What term describes a shift of the mean QRS axis beyond normal boundaries?

• A. Axis Deviation
• B. Axis Inversion
• C. Axis Rotation
• D. Axis Reversal

Answer: (A)

Axis deviation describes a mean QRS axis that has shifted beyond the normal range. The heart’s electrical axis represents the overall direction of ventricular depolarization, and in a typical adult the QRS axis lies roughly from -30° to +90°. When the axis moves outside that window, it’s called axis deviation, with left axis deviation or right axis deviation as the common patterns. The other terms don’t describe this phenomenon in standard ECG language: inversion, rotation, or reversal imply different concepts and aren’t the usual descriptors for a mean QRS axis shifting beyond normal boundaries.