Wednesday, 26 September 2018

ECG of the Week - 24th September 2018 - Interpretation

This ECG is from a 15 year old male who presented with episodes of symmetrical hands turning cold and blue (symmetrically) which lasted for a few hours before improving. No prior past medical history, no regular medications. Very fit and active.

Click to enlarge
  • 60 bpm
  • Regular
  • Atrial activity present but inverted P wave leads V2 & V5
  • Extreme
  • PR - Normal 
  • QRS - Normal
  • T wave inversion leads II, III, aVF, V1-2, V5
  • Abnormal R wave transition in precordial leads
    • Negative QRS leads V1-2
    • Positive QRS leads V3-4
    • Negative QRS leads V5-6
  • Complete lead inversion V2 & V5 (Negative P, negative QRS, negative T)


The combination of abnormal R wave transition, complete lead inversion leads V2 & V5 plus extreme axis should always alert us to the possibility of lead reversal.
This is clearly not a 'simple' reversal i.e. only 2 leads misplaced but far more complex. The odds of every lead being attached to a patient incorrectly is very small but the connection between the leads and the machine is much easier to misconnect especially when old and worn. This what happened in this case with the connecting terminal for all the leads was placed upside down into the ECG machine with resultant lead swaps as below.

Expected lead                   Actual lead
RL                                           RL
RA                                          V6
V1                                           V1
V2                                           RA
V3                                           V5
V4                                           V4
V5                                           LA
V6                                           V2
LA                                           V3

LL                                            LL

Once corrected the patients subsequent ECG was entirely normal !

References / Further Reading

Life in the Fast Lane

  • Lead reversal
  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.

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