Rhythm Challenge #5

@S_Cook_EMTP contacted me on Twitter with regard to a 77 year old male with an interesting heart rhythm.

He subsequently took a picture of the ECG and emailed it to me with this description:

77 yo male with history of COPD, CHF. Initial 4-lead EKG reveals A-Flutter with variable response: 2:1, 3:1, 4:1, and 5:1 is what I saw. Patient would have runs of both bi and trigeminal PVCs then settle back to A-Flutter in the 80s/90s. Then patient developed 20-30 second runs of the attached that ran from ~100BPM to 225BPM.

Best I can think is this is a run of V-Tach. Patient does have an implanted pacer/defib, but relates he hasn’t felt it fire.

Up to about 130 to 140, electrical rate and radial rates were equal.

Otherwise, patient was hemodynamically stable, BPs in the 120s/70s, A&O X 4, with some difficulty breathing.

Patient was recieveing an A&A neb treatment. Initial SaO2 was 75, increasing to 98 during treatment. Heavy smoker. Denies any and all pain and relates he “just feels like $%^*”

Here’s the picture of the ECG in question.

What do you think this heart rhythm is showing?

After I gave my answer, @S_Cook_EMTP shared the following ECGs from the same case, indicating that the treating emergency physician did not agree with my assessment.

However, I still think I’m right!

Of course, I could be wrong (we’ll discuss that a little bit more later).

So, for the sake of Rhythm Challenge #5, to what do you attribute this wide complex tachycardia and why?

See also:

Rhythm Challenge #5 – Answer

Previous “rhythm challenges” can be found here:

What’s the heart rhythm?

Rhythm challenge #1

Rhythm challenge #2

Rhythm challenge #3

Rhythm challenge #4

Rhythm challenge #4 – Discussion


  • Bill C says:

    At a brief glance it looks like an atrial fibrillation with paced beats then a period of (possibly) self-adaptive demand pacing…

  • Tom B says:

    Bill C – What exactly do you mean by self-adaptive pacing? I’m not trying to put you on the spot. Just want to make sure I understand your answer.

  • Dave B says:

    yikes… lol… ok… well, for starters, the wide complexes are not early, but late… the rate is a bit fast for escape beats, so i am wondering if they are in fact paced beats..is it possible that a 12 lead might show pacing spikes i don’t see? also, the morphology of the wide complexes is the same throughout, so the beats seem to be originating from the same place in the ventricles. although the original strip says the rate is “160”, using the rule of 300’s, it seems more like 110, which is a tad slow for V-tach, but not impossible. what it it could be suggestive of, especially if the duration of the “runs” is approximately 30 seconds, is overdrive pacing by the ICD, especially if it started so sense a supraventricular arrhythmia. the duration and rate fit that theory. of course, if they are not paced beats, i am totally off the mark.

  • Tom B says:

    Dave B – A 12-lead ECG will often show pacer spikes (blips) prior to the QRS complex (particularly in leads V3-V5) that are not visible in the limb leads. Remember this case?


  • Martyn Widnes UK says:

    My understanding of broad QRS tachycardias is that they are divided into 2 groups: i) VT and ii) SVT with abnormal intraventricular conduction because of a pre-existing bundle branch block, a rate related BBB or ventricular pre-excitation.

    The fact that 80-90% of broad complex QRS tachycardias are VT (95% if previous infarction) then in all cases we automatically assume VT until proven otherwise.

    In this case (pic 3) i see a tachycardia, the QRS are broad but without a 12 lead can it show a LBBB config? SVT i would say is a possibility but I cannot exclude VT. Inspection of lead II i see ?atrial tachycardia with a varying AV block and possible BBB. However because i cant say for definate it is BBB without a V1 and V6 i would assume and treat as VT.

  • Bill C says:

    Based on what I can recall at the moment, pacers set in position IV or V (I think) act basically as a mechanical stand in for the SA node and vary the pacing rate dependent on the patient’s needs. The sensors are usually either vibration dependent (on the assumption that vibration = activity; anecdotally I have another story based on one service’s ambulances for that to share if I can find the strips) or calculate minute volume (impedance between the unit and pacing electrode). If the patient had an increased minute volume due to his respiratory distress the pacer may be firing in an attempt to replicate the compensatory mechanism (tachycardia) that is likely controlled my medication. Maybe…

  • Terry says:

    First off I would get a better ECG before making any dx. The monitor is in monitor mode not diagnostic. The zoll monitors used to be terrible at this. They would always show st elevation that wasn’t correct. With the physio’s and the philips when you hit acquire 12-lead it switches over to dx mode cleans up some artifact and false st changes.

  • Christopher says:

    Looks like a classic LP12 paced rhythm.

    I can’t STAND the ST-segment distortion on the 3L on a LP12 when my patient has a pacer. Especially if they look awful. My partners start scrambling and I’m asking that everybody calm down and run me a 12L so I can show them the pacer spikes.

  • Dave B says:

    ok… i am going to try again lol… first, the underlying rhythm seems to be regularly irregular for the most part… perhaps a 2:1 block, or a bigeminy of pac’s…seems that the pacer (yes, i am still going with the wide complexes being paced) fires after a predetermined pause after a normal beat…
    now for the “runs”… the pt has something respiratory going on, and i know rate adaptive pacing can fire to compensate for respiratory disfunction or physiologic stress.. i am not very well versed in rate adaptive pacing, but if it is not overdrive pacing, than this explanation seems the best to me, in light of the patient presentation. of course, i could be even more wrong than last time Lol!

  • Nick A. says:

    Ok….let me give it a shot. First of all, the LL linb electrode needs attention to get a cleaer picture. Secondly, where is lead I? Lead one will give you an idea of the cardiac vector. If lead I is negative, then it would be an extreme right axis deviation. This with a positive complex in MCL1 would indicate ventricular in nature (especially if MCL6 is negative). But this is not VT because the rate is less then 100 bpm, and there are PW’s in front of every QRS complexs on the 3rd ecg. I going to assume that lead I is positive giving this a pathological left axis deviation which is classic in a ventricular paced rhythm. Funny that the the “PVC’s are ALL late…not early. Matter of fact, the “PVC’s are exactly 700ms after the (normal) prior ventricular depolarizations.

    Most probable Atrial flutter with occasional paced beats converting to a sinus rhythm with a ventricular paced rhythm.

  • First glance you would say afib with a LBBB with occasional wide PVC’s. BUT the patient tells you he has a pacemaker. He does not say if it is continuous or not. I have learned the hard way with some of my pt’s that just because the cannot feel it does not mean its firing. The wide QRS are due to the pacemaker. Fix the ABCs and BP if necessary like they did and since he is stable leave him alone. This is a PACED RHYTHM in my opinion. Missouri-EMT-P

  • Tamara says:

    I agree with William – about the paced rhythm – definately paced. If your monitor isn’t set to show pacer spikes in 4 lead then do a diagnostic 12 lead to confirm one way or the other. The only time he will feel his pacer/defibrillator fire is if the defibrillator portion of the device is going off. Unlike trancutaneous pacers, the internal pacemakers usually cannot be felt. Also, it is rare to have v-tach with blood pressures that stable…something to consider.
    Prior to the wide complex though, it appears to be a trigeminal rhythm – appears sinus underlying with frequent and regular PVCs. What could be mistaken as a-flutter seems to be a TON of artifact instead.

  • Tavi says:

    the original EKG that you show with the challenge still looks like V-tach to me…

  • phillip says:

    AF leading to trigeminy then AIVR I do not think of paced beats. history I would take bloods get 12 lead, echo prep for lab.
    was there an underlying mi or tamponade ??

  • Paul says:

    I agree with the consensus of AF. Wiith that being said, in the absence of a definitively paced rhythm, I am labelling this as Ashman’s phenomenon.

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