ECG: Axis Deviation

Question 1

What are some causes of left axis deviation? (LAD)

Answer 1

1. Left anterior hemiblock
2. Left bundle branch block
3. Wolff-Parkinson-White syndrome* - right-sided accessory pathway
4. Hyperkalaemia
5. Congenital: ostium primum ASD, tricuspid atresia
6. Minor LAD in obese people

Question 2

What are some causes of right axis deviation? (RAD)

Answer 2

1. Right ventricular hypertrophy
2. Left posterior hemiblock
3. Chronic lung disease → cor pulmonale
4. Pulmonary embolism
5. Ostium secundum ASD
6. Wolff-Parkinson-White syndrome* - left-sided accessory pathway (But most of the time it is a left axis deviation)
7. Normal in infant < 1 years old
8. Minor RAD in tall people