06/10/2025
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🚫 In Bundle Branch Block
One of the bundle branches (right or left) is blocked or delayed, so one ventricle contracts later than the other.
🔹 Types
1. Right Bundle Branch Block (RBBB):
• Block in the right branch.
• The right ventricle is activated late.
• ECG: “Rabbit ears” (R-S-R’) in V1–V2.
• Often benign or due to conditions like pulmonary embolism, ASD, or right heart strain.
2. Left Bundle Branch Block (LBBB):
• Block in the left branch.
• The left ventricle is activated late.
• ECG: Wide QRS, deep S in V1, broad R in V6.
• Often indicates heart disease (e.g., ischemia, cardiomyopathy, hypertension).
⚠️ Key ECG Feature
• QRS duration ≥ 120 ms (wide QRS complex).
❤️ Causes
• Myocardial infarction
• Cardiomyopathy
• Hypertension
• Pulmonary embolism (RBBB)
• Aging / fibrosis of conduction system
🩺 Symptoms
Usually none, but may cause:
• Dizziness or fainting (if severe conduction problem)
• Worsened heart failure symptoms (in LBBB)
💊 Treatment
• Treat underlying cause.
• Pacemaker may be needed if the block causes serious rhythm problems or heart failure.
