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Wednesday, 15 May 2013

Dextrocardia - #ECGclass Case 30


Welcome.

#ECG Class is an educational blog which runs alongside Twitter.
A new ECG "quizz" is launched most Wednesday evenings, in term time. 

Cases are generally aimed at Primary Care.  All scenarios are completely fictitious, 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 30 

A 22yrs man, previously fit and well, comes to see you holding an ECG.

He explains he is a medical student. He, and few fellow students, were practicing doing ECG's on each other. He became worried when he discovered the 'machine analysis' on his own ECG mentioned a variety of abnormal features.

He denies any symptoms of chest pain/tightness, or palpitations. He has no significant past history, and has never been in hospital apart from a handful of A&E attendances with rugby injuries. 

Apart from being a little overweight, with slightly quiet heart sounds, examination is unremarkable. 

What are your thoughts when you see the ECG? 




Clue: Remember, If you are ever baffled by and ECG, go back to first principals, and work through it systematically. 
Start with the axis, then the P waves.

What is the axis on this ECG? 
Can you describe the P waves in each lead?



Discussion.
Remember the normal ECG axis?

This ECG unusually shows Right Axis deviation of the P wave (the P wave is Negative in aVL and lead I) and Right axis deviation of the QRS complex (between +90 and +120 degrees).

There is also very low voltage/amplitude  in the precordial leads, V4 to V6 . 
Whilst this could be down to patient habitus impeding the electrical reading, or a pericardial effusion, if this was so you would expect to see low amplitude in all chest leads.

A normal ECG shows 'progression of the R wave' in the precordial leads. In other words the relative size of the R wave to the s wave increases gradually from V1 to V5. (V5 is often remains taller than V6 because of the attenuating affects of the lungs).

Look at Lead aVR. It appears more like we would expect lead aVL to look……

In short, voltage and axis deflections are not as we would expect.

This ECG shows dextrocardia.


Classical Features of Dextrocardia on ECG:


  • Right axis deviation
  • aVR often shows Positive QRS complexes (with upright P and T waves) - 
  •      admittedly, not clearly demonstrated in the above example.
  • Lead I: inversion of all complexes, (inverted P wave, negative QRS, inverted T wave)  
  • Absent R-wave progression in the chest leads (dominant S waves throughout), often with smaller amplitude complexes in the left sided chest leads (V4-6)

Note:
A similar ECG picture would be obtained in the limb leads, if the Right and Left limb leads electrodes had been accidentally reversed on placement.  If this was the case, the chest leads would still appear normal showing natural progression of the R wave (maximum amplitude in V3-V4).



Thanks you and well done! You worked it out by logical analysis. :-)
Summary of Twitter discussion next week on #storify.
New case the week after.
H. 



























                                               

4 comments:

  1. Greetings Heather. Just thought I'd direct your readers to an interesting dextrocardia ECG I found during an internet search.
    The link below is to a page that features an unusual example of mirror-image dextrocardia in the presence of left bundle-branch block (LBBB). Hypothetically, if this patient were to go into any form of SVT, then it would produce a wide-complex tachycardia with negative concordance in the precordial leads AND a right axis deviation (RAD). In the absence of a previous "baseline" ECG, these combinations of findings might erroneously cause one to mistakenly interpret this ECG as ventricular tachycardia.

    http://www.ecgcertify.org/img15.gif

    ReplyDelete
    Replies
    1. Thanks for that link Jason. That's fascinating. All sounds a bit too complex for me!

      Delete
  2. Does a right side EKG provide better information on a patient with dextrocardia?

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  3. Thanks Mike, yes. I think if you are looking for electrical clues, when presented with symptoms, you need to do a right-sided mirror image ECG if you have identified dextrocardia.

    ReplyDelete