How To determine the Mean Electrical Axis in ECG?????? Simple isn't it!!!

Electrical axis...

• Mean direction of the QRS complex in the frontal plane towards which the QRS complex is predominately

 pointed.

• Since by definition it is calculated in frontal plane only, therefore MEAN ELECTRICAL AXIS is calculated

 only from the frontal or Limb leads.
Mean QRS Axis Calculation

• the mean QRS axis is oriented at right angles (90°) to any lead showing a bi-phasic complex
• the mean QRS axis points midway between any two leads that show tall R waves of equal height

This program demonstrates changes in the frontal surface leads with shifts in the cardiac axis .

                                                                       

                                                                  (OR)

Calculation of frontal plane axis : If the QRS complex is positive in leads I and II, it falls between -30 and 90°
 and is normal, as indicated by the yellow area. If the QRS complex is negative in I and positive in aVF, 
there is right axis deviation. If the QRS complex is positive in I and negative in II, there is left axis deviation.
 If the QRS complex is negative in I and aVF, there is extreme axis deviation.