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Monday, 8 October 2012

#ECGclass Case 13 - AF or not AF?


#ECG Class is an educational blog which runs alongside Twitter.
A new ECG "quizz" is launched most Monday evenings, in term time. 
Cases are generally aimed at Primary Care. 
All scenarios are completely fictitious and theoretical, but based on commonly occurring presentations in General Practice. 
This is an educational site, intended for healthcare professionals and shouldn't be construed as patient advice. 

Please use the Hashtag #ECGclass on Twitter, if you want to ask the patient any questions, or request any further investigations. Alternatively, please join in discussion and leave comments below.

Remember there are no right or wrong answers!  

ECG interpretation is often open to debate, and will usually evolve and change as new information becomes available.  Everyone's opinion is valid, and useful for others, as the evolution process takes place. 
Together we will try and form an interpretation based on the trace, and information, we have in front of us. 
Don't worry if you disagree - shout up and share your thoughts - the diagnosis is often arguable on the basis of a 12 lead trace, and may only become more obvious when a longer rhythm strip is available. 

Please feel free to join in, but most important of all, have fun! :-)


#ECGclass Case 13

This weeks ECG class is a confidence teaser. 
It builds a little on the learning point of last week.  How comfortable are you with uncertainty? Are you confident enough to challenge your ECG machine's analysis?

Below are 6 ECG's.
One or more may be Atrial Fibrillation. One or more are not.
Which ones would you be confident enough to plough ahead, and treat as AF?

If you want to ask any questions, or make any comments, please use the hashtag  #ECGclass. 
Remember, this is a learning forum and not designed to catch anyone out.
These ECG's have been specially selected because they are not straight forward, so don't feel disheartened if you are unsure. (Most of them were passed to me by my GP colleagues who were uncertain about some aspect of them. For one of them, I sought a consultant cardiologists opinion. Reassuringly, even he wasn't 100% sure!)  As always, it's just a bit of fun.

Take your time. Answers and discussion to be posted later.

Sorry about the poor resolution quality of some, but we're not looking for any detailed measurements here, so should be OK.

1). See ECG Below
a.   Is this AF?
b.   If not, what it is?



Discussion:
1a).  Not AF - Ignore your machine - P waves are clearly visible
1b).  Study the rhythm strip. 
P waves are clearly visible, but don't have a consistent relationship to the QRS. i.e. The PR interval is variable. The Rhythm is irregular. 
Starting with the 3rd complex on long lead II: This QRS complex is preceded by a P wave, but the PR interval is prolonged (>5 small squares). The following complex has an even longer PR interval. The P wave of the subsequent complex is so premature that it is lost in the previous T wave. (Note the distorted shape of T wave). This series of 4 complexes is then followed by a pause, before the cycle repeats itself. It's a bit tricky without a longer rhythm strip, but on this 12 lead, it looks like Mobitz Type 1, second degree Heart Block - Wenckebach

Features of Wenckebach:

  • P-R interval progressively lengthens until P waves fails to conduct
  • P-R interval then resets to normal
  • The R-R interval progressively shortens
  • Cycle repeats
  • Usually benign - Observe, check medications. (The patient above actually required pacing - symptomatic during prolonged pauses on 24hr ECG)



2). See ECG below
a.   Is this AF?
b.   If not, what it is?




Discussion:

2a). This is Not Sinus Rhythm - Ignore your machine! 
Neither has this patient got Ventricular trigeminy or  Multifocal extrasystoles. There is a wandering baseline on the rhythm strip at the bottom, typical of movement artefact, which will also account for the  bizarre pattern in the middle, misinterpreted as ventricular ectopic. Note that it is seen in limb lead II (on rhythm strip) but not mirrored in the chest leads.  Nor  is there a short PR interval (un-measureable without P waves!)

2b). Can you see P-waves? If you are ever uncertain about P waves, look carefully at V1 and V2 - these are the two leads in which P waves are usually best seen. I can't see them on this ECG. The rhythm is irregularly irregular. You guessed it. This is barn door AF - missed by the machine. 




3). See ECG below
a.  Is this AF
b.  If not, what it is?



Discussion:

3a). Now this is a bit more tricky. You definitely need an element of suspicion, and a piece of paper to map the complexes here. You won't be surprised to hear that it's not AF and the machine is wrong again. 
The LVH suggestion is more believable (voltage criteria met in Lead I, and possibly aVL - see earlier class on LVH).  There is a slight tachcardia here, at rest. 

3b). If you map out the rhythm strip - it's the only way of being sure here - you will see that interval between the 1st and 2nd complexes, is different to the interval between the 2nd and 3rd. BUT - the interval between the 4th and 5th complexes, is exactly the same as that between the 1st and 2nd. In fact, if you 'skip' every 3rd complex on the rhythm strip, the R-R intervals are identical. Every 3rd complex is an atrial ectopic.  This is Atrial Trigeminy.  Subtle one! No action necessary. Reassure patient. 

A re-assessment of BP is advisable.  The LVH and atrial ectopics raise the suspicion of a possible manifestation of atrial hypertrophy. 


It may be difficult to see on this reproduction, but if you can zoom in on leads V1-V3, I was very suspicious here about a possible delta wave? The PR interval in these leads looks so short as to be slurred into the QRS.  What do you think? 



4). See ECG below
a.   Is this AF
b.   If not, what it is?





Discussion:

4a). Firstly, This is the same patient as in example (3).  Who spotted that?!
No. It's Not AF. 
I thought it would be useful to repeat once her rate had settled down a bit to get a closer look at those possible delta waves/PR interval. This was taken  24hrs later. 

4b). You can see she has now reverted to Sinus Rhythm. 

Look again at leads V1 and V2 at this slightly slower rate. The PR interval still appears short, but is clearly separated from the QRS and I don't think there's a delta wave here.  Given this finding and the voltage criteria for LVH, makes me think a 24hr ECG and ECHO may be helpful here  - especially if she reports any runs of palpitations.



5). See ECG below
a.   Is this AF
b.   If not, what it is?




Discussion:

5a). This is NOT AF.  This one was really just to see who was paying attention last week! Same ECG as discussed in detail in Case12. Should have recognised it second time around? ;)
Well done if you did. 

5b) As discussed last week, this ECG as seen, may well be Multifocal Atrial Tachycardia, but if you remember we needed a longer rhythm strip to help sort it out. 
(For those wondering - this is the one I took to a consultant cardiologist - and he wasn't 100% sure - nice to know. I think?)  The longer rhythm strip definitely helped here.
   



6). See ECG below
a.  Is this AF?
b.  If not, what it is?




Discussion:

6a). YES!!  This is AF.  Just popped in to remind you how straight forward it is to spot AF! So why can't the machines be as reliable as you? Switch off the machine analysis and start looking at ECG's yourself. ;-)

Well done everyone. Shall we have a quick and easy one next week?
(Collapses with exhaustion)

Thank you all once again, for your fun and input on Twitter.


HW#ECGclass/Ovt2012

1 comment:

  1. maggie.danhakl@healthline.com18 April 2014 at 01:01

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