ECG of the Week 30th March 2022 Answer

45 year old female with no prior history, presents with chest pain post Pfizer vaccine.

Describe and Interpret the ECG


Rate 72 bpm

Rhythm: normal sinus

Axis: Extreme axis –90

PR  140ms

QRS 80ms

QT 394ms (Bazett)


  • Inverted P-QRS-T in leads I/II
  • Inverted QRS-T in leads III and aVF
  • Upright P-QRS-T in aVR

The above ECG is typical for electrode misplacement, with its extreme axis and abnormal P-QRS-T deflection in the limb leads and normal R wave progression in the chest leads.

The above ECG is an example of right arm/left leg reversal which is typically characterised by:

  • P-QRS-T are inverted in all leads except aVL
  • Upright P-QRS-T in aVR

Electrode reversal should be suspected when

  • aVR is upright and another lead looks like aVR
  • axis is unexpectedly abnormal
  • inverted P waves in limb leads – I and II
  • Flattened leads I/II/III


Chan et al, ECG in Emergency Medicine and Acute Care, Elsevier Mosby, 2005