The power of social media leads to reversal

A reader (Christopher Watford) recently contacted the LITFL team with a query regarding a Visual Aid Question (VAQ) from the first sitting of the 2007 examination. So the team set about investigating the validity of the query using the power of social media…

For me, this scenario has been fascinating for a number of reasons

  • I have observed first hand the power of social media in medical education. The LITFL team were be able to readily and rapidly access a large number of eminent emergency physicians, cardiologists and electrophysiologists and receive timely and accurate responses.
  • This fellowship examination case involves an ECG that has been seen by countless examiners, examinees and registrars in training…yet it has taken 4 years before one astute reader has posted a comment that led us to review, interrogate and question the appropriateness of the scenario ECG
  • Is there fear and trepidation surrounding public comment? The fact is that I am sure others have made a similar observation when reviewing this question yet failed to alert us of the issues. Was this lack of feedback associated with emergency physicians being too time-poor, too indecisive or too catatonically apathetic to comment?
  • Finally I wonder if the abnormality was actually picked up by the candidates and examiners during the examination marking process but deemed too insignificant to warrant comment in the official examiners report…?

Anyway… Enough hyperbole —here is the VAQ question replicated in full from the first sitting of the fellowship written examinations form 2007 — can you spot the issue?


A 49 year old woman presents to your emergency department with central chest pain. His observations are:


a. Describe and interpret her ECG (50%)
b. Outline your disposition considerations (50%)

Official ACEM Response

  • Overall pass rate for this question was 32/55 (58.2%).
  • ECG showed widespread T wave inversion, concave up ST elevation and PR depression inviting in this clinical context a discussion re a number of differentials including pericarditis.
  • This was viewed as a difficult but relevant ECG which was satisfactorily interpreted by most candidates.
  • The discussion re echocardiography was generally superficial and was the major reason for poor scores.

The pertinent observer

I was looking at FACEM 2007.1 ECG quiz and it appears that the ECG has a limb lead mixup…I’m having trouble conceiving of pericarditis with the T-waves so deeply inverted in III/aVF.

I believe the following lead configuration may have been used (with the limb leads on the body): – RA: Green – LA: White – RL: Red – LL: Black

It would preserve P-waves in II and aVF and invert T’s in II/III/aVF. Leads I/aVR/aVL would remain relatively undisturbed. Does that seem feasible?

Christopher Watford – Paramedic

The Cardiologist

Sure looks like it could be LA/LL limb lead reversal. The large P wave and QRS voltage in I  and smaller QRS voltage in aVF makes this quite likely (II becomes I and aVF becomes aVL).

Usual QRS axis in a normal EKG is about 60, but LA/LL limb lead reversal is commonly missed because P wave axis and QRS axis still fall within normal range when it occurs.

I must say, the PR segment depression in I (actually II) and elevation in R, paired with the lower precordial voltage makes pericarditis an likely culprit, IMO (along with a waywardly-trained nurse).  :)

The Electrophysiologist

Hey, nice ECG and nice example of LL reversal. It is definitely left leg – left arm (LA/LL) reversal. Lead I is II and II is I and III is upside down as expected.

Overall – looks like pericarditis to me. ST depression in aVR is most specific for this. Reconstructing the ECG there is significant St elevation in inferior leads.

I would echo just to check inferior wall moving as ST elevation greatest there, and no effusion (lateral complexes look small).

The Reversal

 Limb Lead Reversal….Reversed

Limb Lead reversal reversed



Reversal by Ameritous Professor Tor Ercleve

The KISS principle

  • Left Arm and Left Leg Lead reversal…
  • Lead I is actually lead II → Lead II is actually lead I and Lead III is inverted
  • aVR is normal; AVL is actually aVF and aVF is actually aVL

  • RA—right arm; LA—left arm; LL—left leg;
  • Clockwise rotation: RA→LA→LL→RA; Anti-clockwise rotation: RA→LL→LA→RA.
  • The (-) sign signifies that the respective lead is inverted


Print Friendly


  1. says

    Brilliant pick-up Christopher!

    Mike, I thought the issue was going to be fluctuating sex of the patient:

    “A 49 year old woman presents to your emergency department with central chest pain. His observations are:’


  2. Andrew Perry says

    Hmmmm. Very interesting. Doesn’t seem to change the most likely diagnosis and hence have adversely affected candidates however exam questions should be model citizens. Will you be submitting this pick-up to the college?
    Andrew Perry, ACEM Trainee

    • says

      I think you’re right that it ultimately doesn’t change your working diagnosis in this case.

      But what happens in the borderline pericarditis case when you run a second 12-Lead in the ED and notice the T-waves have magically uprighted. Would you order a cath based on dynamic changes?

      I know Tom Bouthillet--EMS 12-Lead Blog--had an interesting example of a subtle inferioposterior MI that was missed due to a lead rotation. I believe the cables were plugged in backwards in the ED and the rotation was overlooked, but it was picked up by a regular reader when Tom presented the case online. That got me interested in lead mixups in the first place.

      Another case was one I’d spotted on Dr. Smith’s ECG Blog, and I honestly believe in that case the subtle posteriolateral changes would have gone unnoticed had the T-waves not changed between the two 12-Leads!

  3. Elvis Presley says

    Part of the power of the internet is in anonymity. People can speak their mind without fear of embarrassment (if it’s configured to allow anonymous posting even if requiring login but choice to post anonymously). The trolls are problematic, but are easily ignored. Spam comments can be dealt with relatively easily. I think this was a genuine miss -- although a lot of candidates will go over the cases, there are a lot of reasons why it wouldn’t get picked up and if it was it wouldn’t be commented on. I don’t think being time poor or indecisive are likely to apply to more than a few, but the comment is a bit like the reverse swiss cheese model -- it needs to have a person with the knowledge, the interest, looking at a particular page, inclined to give feedback and a few other factors.

  4. Brian Baird says

    Looks like the “Limb Lead Reversal… Reversed” example has Lead III flipped and reversed. i.e. the T is before the QRS in lead III. A horizontal flip should do the trick and make it right.


  1. […] In the spirit of connecting via social media, this EKG Du Jour hails from the great Aussie blog, Life in the Fast Lane. […]

  2. […] discussion re echocardiography was generally superficial and was the major reason for poor scores.Further controversial analysis of the ECGACEM Fellowship Visual Aid QuestionsFACEM VAQ OverviewFACEM VAQ by YEARFACEM VAQ by SUBJECTRelated […]