Left Axis Deviation (LAD)

Left Axis Deviation LAD

Left Axis Deviation = QRS axis less than -30°.

  • Normal Axis = QRS axis between -30° and +90°
  • Right Axis Deviation = QRS axis greater than +90°
  • Extreme Axis Deviation = QRS axis between -90° and 180° (AKA “Northwest Axis”)

Hexaxial Reference System

Haxaxial ECG AXIS Reference

Hexaxial Reference System – relationship between QRS axis and frontal leads of the ECG.


How to recognise left axis deviation

Three Lead analysis
  • QRS is POSITIVE (dominant R wave) in Lead I
  • QRS is NEGATIVE (dominant S wave) in leads II, III and aVF
Lead-I-II-aVF-Hexaxial-Evaluation-LAD-Pathological

Example ECG of LAD

Left Anterior Fascicular Block (LAFB) Left axis LAD

Left Axis Deviation:

  • Leads I and aVL are positive; leads II and aVF are negative

Causes of LAD


Related Topics


LITFL Further Reading

Advanced Reading

ECG LIBRARY 700

ECG LIBRARY

Electrocardiogram

Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.