Right axis deviation on ECG is defined as QRS axis greater than what angle?

Right axis deviation on ECG is defined as QRS axis greater than what angle?

• A. Greater than +90 degrees
• B. Between -30 and +90 degrees
• C. Less than -90 degrees
• D. Exactly 0 degrees

Answer: (A)

Right axis deviation means the overall direction of ventricular depolarization in the frontal plane is shifted to the right. This is defined when the QRS axis exceeds +90 degrees. The normal frontal-plane QRS axis is about -30 to +90 degrees, so anything beyond +90 is considered rightward deviation. The range -30 to +90 is normal, an axis less than -90 would be extreme left axis deviation, and an axis of 0 degrees is still within normal limits. Recognizing this helps interpret why the axis has moved rightward on the ECG.

Right axis deviation means the overall direction of ventricular depolarization in the frontal plane is shifted to the right. This is defined when the QRS axis exceeds +90 degrees. The normal frontal-plane QRS axis is about -30 to +90 degrees, so anything beyond +90 is considered rightward deviation. The range -30 to +90 is normal, an axis less than -90 would be extreme left axis deviation, and an axis of 0 degrees is still within normal limits. Recognizing this helps interpret why the axis has moved rightward on the ECG.