The portion of the ventricle that is infarcted becomes unexcitable and does not participate in the sequence of depolarization. Rather, it acts as a window through which electrodes placed over that area are able to “see” the electrical activity generated simultaneously but in the opposite direction (i.e. going away from the electrodes overlying the infarcted region). Because the infarcted tissue is distal to the point of coronary occlusion, and because the spread of activation is from apex to base, the infarcted region is most often depolarized within the early portion of the QRS complex. The presence of an abnormal Q wave indicates that the spread of excitation during the early portion of the QRS complex is directed away from the leads recording the Q waves.