronary artery disease (CAD), in which blood flow to the heart muscle is reduced
  • Myocarditis, inflammation of the cardiac muscle
  • Valvular heart disease, involving one or more of the four heart valves
  • Ventricular septal defect, a hole in the heart

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, in which a blood clot lodges in the lung and blocks blood flow to part of the lung.

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.

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, even this transient right bundle branch block will likely create a 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.

The Efficiency of the Heartbeat

With either right or left bundle branch block, the heart's two ventricles are 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.

Diagnosis

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

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's usually easy to determine the presence of right bundle branch block by simply noting the widening pattern of the QRS complex.

Sometimes, right bundle branch block is part of Brugada syndrome, a rare but potentially life-threatening heart rhythm disorder. 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 is considered a possibility.

Indications for a Pacemaker

By itself, right bundle branch block 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 (a slow heart rate) or heart block should develop.

Summary

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. Right bundle branch block (RBBB) is an abnormal pattern seen on an ECG. It means that there is a partial or complete blockage of the electrical impulse to the right ventricle, which delays its electrical activation and, therefore, its contraction.

Right bundle branch block is sometimes associated with an underlying cardiac or pulmonary condition. It can be classified as either a complete block or an incomplete block. An incomplete block means that electrical signals are being conducted better than in a complete block. Still, right bundle branch block indicates a higher risk for heart disease and, sometimes, the eventual need for a pacemaker.

A Word From Verywell

Even in people without any heart problems, right bundle branch block indicates an increased cardiovascular risk. It's vital to be under the care of a healthcare provider who can help you minimize the risk factors you can control, like dietary and exercise habits.

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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.
  1. Rasmussen PV, Skov MW, Ghouse J, et al. Clinical implications of electrocardiographic bundle branch block in primary care. Heart. 2019;105(15):1160-1167. doi:10.1136/heartjnl-2018-314295.

  2. University of Rochester Medical Center. Health Encyclopedia: About the Heart and Blood Vessels.

  3. Surawicz B, Childers R, Deal BJ, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology. J Am Coll Cardiol. 2009; 53:976. doi:10.1016/j.jacc.2008.12.013

  4. Alventosa-Zaidin M, Guix Font L, Benitez Camps M, et al. Right bundle branch block: Prevalence, incidence, and cardiovascular morbidity and mortality in the general population. European Journal of General Practice. 2019;25(3):109-115. doi:10.1080/13814788.2019.1639667.

  5. Jeong JH, Kim JH, Park YH, et al. Incidence of and risk factors for bundle branch block in adults older than 40 years. Korean J Intern Med. 2004;19(3):171-178. doi:10.3904/kjim.2004.19.3.171

  6. Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Journal of the American College of Cardiology. 2019;74(7):932-987. doi:10.1016/j.jacc.2018.10.044.

  7. Henin M, Ragy H, Mannion J, David S, Refila B, Boles U. Indications of cardiac resynchronization in non-left bundle branch block: Clinical review of available evidence. Cardiol Res. 2020;11(1):1-8. doi:10.14740%2Fcr989.

  8. Francis J, Antzelevitch C. Brugada syndrome. International Journal of Cardiology. 2005;101(2):173-178. doi:10.1016/j.ijcard.2004.03.068.

Additional Reading

By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.