Video: Axis Determination

So you’ve read our blog, followed us on Facebook, submitted your own case studies, but you’re looking for more. You’re looking for the next big thing in EMS 12-Lead education. As a test run I’ve put together a video, shot Kahn Academy style using a pen and tablet, covering rapid axis determination.

When I learned 12-Lead interpretation in paramedic school, axis determination was covered but it never really sank in. A few folks were comfortable with the I-II-III method (up-up-up, up-down-down, etc). Others, like myself, understood what it meant, what it was for, but never really internalized it as a skill.

The technique I’ve found the easiest is one from Garcia and Holtz’s 12-Lead ECG: The Art of Interpretation. It uses only leads I and aVF and could be called the “quadrant method”. The best part is the method is easy to apply even when your own heart is racing!

Rapid axis determination using only leads I and aVF

The following video assumes you have a basic understanding of vectors and axes. The objective is to teach you a rapid means of axis determination using only leads I and aVF.

Let us know if this is helpful and let us know if you want more!


  • AW says:

    Love the video idea, great way to present, hope you do more of them.  Great review of axis deviation.

  • Mike says:

    Good video. Maybe the next one could be on the importance of axis deviation and what each axis signifies and how it can aid in a diagnosis

  • Nick Adams says:

    Very nice video simplifying axis determination.  I like the fact that you incorporated lead II as a determining factor to differentiate between physiological and pathogical LAD.  Most literature I've read however, use -40 degrees as the boarder between the two.  I personally use the lead I,II,and III method of determining axis because if I had AVF, it's because I did a 12 lead and the numbers are given to me as the QRS axis.  I like to play a game with it.  Since the patient is put on the 3 lead ekg first before the rest of the 12 leads are applied, i'll try to compute what the axis will be before the 12 lead is actually done.  I'm usually within 10 degrees, but I have been as close as 1 degree……the geeky things paramedics do in the field to stay entertained.
    Overall the video is makes axis determination easier to understand.  Thank You.
    Nick Adams NREMT-P, FP-C

  • Good job Chris.  To make things easier, I teach my students to shade in the portion that you know the axis is not in.  Up in I, shade the left side.  Up in aVF, shade the top.  Same idea, but the quadrant that isn't shaded is much easier to identify.  
    I love the idea of creating videos like this. In fact I have been flirting with the idea of doing a video podcast, I've just been too busy.  
    I believe a video about vectors is in order.  Once I understood vectors, everything else became so much easier.  
    Nice Work!!

  • FireMedic says:

    Great video. Keep them coming.

  • Dennis says:

    A+  MORE!

  • Christopher says:

    I find it much harder to localize using only I, II, and III and I'm an engineer! If only the standard 3 leads were orthogonal it would make things much faster. The nice thing is once you get this method down, you can apply it to any sets of leads and after a while you begin to comprehend what you're seeing as a vector. Then you can use just I, II, and III to get pretty close. I like II, I, aVF as my 3-leads on my LP12. I have my rhythm and axis almost immediately without shooting a 12-Lead.
    And thanks for the feedback from everybody!

  • Jukka says:

    Great video, I enjoyed it a lot! Made things a lot clearer! I agree with Mike, maybe next time a video about using those findings in the interpretation of the EKG.

  • Simon says:

    Nice job guys, as always…love the tablet format…the only issue I have is waiting for the next one ( I know you have nothing else to do)

  • Dodge says:

    being new to the world of 12 lead e.c.g's i have found this site more than informative but being in the old school i find it better to be able to see the concepts in action so the idea of providing video instruction is a very worth while excersise, as being from the old school i get lost in the words of text and get more benifit of seeing and hearing the concepts so more video content  would be a welcomed addition

  • Donald says:

    Loved the Video.  I am an EMT-B, reading through Dubin's book at this time.  Watch this video before the Axis chapter, made it make even more sense when I did read it. 

  • scotty says:

    Great concept. User friendly and easy to understand. Would be great to view more explanatory EKG videos.

  • Nick Adams says:

    Thanks for the insite Chris,
    LOL…..I never even thought of monitoring I, II and aVF (one lateral and 2 inferior).  I guess it would give you the views that you want.  I monitor I, II, and III which give you the same one lateral and 2 inferior.  I know you know all this, but I'm stating it anyway because I've seen it a million times where people monitor II, III, and aVF (All inferior).  Why would someone limit themselves by monitoring one area of the heart?
    Anyway, you did a great job explaining axis.  A great start to understanding the relationship betwwen lead vectors and cardiac vectors.
    Nick Adams

  • Christopher says:

    I'm with you Nick, but I would caution that monitoring any set of leads in non-diagnostic frequencies is useful only for rhythm interpretation and not for localization of injury. Therefore I avoid terms like inferior, lateral, etc when talking about monitoring leads.

    Far too often I hear things like, "having II, III, and aVF gives us a quick look at the inferior wall". No, it gives you a quick look at the rhythm 🙂

  • Nick Adams says:

    True True.  We're talking around the same area.  All I'm saying is that you are looking at two areas of the heart instead of one, whether it be in diagnostic mode or not.  I can't count the number of times that I put someone on the monitor that showed ST evevation in II and III, but had a normal 12 lead.  On the other hand, every time I had a patient with an inferior MI, thier 3 lead also showed ST segment elevation.  Granted, it's not enough to call a cath lab alert,  but you can see a CHANGE in these leads even though it is of non-diagnostic quality.
    A view is a view even if it is not in diagnostic quality.  Of course, if a patient is symptomatic or suspecious of an MI, then a 12 lead is always done, and the leads left on because the LP-15 will spit out another 12 lead if there are changes.  It would be nice to view all 12 continuously indiagnostic mode, as with the Philips HeartStart MRx model.
    If I do a transfer of a cardiac patient who has an anteroseptal MI with elevation in V1 – V4, I'll monitor the patient in MCL1 during transport.  This way, I can see the rhythm and obvious changes.
    Monitor mode exagerates things.  It may create a false positive, but I'm not so sure of a false negative.
    Enjoying our conversation,
    Nick Adams

  • akroeze says:

    Just curious, as a general rulehow good are the monitors at calculating axis?  As in are they "trustable" when they give you a number?

  • Christopher says:

    With a good quality ECG I've not seen it go crazy for QRS axis. P-wave axis it is pretty bad.

  • ilies2000 says:

    great video  very simply despite my poor english  thanks

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