From the Guidelines
Right bundle branch block (RBBB) on an ECG is diagnosed when an individual meets specific criteria, including an rsr, rsR, or rSR pattern in leads V1 or V2, an S wave of greater duration than the R wave or greater than 40 ms in leads I and V6, and a normal R peak time in leads V5 and V6 but greater than 50 ms in lead V1, as outlined in the 2009 AHA/ACCF/HRS recommendations 1.
Diagnosis of RBBB
To diagnose RBBB, the following criteria should be present:
- An rsr, rsR, or rSR pattern in leads V1 or V2, with the R or r deflection usually wider than the initial R wave
- An S wave of greater duration than the R wave or greater than 40 ms in leads I and V6 in adults
- A normal R peak time in leads V5 and V6 but greater than 50 ms in lead V1
Clinical Significance of RBBB
RBBB can occur in healthy individuals without clinical significance, but it may also indicate underlying heart disease such as coronary artery disease, cardiomyopathy, or congenital heart defects 1. The presence of RBBB alone typically doesn't require specific treatment, but the underlying cause should be investigated, especially if newly discovered.
Investigation and Management
Patients with RBBB or intraventricular conduction delay on ECG have an increased risk of left ventricular systolic dysfunction compared with those with completely normal ECGs 1. Echocardiography can identify various structural cardiac abnormalities underlying conduction disturbance, including cardiomyopathy, valvular heart disease, congenital anomalies, tumors, infections, infiltrative processes, immunologically mediated conditions, and diseases of the great vessels and pericardium. The diagnosis and management of RBBB should prioritize the identification and treatment of underlying cardiac conditions, rather than the RBBB itself, to improve morbidity, mortality, and quality of life outcomes 1.
From the Research
Definition and Electrocardiographic Features
- Right bundle branch block (RBBB) is characterized by a prolongation of the QRS complex > 0.12 s, RR' or rR' or Rr' appearances in V1, and widened S waves in the leads exploring the left ventricle (SI, aVL, V5, and V6) 2.
- A delay in the appearance of the intrinsic deflection > 0.08 s may also be observed in the right precordial leads, and negative T waves with ST depression may be seen in V1 and sometimes in V2 2.
Differential Diagnosis
- The principal differential ECG diagnosis is the Brugada syndrome, a familial arrhythmogenic autosomal dominant cardiomyopathy of variable penetration 2.
- RBBB with a QR pattern in V1 on the electrocardiogram (ECG) has a high positive predictive value for diagnosing cardiac arrest caused by high-risk pulmonary embolism 3.
Prognosis and Hemodynamic Consequences
- RBBB only seems to 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 good, but it may be poor in other cases, particularly coronary artery disease 2, 4, 5.
- RBBB is not a predictor of coronary artery disease, and its presence does not imply more severe and extensive left ventricular myocardial damage or more severe CAD 4, 5.
Association with Other Cardiac Conditions
- Bifascicular block (RBBB with left anterior hemiblock or left posterior hemiblock) can complicate acute myocardial infarction and is often associated with a poor prognosis and the presence of heart failure 6.
- Left anterior hemiblock pattern was also observed during angina pectoris occurring at rest or induced by exercise or atrial pacing, and is likely to be due to ischemia in the anterolateral wall related to a lesion of the main trunk or the proximal left anterior descending coronary artery 6.