ECG of the Week 30th March 2022 Answer

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

Describe and Interpret the ECG

Answer:

Rate 72 bpm

Rhythm: normal sinus

Axis: Extreme axis –90

PR  140ms

QRS 80ms

QT 394ms (Bazett)

Additional

  • 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

References:

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