Step 7c: Inspect QRS complexes for bundle branch block or fascicular block

In the setting of RBBB, the initial part of the ECG is unchanged because septal depolarization and depolarization of the left ventricle are unaffected. However, the right ventricle depolarizes in a delayed and slow fashion. This results in a widening of the terminal part of the QRS complex and orientation of the axis of the terminal part of the QRS complex to the right.