Right bundle branch block (RBBB)

In summary:

• Right bundle branch block patterns with a normal duration of QRS complex are quite common in healthy people. There is no evidence to suggest established RBBB carries other than a normal prognosis (1)
  
  
• Right bundle branch block may indicate pathology in the right side of the heart e.g. right ventricular strain (especially due to pulmonary embolism). Right bundle branch block may occur in other pathologies e.g. atrial septal defect (especially ostium secundum), myocardial ischaemia.

More detailed information concerning RBBB is provided below:

• incomplete RBBB is a common finding and may be considered a normal variant (2)
  • incomplete RBBB has also been associated with right ventricular hypertrophy (RVH) and right ventricular dilatation
    • someone with incomplete RBBB have an increased risk of developing complete RBBB compared to someone developing complete RBBB with no history of incomplete RBBB (approximately 7 x the risk)
      • no increased risk of cardiovascular death was seen when patients with incomplete RBBB were followed for a 20 year period (3)
      • study evidence showed that 95% did not develop complete RBBB in 11 years follow-up (3)
• complete RBBB offten occurs in people without clinical evidence of structural heart disease
  • RBBB in younger individuals generally is not indicative of serious underlying heart disease (4)
    • however complete RBBB may associated with underlying pathology:
      • Framingham study data suggest that the development of RBBB after having had a normal pattern is strongly suggestive of organic heart disease (4)
        • RBBB is seen in acute myocardial infarction in 3-7% of cases (5)
      • RBBB occurs in Brugada syndrome (6,7)
        • Brugada syndrome is characterized by right bundle branch block and coved-type ST segment elevation in the right precordial leads on 12-lead ECG and sudden death following ventricular fibrillation
        • mutation of the cardiac sodium channel gene SCN5A has been identified in some clinical cases, but most of the reported cases have been adult male patients despite the condition's autosomal dominant inheritance
        • the autonomic nervous system is considered to play an important role in modulation of this ECG abnormality
        • a study has found that subjects with the Brugada-type ECG have slender builds (7). The authors suggest that this may provide a clue to the basic mechanisms of the Brugada-type ECG with a focus on this association
      • RBBB has been associated with pulmonary embolism
      • other pathologies associated with RBBB include:
        • hypertension
        • atrial septal defect
        • rheumatic heart disease
        • cor pulmonale
        • cardiomyopathy
        • myocarditis
        • Chagas' disease
        • degenerative disease of the cardiac skeleton
        • secondary to cardiac procedures:
          • right heart catherization may induce transient RBBB
          • transient or persistent RBBB may occur after coronary artery bypass procedures or after heart transplant
        • tricyclic antidepressant overdose may be associated with development of a RBBB

Click here for an example ECG of RBBB

Reference:

1. Rowlands DJ.Left and right bundle branch block, left anterior and left posterior hemiblock. Eur Heart J. 1984 Mar;5 Suppl A:99-105.
2. Harrigan RA et al. Electrocardiographic manifestations: bundle branch blocks and fascicular blocks. The Journal of Emergency Medicine 2003;25(1):67-77.
3. Liao Y et al. Characteristics and prognosis of incomplete right bundle branch block: an epidemiologic study. J Am Coll Cardiol 1986;7: 492-499.
4. Schneider JF et al. Newly acquired right bundle branch block: the Framingham study. Ann Intern Med 1980;92: 37-44.
5. Scheidt S, Killip T. Bundle branch block complicating acute myocardial infarction. JAMA 1972;222: 919-924.
6. Brugada P, Brugada J.Right bundle branch block, persistent ST elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol 1992;20:1391-1396
7. Matsuo et al. Clinical Characteristics of Subjects with the Brugada-Type Electrocardiogram. Journal of Cardiovascular Electrophysiology 2004;15 (6): 653-657.