Lead reversal: Left arm/right arm

LA/RA reversal

With reversal of the LA and RA electrodes, Einthoven’s triangle flips 180 degrees horizontally around an axis formed by lead aVF.

ECG Lead reversal LA-RA diagram
ECG LA-RA Lead reversal

This has the following effects on the ECG:

  • Lead I becomes inverted.
  • Leads II and III switch places.
  • Leads aVL and aVR switch places.
  • Lead aVF remains unchanged.
ECG Leads LA RA Reversal
LA/RA reversal
ECG Leads Baseline ECG
Baseline ECG

Quick guide to spotting LA/RA reversal

  • Lead I is completely inverted (P wave, QRS complex and T wave).
  • Lead aVR often becomes positive.
  • There may be marked right axis deviation.

LA/RA reversal may simulate dextrocardia. However, in contrast to dextrocardia there is normal R wave progression in the precordial leads.

la-Lead-reversal
LA/RA reversal simulating dextrocardia
Lead-reversal-reversed
LA/RA reversal reversed

Related Topics


LITFL Further Reading


Advanced Reading


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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 |

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