Limb Lead Reversal: Preliminary Findings

Back in January, Tom over at the EMS 12-Lead blog had an interesting case entitled "Bait and Switch" in which the diagnosis of a STEMI was potentially masked due to incorrect limb lead placement. Interestingly, the limb lead placement was not one of classic LA/RA reversal, but rather a "rotation" of the limb leads. In this instance, the cardiac monitor did not detect the incorrect limb lead positioning. Over the last few weeks I have set out to collect 12-Lead ECGs acquired from each of the 24 possible limb lead positions and to catalog the characteristics of each.

All of the ECGs I have acquired are on LifePak 12 monitors using the GE Marquette 12SL algorithm. Currently, only classic limb lead reversal has produced the, "*** Suspect arm lead reversal, interpretation assumes no reversal," message. However, I still have 12 combinations of lead placements to complete.

Here are 3 ECG's acquired from a healthy male subject without any known cardiac abnormality or history (i.e. me).

Normal ECG **Unconfirmed**; Normal Sinus Rhythm

Abnormal ECG **Unconfirmed**; *** Suspect arm lead reversal, interpretation assumes no reversal; Normal sinus rhythm; Right axis deviation; Nonspecific ST abnormality.

Abnormal ECG **Unconfirmed**; Unusual P-axis, possible ectopic atrial rhythm; Left axis deviation; ST & T wave abnormality, consider inferior ischemia