The initial portion of the QRS complex, with the Q waves in leads II, III and aVF, is directed superiorly (i.e. away from the inferior leads) with an axis of -60 degrees (vector #1). The middle portion of the QRS complex (vector #2) is directed to the left and inferiorly with an axis of about +30 degrees. The final portion of the QRS complex, with the S waves in lead I and aVL and the R waves in leads III and aVF, is directed inferiorly and slightly to the right (vector #3).