Brandon Fainstad, MD
Objectives
- Identify the rSR' morphology in lead V1 that is characteristic of a right bundle branch block (RBBB).
Teaching Instructions
Plan to spend 5 minutes familiarizing yourself ECG. Have the image pulled up on the presenting screen or monitor. Ask for a full read of the ECG. If the learner has not done so already, ask them to commit to a rhythm
Diagnosis: Sinus rhythm with right bundle branch block and inferior (II, III and aVF) q waves. Sinus rhythm with right bundle branch block and inferior (II, III and aVF) q waves. RBBB likely due to prior infract from RCA occlusion)
Teaching: RBBB morphology is defined by an r-S-R’ in the septal precordial leads (V1-2) and a “slurred” S wave in the lateral leads (I, aVL, V5 and V6). A RBBB is occasionally a benign normal variant but the inferior Q waves in this case give a consistent story of prior inferior infarct causing disruption in the right purkinje bundle, leading to the RBBB morphology.
Advance to subsequent slides for zoomed-in image and a comparison between left and right bundle branch blocks.
ECG
Take Home Point
- RBBB morphology is defined by an r-S-R’ in the septal precordial leads (V1-2) and a “slurred” S wave in the lateral leads (I, aVL, V5 and V6).
- A RBBB is occasionally a benign normal variant but associated pathology (e.g., the inferior Q waves in this case) or a concerning clinical history for coronary artery disease should raise concerns for a pathologic RBBB.
References
Goldberger, A. L., Shvilkin, A., Goldberger, Z. D. (2017). Clinical Electrocardiography: A Simplified Approach E-Book. United States: Elsevier Health Sciences.
