Rhythm Challenge #3

Thanks to firefighter/paramedic John Wright for sending in this interesting rhythm challenge.

There are some interesting clues in this ECG strip to help you identify what’s happening.

What say you?


  • Christopher says:

    Marching it out, 3AVB. First strip has either a ventricular or junctional escape at 50 bpm, atrial rate of 90bpm. Given the rate, I'll say junctional escape rhythm (which appears to be moving slower through the RBB).End of the strip shows a change in escape foci (LBBB morphology?) to a lower rate, so probably lower in the ventricles at the end of the second and onto the third (V: 30-40bpm, A: 90bpm).I have a marked up image with A's and V's that I used to help myself. Will find a place to upload.I'm thinking there is some ischemia progressing to a point where the entire AV junction/HIS is starved.

  • Anonymous says:

    I absolutely agree with the 3AVB and change in escape focus . There are still pulses adequate to create a wave form on the pulse ox which suggests that, for the time being, this patient has some sort of CO. I think QRS morphology is the most remarkable thing about this strip. The initial and secondary foci both have low voltage QRS with the second (likely) ventricular focus having a QRS that looks almost exactly the same as that of the surrounding P waves. Their is clearly still dissociation with the P's running all through and around the QRS but this might be a confusing situation to deal with if this guy was crashing right in front of you.

  • Jesse says:

    My first thought was a 3AVB, with a failure to pace that coincided with the lack of waveform on the pleth.But even what I construe as paced complexes at the beginning of the strip, fail to explain how he's still breathing for the latter half.Im so tired right now though, that the more I look at it, the more it looks like little rolling hills on paper. Ever have those days?

  • 3rd degree AVB then ventricular asystole. Not sure what the out of sync beats are at the end and the P wave morphology indicates some sort of atrial enlargement.

  • Tom B says:

    Christopher -I wouldn't be quick to classify the escape rhythm either way (junctional or ventricular) without viewing it in a other-than-isoelectric lead.While I can see why you suspect a change in escape foci, I wouldn't jump to conclusions about that either.Let's say for example this escape rhythm shows LBBB morphology and happens to be isoelectric in lead II, and that we are viewing lead II.If we were viewing lead I we'd see nice upright monomorphic QRS complexes and in lead III we'd see negative QRS complex.If that were all true you'd scarcely notice minute changes in QRS morphology in the isoelectic lead, even if it technically went from negative to positive.In my experience, you can have a change like that just by sitting a patient up on the gurney.Would you like to submit your markup of the strip before I post Mr. Wright's?Tom

  • Tom B says:

    Anonymous -Thank you for noticing the waveform, which I am assuming is a pulse-ox waveform as opposed to invasive monitoring.That's one extra way you could help distinguish between P-waves and QRS-complexes in this rhyhtm strip, since as you say, the QRS complexes happen to look very similar to the P-waves which is why this rhythm strip is interesting and difficult.Tom

  • Tom B says:

    Jesse – I have absolutely had those days! If you stare at ECG rhythm strips for long enough, especially if you're sleep deprived and stressed out, they will eventually turn into squiggly lines on paper.Tom

  • Tom B says:

    Adam -Could you elaborate with regard to the sync beats? I don't want to assume what you meant by that.Tom

  • Geoff says:

    I'm going with 3rd Degree AV Block, that progresses to ventricular asystole or a really, really slow bradycardia. When looking at the 2nd strip, the 2nd complex appears a little taller than the preceding complex (P-wave). The complexes that are grouped together also appear a little taller. Granted honestly, I don't know if I would have picked up on this in the back of an ambulance with somebody crashing in front of us.We don't use the pulse oximetry waveform in our day to day monitoring, so I have a question about this. When I was comparing the negative QRS complexes at the beginning of the strip to the pulse ox waveform, the pulse ox waveform seemed to consistently register approximately 0.4 seconds after the QRS. Is this normal?

  • Christopher says:

    Tom,I'm not sure I all the way follow you on the change in morphology bit and the isoelectrics, but I'm beat so I may just need additional processing time. I was looking at the rate changes and what I perceived as morphology changes…ok maybe I'm getting what you mean about isoelectric writing this out. Still need more processing though 🙂Marked up ECGLadder diagramGeoff,If the pulse oximeter was on a finger, 0.4s seems reasonable. That does appear to be a mighty nice waveform for what appears to be an awful rhythm 🙂

  • Geoff says:

    Thanks Christopher. Does anybody have any idea if the pulse oximeter waveform is an accurate way to "measure" the heart rate for somebody with a LVAD. I saw some information the other day about the Heartmate II regarding the lack of a pulse or B/P and read some articles, but never saw anything about a pulse ox. I suppose blood is going by, but not in pulsations… Sorry, I know this is the "12 Lead" blog, but I figured somebody might have an answer or know where I can look.

  • Christopher says:

    Geoff,We have a guy with an LVAD in our area and the only way we've been told is appropriate to get his "pulse" is to use Doppler. I've also seen nurses get a systolic BP with Doppler on him as well. LVAD's are really weird/cool to listen to; hard to assess lung sounds with it going !

  • Tom B says:

    Christopher – By creating a ladder diagram you have officially joined me, Nick Nudell, and Klaus Skrudland in the ranks of ECG super-nerds.You now qualify for a vanity plate for your privately owned vehicle.Tom

  • Tom B says:

    Geoff -Yes, that's normal! Depolarization comes before contraction. I remember thinking that was messed up first time I noticed it! It wasn't with an SpO2 waveform. I was just monitoring a radial pulse and comparing it to the cardiac monitor for a bradycardic patient.Tom

  • instead of a ladder diagram, i mark p waves on scrap paper and use that as sort of a ruler. does that make me a nerd or macgyver? haha.

  • andy says:

    christopher, wth LVADs- there is no pulse so u will not get an spo2.  LVAD pts are completely differnet pts and if you have one in your area i would suggest doing some research, possibly talking with there LVAD coordinator, or your local base as to how they would like you to handle these pts

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