Which axis represents the overall direction of ventricular depolarization?

Which axis represents the overall direction of ventricular depolarization?

• A. Mean QRS axis
• B. P wave axis
• C. T axis
• D. QRS axis

Answer: (A)

The overall direction of ventricular depolarization is captured by the mean QRS axis. This axis reflects the net direction of the ventricular depolarization vector during the QRS complex, essentially the average orientation of that depolarization across the leads. The P wave axis corresponds to atrial depolarization, not the ventricles. The T axis reflects the direction of ventricular repolarization, not depolarization. So the axis that best represents the ventricular depolarization direction is the mean QRS axis.