The electrical forces generated by the unopposed depolarization of the interventricular septum , i.e., that part of ventricular depolarization that is responsible for the initial 10-20 ms of the QRS complex, will be associated with a magnitude and direction that reflect its size and spatial orientation. The septum is depolarized from the left ventricular side to the right and the left ventricule is posterior as well as to the left of the right ventricle. As a result, the elctrical forces will be directed anteriorly and to the right.