Reflection on the average direction of ventricular depolarisation during ventricular contractions – Provides indication of the heart’s direction and position of the electrical activities.

  • ‘Axis’ refers to electrical depolarisation direction (in degrees°)
  • Normal electrical pathway would be leftward then downward


Method 1: ECG Leads
  • If aVF is unavailable – Lead II can be used but with extreme caution.
 Normal AxisRight Axis Deviation (RAD)Left Axis Deviation (LAD)Extreme Axis Deviation
Axis Angle 0 to +90° +90 to 180°0 to -90°-90 to 180°
Method 2: Hexaxial (Perpendicular) Reference System
  1. Look at the limb leads – Find smallest OR most equiphasic complex
  2. Using the degrees – Find this complex on the reference axis
  3. Trace to the centre then find perpendicular lead (right angle)
  4. Follow this lead back out to the axis quadrant


Types of Devations
Normal Deviation:
  • Normal electrical activity is leading towards Lead I (most positive) & aVF hence the positive leads. aVR is in opposite direction of the impulse therefore is negative
Left Axis Deviation (LAD):
  • Depolarisation to the left side usually caused by conduction abnormalities.
Right Axis Deviation (RAD):
  • Depolarisation to the right side may be due to extra tissue mass (stronger signal) – May be normal in tall individuals.
Extreme Axis Deviation (EAD):
  • Rare event usually from electrode misplacement – Can be due to ventricular tachycardia (if rhythm is tachycardia with wide QRS complex).
Axis Deviations Causes
No Axis DeviationLeft Axis DeviationRight Axis Deviation
  • No conditions
  • Healthy heart
  • Inferior AMI
  • Left Anterior Hemiblock
  • LBBB
  • Wolf Parkinson White Syndrome
  • Obesity
  • Pregnancy
  • Pacemaker (or paced rhythm)
  • Pulmonary Hypertension
  • Pulmonary Embolism
  • Dextrocardia
  • Anterior / Lateral AMI
  • Valvular Lesions
  • Right Ventricle Hypertrophy
  • COPD


College of Pre-Hospital Care. (2015). 12-Lead ECG Analysis: Self-Directed Learning Package. Version 3. St John Ambulance Ltd.  

Curtis, K., & Ramsden, C. (2016). Emergency and trauma care for Nurses and Paramedics (2nd ed.). Elsevier Australia.

DeLaune, S. C., Ladner, P. K., McTier, L., Tollefson, J., & Lawrence, J. (2016). Australian and New Zealand fundamentals of nursing (1st ed.). Cengage Learning Australia Pty Limited.

ECG & ECHO Learning. (2020). Clinical ECG Interpretation. https://ecgwaves.com/topic/ecg-normal-p-wave-qrs-complex-st-segment-t-wave-j-point/

Life in the Fast Lane. (2020). ECG Library. https://litfl.com/ecg-library/

St John WA Ltd. (2017). Electrocardiography (ECG). Clinical Resources. https://clinical.stjohnwa.com.au/clinical-skills/assessment/vital-signs/electrocardiography-(ecg)

WikiEM. 2020. The Global Emergency Medicine Wiki. https://www.wikem.org


Page contributors:

60825Thanh Bui, AP60825
Event Medic, Emergency Medical Technician &
Volunteer Development Officer



Andrew Moffat, AP16790
Volunteer Training Manager & Volunteer Development Officer

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