For example, the normal QRS complex in lead V1 does not contain a ... and the QRS duration is widened. A widened QRS duration occurs in the setting of a right bundle branch block, left bundle ...

If the QRS complex is widened and downwardly deflected in lead V1, a left bundle branch block is present. If the QRS complex is widened and upwardly deflected in lead V1, a right bundle branch ...