Causes of Right Bundle Branch Block
Right bundle branch block results from interruption of conduction through the right bundle branch, with etiologies spanning structural heart disease, degenerative processes, congenital conditions, infectious/inflammatory causes, and iatrogenic trauma. 1
Pathophysiologic Categories
The American College of Cardiology classifies RBBB causes as developmental, hereditary/genetic, metabolic, infectious, inflammatory, infiltrative, traumatic, ischemic, malignant, or degenerative in nature. 1
Structural and Ischemic Heart Disease
- Ischemic heart disease, particularly anterior myocardial infarction with persistent intraventricular conduction disturbances, represents a major cause and carries an unfavorable prognosis. 1
- Hypertensive heart disease is a recognized structural cause of RBBB. 1
- Cardiomyopathies of various types can produce RBBB, occurring more commonly in patients with preexisting cardiovascular disease. 1, 2
- In acute coronary syndrome, RBBB on admission is associated with older age, worse Killip class, and higher GRACE risk scores. 2
Degenerative and Infiltrative Processes
- Primary degenerative lesions of specialized conducting tissue occur as an isolated phenomenon, particularly in older individuals. 1, 3
- Sarcoidosis infiltrates the conduction system and can cause RBBB. 1, 3
- Cardiac tumors represent an infiltrative cause of RBBB. 1, 3
Infectious and Inflammatory Etiologies
- Myocarditis causes RBBB through inflammatory damage to the conduction system. 1, 3
- Chagas' disease is a specific infectious cause of RBBB. 1, 3
Congenital and Genetic Conditions
- Congenital heart disease, particularly atrial septal defects (especially ostium secundum type), commonly presents with RBBB. 1
- Ebstein's anomaly of the tricuspid valve displays prolonged PR interval and wide RBBB. 1
- Lenegre disease (progressive cardiac conduction disease) is an autosomal dominant condition linked to SCN5A gene mutations, presenting with various conduction defects including RBBB in young individuals. 1
- Congenital isolated complete RBBB is very rare in neonates. 1
- Arrhythmogenic right ventricular cardiomyopathy can present with RBBB pattern and requires specialized evaluation when accompanied by family history of sudden death or ventricular arrhythmias. 1
Iatrogenic and Traumatic Causes
- Catheter-induced RBBB occurs during right-heart catheterization, electrophysiological studies, and catheter ablation procedures due to the endocardial course of the right bundle branch making it susceptible to traumatic block from catheter "bumping." 4
- This catheter-induced RBBB is typically transient but may persist for the entire procedure duration. 4
Acute Conditions
- Massive pulmonary embolism with main pulmonary trunk obstruction causes newly emerged RBBB in 80% of cases, making it a significant marker for trunk embolism. 5
- Acute right ventricular overload from pulmonary embolism produces RBBB through hemodynamic stress. 5
Critical Clinical Pitfalls
- Always evaluate for structural heart disease with transthoracic echocardiography in newly detected RBBB cases, particularly when associated with other conduction abnormalities. 1
- Isolated RBBB rarely causes symptoms on its own, but its presence may be a marker for underlying structural heart disease. 1
- Bifascicular block (RBBB with left anterior or posterior hemiblock) carries increased risk of progression to complete AV block. 1, 3
- RBBB with ST-elevation in V1-V3 represents Brugada pattern and requires immediate specialized evaluation due to sudden cardiac death risk. 1
- In athletes, complete RBBB is uncommon (<2%) and warrants thorough investigation despite potentially representing idiopathic, clinically benign conduction delay. 1, 3
- Assess for syncope, presyncope, dizziness, fatigue, or exercise intolerance in patients with RBBB, as these symptoms suggest arrhythmic etiology requiring urgent evaluation. 1
- Family history of sudden cardiac death warrants genetic evaluation. 1
- Avoid catheter-induced RBBB in patients with baseline complete left bundle branch block, as this creates complete heart block risk. 4