Question

While preparing your participant for an EKG, you accidentally switched the RA and LA wire leads.

a. what would the waveforms look like in leads I, II, III, aVF, aVL, and aVR? Illustrate and label the wave forms to help your explanation. b. Why will they look this way? Incorporate electrode polarity and the concept of mean QRS vector (direction) in your answer. Suggestion: draw the leads in their correct and incorrect orientation with the polarity labeled in both as well as the mean QRS vector.

Answer 1

Switch of LA and RA wire Leads:

a. Lead I - Lead I become inverted.

Lead II replaced by Lead III

Lead III replaced by Lead II

AVF remains unchanged.

AVL is switched to the place of AVR

AVR is switched to the place of AVL.

Waveforms in the reversal of LA and RA   

AVR AUL INUERTED AV AVR AUF UNCHANGED

b. Reversal of LA and RA leads to right axis deviation and resembles the dextrocardia. The lead reversal can be easily identified by inverted P and QRS complex in the Lead I and shows positive QRS in V₃ - V6. In between V3 - V6 The QRS looks smaller.