A 34 y/o female presents to the ED complaining of palpitations.
The EKG is below.
What finding does this EKG demonstrate?
What is the next step?
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:
inverted P-QRS-T waves in lead I
upright P-QRS-T in lead aVR (as opposed to the expected inversion of these waves in a normal EKG)
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.)