For example, the normal QRS complex in lead V1 does not contain a Q wave — only a R wave and S wave — but the combination of the R wave and S wave is still referred to as the QRS complex for ...

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 ...