Figure 1: The drawing method for determination of the heart axis using the QRS complex. (a) Plot the net deflection of QRS complex
(mean QRS) for both leads I and aVF along each lead; (b) Run perpendicular lines from each of the plotted points; (c) Z point represents
the apex of the mean QRS axis; (d) Draw a vector between O point and Z point. The angle between lead I and OZ vector is the angle of the
heartís electrical axis.
Keywords: QRS complex