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ECG - Right Bundle Branch Block RBBB
Related Subjects: |ECG Basics |ECG Axis |ECG Analysis |ECG LAD |ECG RAD |ECG Low voltage |ECG Pathological Q waves |ECG ST/T wave changes |ECG LBBB |ECG RBBB |ECG short PR |ECG Heart Block |ECG Asystole and P wave asystole |ECG QRS complex |ECG ST segment |ECG: QT interval |ECG: LVH |ECG RVH |ECG: Bundle branch blocks |ECG Dominant R wave in V1 |ECG Acute Coronary Syndrome |ECG Crib sheets |Right Ventricular ST Elevation MI (RVMI)
🧠 Teaching point: New RBBB is not always pathological, and its frequency increases with age. Always interpret in the clinical context.
📖 About
- ⚡ Right Bundle Branch Block (RBBB) is a conduction delay in the right bundle branch.
- 🧭 It may be a normal variant, especially in older adults, but can also reflect right heart pathology.
📊 ECG Appearance
- ⏱️ QRS duration >0.12 s (≥3 small squares).
- 📈 RsR’ “M” pattern in V1–V2 (secondary R wave).
- 📉 Wide, slurred S wave (“W”) in leads I, V5, V6.
- 🧠 Aide memoire: MO(RR)OW (M in V1, W in V6 for RBBB).
🧬 Aetiology (mechanism)
- ⬅️ Left ventricle depolarises first (via left bundle).
- ➡️ Right ventricle depolarises later (via slow cell-to-cell conduction).
⚠️ Causes of RBBB
- ✅ Normal variant (especially with age).
- 🫁 Acute pulmonary embolism, RV infarction.
- 🌬️ Chronic lung disease (COPD, cor pulmonale), RV hypertrophy.
- 🫀 Atrial Septal Defect (esp. secundum ASD), congenital heart disease.
- 🔥 Myocarditis or idiopathic conduction disease.
Typical ECG: wide QRS, secondary R wave in V1, delayed S waves in leads I, aVL, V5–V6.
Wide QRS, secondary R wave in V1/V2, broad S waves in lateral leads.
Classic RBBB with “M” in V1 and “W” in V6.
🔊 Clinical Features
- 👂 Widened splitting of the 2nd heart sound (delayed closure of pulmonary valve).
- 🫀 May be associated with RV strain in pulmonary embolism or pulmonary hypertension.
🛠️ Management
- ✅ Often benign, especially in older adults with no structural disease.
- ⚠️ If new or symptomatic ➝ assess for PE, MI, myocarditis, or structural heart disease (ECHO, imaging).
- 🔍 Persistent RBBB may warrant cardiology review.
💡 Teaching Pearls
✔️ LBBB is almost always pathological, but RBBB can be benign. ✔️ In suspected PE, the presence of RBBB + right axis deviation + S1Q3T3 pattern suggests acute RV strain. ✔️ RBBB does not obscure ST elevation diagnosis as much as LBBB does.
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