EKG of the Week 2018 12-23

A 34 y/o female presents to the ED complaining of palpitations.

The EKG is below.

2018 12-23.JPG
  1. What finding does this EKG demonstrate?

  2. What is the next step?

ANSWER:

The EKG demonstrates limb lead reversal of the right arm and left arm.

Repeat the EKG with appropriate lead placement.

 

The EKG appears to demonstrate T wave inversions in leads II, III and aVF and can be mistaken for inferior wall ischemia. However, a closer look at the EKG reveals that in lead I the P wave is inverted, the QRS complex is predominantly negative, and the T wave is inverted. In lead aVR, the P wave is upright, the QRS complex is predominantly positive, and the T wave is upright. This is the opposite of what you expect to see in a normal EKG. This clues you in that the right and left arm leads have been reversed. With limb lead reversal, T wave inversions may appear that are not really signs of ischemia.

The findings on EKG in reversal of right and left arm leads are:

  1. inverted P-QRS-T waves in lead I

  2. upright P-QRS-T in lead aVR (as opposed to the expected inversion of these waves in a normal EKG)

  3. QRS vector in lead I does not match that of lead V6

 

Inversion of the P-QRS-T complex in lead I can also occur with dextrocardia. However, with dextrocardia, there will be a lack of normal precordial R-wave progression from leads V1–V6. In reversal of the arm electrodes, the precordial leads will not be affected so R wave progression should be normal.

Reversal of the right leg and left leg leads usually causes no change on the EKG because the right leg lead is only a ground and does not record any electrical activity.

(Harrigan et al. Electrocardiographic Electrode Misplacement, Misconnection, and Artifact. J Emerg Med. 2012;43(6):1038-1044.)