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—the average orientation of the QRS vectors across the heart. Think of the ventricles depolarizing as a vector moving through the myocardium; the mean QRS axis is that net direction, not tied to any single lead but to the sum of all QRS activity. The P wave axis, by contrast, reflects atrial depolarization, while the T axis reflects ventricular repolarization. So the axis that best represents how the ventricles depolarize as a whole is the mean QRS axis (often simply called the QRS axis).

The overall direction of ventricular depolarization is captured by the mean QRS axis—the average orientation of the QRS vectors across the heart. Think of the ventricles depolarizing as a vector moving through the myocardium; the mean QRS axis is that net direction, not tied to any single lead but to the sum of all QRS activity. The P wave axis, by contrast, reflects atrial depolarization, while the T axis reflects ventricular repolarization. So the axis that best represents how the ventricles depolarize as a whole is the mean QRS axis (often simply called the QRS axis).