Findings and clinical mimics of common limb-lead changes:
Right arm-Left arm:
- Q wave I, aVL
- Inverted p-wave I, II, II, aVF
- Mimics: old lateral infarct, non-sinus atrial activity, dextrocardia (limb lead reversal will still have normal R-wave progression, dextrocardia will not)
Right arm- Left leg:
- Q wave II, III, aVF
- Inverted p-wave II, III, aVF
- Mimics: old inferior infarct, non-sinus atrial activity
Right arm- Right leg:
- Diffuse low voltage in limb leads (esp. lead II)
- Mimics: any condition causing low voltage (limb-lead reversal will have normal precordial voltages)
Other limb lead reversals causing only minor changes with no real clinical mimics include Left arm- Left leg, Left arm- Right leg and leg-leg reversals. Precordial lead changes will interfere mostly with R-wave progression.
More from an old but concise review here.