From the Guidelines
Right bundle branch block (RBBB) is characterized by a widened QRS complex on an ECG due to delayed electrical activation of the right ventricle, resulting in a QRS duration greater than 120 milliseconds, as defined in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Key Features of RBBB
- Delayed electrical activation of the right ventricle
- Widened QRS complex on ECG
- QRS duration greater than 120 milliseconds
- Characteristic ECG pattern shows an RSR' pattern in the right precordial leads (V1-V3) and wide S waves in the lateral leads (I, aVL, V5-V6)
Clinical Implications
- RBBB may occur in healthy individuals or indicate underlying cardiac disease such as coronary artery disease, cardiomyopathy, or congenital heart defects
- No specific treatment is needed for isolated RBBB, but evaluation for underlying heart disease may be warranted depending on clinical context, as recommended in the 2018 ACC/AHA/HRS guideline 1
Diagnosis and Evaluation
- ECG is the primary diagnostic tool for RBBB
- Evaluation for underlying heart disease may include additional tests such as echocardiography, stress testing, or cardiac catheterization, as indicated in the 2018 ACC/AHA/HRS guideline 1
Management
- No specific treatment is needed for isolated RBBB
- Evaluation and management of underlying heart disease may be necessary, as recommended in the 2018 ACC/AHA/HRS guideline 1 and the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: executive summary 1
From the Research
Right Bundle Branch Block and QRS Complex
- The QRS complex is prolonged in right bundle branch block (RBBB), with a duration of more than 0.12 seconds 2.
- The QRS complex in RBBB typically shows an RR' or rR' pattern in lead V1, with widened S waves in leads exploring the left ventricle (SI, aVL, V5, and V6) 2.
- A delay in the appearance of the intrinsic deflection of more than 0.08 seconds may be observed in the right precordial leads, and negative T waves with ST depression may be seen in V1 and sometimes in V2 2.
Effect of Right Bundle Branch Block on QRS Amplitudes
- RBBB is associated with an increase in initial QRS forces (RV1, RV2, and QV6) but significant decreases in mean mid-QRS amplitudes that reflect left ventricular depolarization (RaVL, SV1, SV3, RV5, and RV6) 3.
- All late QRS forces are increased with RBBB (R'V1, SV5, SI) 3.
- Combined voltages used for left ventricular hypertrophy (LVH) criteria are significantly reduced by RBBB, including Sokolow-Lyon voltage and Cornell voltage 3.
Clinical Significance of Right Bundle Branch Block
- RBBB may have hemodynamic consequences in cardiac failure with associated asynchrony of the left ventricle or in certain cases of right ventricular dilatation encountered in congenital heart disease 2.
- The prognosis of RBBB in the absence of underlying cardiac disease is generally good, but it may be poor in other cases, particularly coronary artery disease 2, 4, 5.
- RBBB is associated with increased cardiovascular morbidity and mortality, and its presence in patients with suspected acute coronary syndromes may indicate a need for further evaluation and potential acute invasive evaluation 5.