From the Guidelines
Right bundle branch block (RBBB) is a cardiac conduction abnormality that typically doesn't require specific treatment when found incidentally in otherwise healthy individuals. RBBB is diagnosed on an electrocardiogram (ECG) by characteristic findings including a widened QRS complex (>120 ms), an RSR' pattern in lead V1 (sometimes called "rabbit ears"), and wide S waves in leads I and V6. While isolated RBBB is often benign, it may indicate underlying heart disease in some cases, particularly when new-onset or accompanied by symptoms. Common causes include coronary artery disease, cardiomyopathy, congenital heart defects, pulmonary embolism, or myocarditis. If RBBB is discovered, a thorough cardiac evaluation including echocardiography may be warranted to rule out structural heart disease, as recommended by the 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1. No medications specifically treat RBBB itself; management focuses on addressing any underlying conditions. Patients with RBBB should inform healthcare providers about this finding before procedures, as it affects ECG interpretation. RBBB occurs because damage or dysfunction prevents electrical signals from traveling through the right bundle branch, forcing impulses to spread through the right ventricle via slower cell-to-cell conduction, resulting in the characteristic ECG pattern.
Some key points to consider in the management of RBBB include:
- The prevalence of bundle branch block increases with age, and is estimated at 1% of the population aged 17% at age 80 years, as noted in the guidelines for cardiac pacing and cardiac resynchronization therapy by the European Society of Cardiology 1.
- Syncope is usually seen in patients with bundle branch blocks who often have other cardiac diseases, mainly coronary artery disease and hypertensive heart disease, which explains their higher mortality rate.
- In patients with neuromuscular disease and any degree of fascicular block, with or without symptoms, cardiac pacing may have a place, in view of the unpredictable progression of AV conduction disease, as suggested by the European Heart Journal 1.
- The PR and HV intervals have been identified as possible predictors of third-degree AV block and sudden death, although the correlation between these intervals and the risk of sudden death is not well established, as discussed in the ACC/aha/hrs 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.
In summary, the management of RBBB should focus on addressing any underlying conditions, and patients with RBBB should be thoroughly evaluated to rule out structural heart disease. The decision to proceed with cardiac pacing or other interventions should be made on a case-by-case basis, taking into account the individual patient's risk factors and clinical presentation, as recommended by the 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.
From the Research
Definition and Causes of Right Bundle Branch Block
- Right bundle branch block (RBBB) is a condition where the normal electrical activity in the His-Purkinje system is interrupted, resulting in a characteristic appearance on the electrocardiogram (ECG) 2.
- The right bundle branch (RBB) is susceptible to traumatic block caused by "bumping" during right-heart catheterization, leading to catheter-induced RBB block (CI-RBBB) 3.
Diagnosis and Classification of RBBB
- Echocardiography can be used to study RBBB and differentiate the site of the block within the right bundle 4.
- RBBB can be classified into four groups: proximal block, peripheral block, diffuse block, and non-specific block, depending on the difference in mitral to tricuspid valve closure and tricuspid valve closure to the maximum opening of the pulmonary valve 4.
- The surface electrocardiogram can predict the risk of heart block during right heart catheterization in patients with preexisting left bundle branch block 5.
Clinical Implications of RBBB
- RBBB can provide valuable diagnostic information in various conditions, but it is often overlooked by cardiac electrophysiologists 3.
- The presence of RBBB in coronary artery disease implies more severe and extensive left ventricular myocardial damage as well as more severe CAD 6.
- RBBB is generally regarded as benign, but it can lead to diagnostic difficulties, pitfalls, or undesired consequences in certain situations 3, 2.