Right Bundle Branch Block
Objectives
To be able to explain the pathophysiology behind right bundle branch block
Click to CompleteTo be able to distinguish the ECG changes present in RBBB and demonstrate this
understanding on example ECGs
Click to CompleteBe able to describe the causes of RBBB
Click to CompleteTo apply the skills covered to complete the RBBB quiz
Click to CompleteDefinition
In RBBB, activation of the right ventricle is delayed as depolarisation
has to spread across the septum from the left ventricle
The left ventricle is activated normally, meaning that the early part of the
QRS complex is unchanged
The delayed right ventricular activation produces a secondary
R wave (R’) in the right precordial leads (V1-3) and a wide, slurred S wave in the
lateral leads
Delayed activation of the right ventricle also gives rise to secondary
repolarization abnormalities, with ST depression and T wave inversion
in the right precordial leads
In isolated RBBB the cardiac axis is unchanged, as left ventricular activation
proceeds normally via the left bundle branch
ECG features of RBBB
Diagnostic Criteria
- Broad QRS > 120 ms
- RSR’ pattern in V1-3 (‘M-shaped’ QRS complex)
- Wide, slurred S wave in the lateral leads (I, aVL, V5-6)
Associated Features
- ST depression and T wave inversion in the right precordial leads (V1-3)
ECG features of RBBB
Example ECG
Can you identify on this ECG the specific signs needed
to diagnose Right Bundle Branch Block?
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Answers!
Broad QRS > 120 ms - Leads V1,V2,V3
RSR’ pattern in - V1
Wide, slurred S wave - Lead I and aVL
ST depression and T wave inversion - Leads V1,V2,V3,V4
Causes of RBBB
- Right ventricular hypertrophy / cor pulmonale
- Pulmonary embolus
- Ischaemic heart disease
- Rheumatic heart disease
- Myocarditis or cardiomyopathy
- Degenerative disease of the conduction system
- Congenital heart disease (e.g. atrial septal defect)
RBBB Quiz
Click to Test your knowledge!
References
1. Right Bundle Branch Block (RBBB). LITFL: Life in the Fast Lane Medical Blog.
2011 [cited 2016 Apr 24]. Available from:
http://lifeinthefastlane.com/ecg-library/basics/right-bundle-branch-block
2. RBBB is it a side effect of operation - EKG Machines Blog
Articles [Internet]. [cited 2016 Apr 24]. Available from:
http://www.ekgmachines.org/article/7128100413/rbbb-is-it-a-side-effect-of-operation-or-/