From the Guidelines
A right bundle branch block (RBBB) on an EKG is characterized by a widened QRS complex (≥120 ms) with an rsr', rsR', or rSR' pattern in leads V1 or V2, an S wave of greater duration than the R wave or >40 ms in leads I and V6, and a normal R peak time in leads V5 and V6 but >50 ms in lead V1, as defined by the 2019 ACC/AHA/HRS guideline 1.
Key Characteristics of RBBB
- Widened QRS complex (≥120 ms)
- rsr', rsR', or rSR' pattern in leads V1 or V2
- S wave of greater duration than the R wave or >40 ms in leads I and V6
- Normal R peak time in leads V5 and V6 but >50 ms in lead V1
Clinical Implications
RBBB can be a normal variant in healthy individuals or may indicate underlying heart disease such as coronary artery disease, cardiomyopathy, or congenital heart defects. Unlike left bundle branch block, isolated RBBB often doesn't require specific treatment unless there are associated symptoms or underlying cardiac conditions. The diagnosis of RBBB is based on the presence of these specific criteria, as outlined in the 2019 ACC/AHA/HRS guideline 1 and supported by earlier recommendations 1.
From the Research
Right Bundle Branch Block on EKG
- A right bundle branch block (RBBB) on an electrocardiogram (ECG) is characterized by a QR pattern in lead V1, which has a high positive predictive value for diagnosing cardiac arrest caused by high-risk pulmonary embolism 2.
- The appearance of RBBB in ECGs of patients with pulmonary embolism is a marker for obstruction of the main pulmonary trunk, with 80% of trunk embolism patients showing a newly emerged RBBB in their ECG 3.
- RBBB can also be associated with coronary artery disease (CAD), but it is not a predictor of CAD, with studies showing no significant association between the presence of RBBB and the magnitude of Gensini score 4.
- In patients with CAD, RBBB may imply more severe and extensive left ventricular myocardial damage, as well as more severe CAD, with higher end-diastolic left ventricular pressure and more severe and diffuse left ventricular wall asynergy 5.
ECG Characteristics
- RBBB on ECG is characterized by a wide QRS complex (>120 ms) with a terminal R wave in lead V1, and a deep S wave in lead V6 2, 3.
- The presence of a QR pattern in lead V1 is a significant sign of the probability of massive obstruction of the main pulmonary trunk 3.
- RBBB can also be associated with other ECG changes, such as ST-segment depression and T-wave inversion in leads V1-V4, and right axis deviation 2, 3.
Clinical Implications
- The presence of RBBB on ECG should prompt consideration of high-risk pulmonary embolism, particularly in patients with cardiac arrest or hemodynamic collapse 2.
- RBBB may also be associated with more severe CAD, and its presence should prompt further evaluation and management of CAD 5, 4.
- The appearance of RBBB in ECGs of patients with pulmonary embolism is a significant sign of the probability of massive obstruction of the main pulmonary trunk, and should prompt urgent thrombolytic therapy or other advanced treatments 2, 3.