Bundle branch block

Definition

Cessation of appropriate electrical conduction down either the left of right bundle branch.

Pathophysiology

• LBBB: aortic stenosis, dilated cardiomyopathy, MI, CAD.
• RBBB: atrial septal defect, PE, MI

ECG Changes

Think WiLLiaM and MaRRoW. See the text if that doesn't make sense.

If you're not sure about bundle branch block, think of WiLLiaM and MaRRoW

• LBBB: there is a W shape in V1 and an M shape in V6.
• RBBB: there is an M shape in V1 and a W shape in V6.