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Monday, 23 July 2012

Digoxin and The Heart


#ECGclass - Discussion Case 3

A well 83yrs lady attends surgery for her ‘annual review’. As part of this review a routine ECG is done by the practice nurse, which shows the following:





The nurse shows the ECG to the duty GP.

Q1. What chronic condition was being monitored at her Annual review? 
Q2. What is she taking for this condition?
Q3. What action should the GP take now?



Q1
Ignore the funny shaped ST segments for the time being. Start as always, by checking the background rhythm. Are there P waves present? Are the QRS complexes regular?
As most of you worked out, the answer to both is ‘no”.
This ECG shows an underlying rhythm of AF with a good rate control (around 80 bpm ventricular response).

The ‘quick’ way to measure rate on an irregular rhythm is by counting the number of complexes in 6 seconds (30 large squares) and multiplying by 10.
In this ECG, looking at the long lead II strip, there are 8 complexes in 30 large squares. So 8x10 = 80bpm.

So, this lady was attending for her annual AF review. As AF is a precursor to many other cardiac conditions, an annual ECG helpful; but arguable. Annual pulse rate check is bear minimum.
So far so good.

Q2
This lady is taking Digoxin. The ST-T complexes here are “scooping” – consistent with Digitalis ‘effect’. 

For the Digitalis effect, remember Salvador Dali:   



In the Digitalis effect, the ST segments are often likened to a ‘reverse tick” or to shape of Dali’s moustache! Never to be forgotten again.

The important learning point here, is that the digitalis ‘effect’ does not necessarily mean toxicity...and ECG features can often be seen when digoxin levels are in the therapeutic range.
So, ECG changes with Digoxin can be either:


1. Therapeutic (Also known as the Digitalis “Effect”)

  • ST segment depression resembling a ‘reverse tick’
  • Reduced T wave
  • Shortening of the QT interval


2. Toxic
  • T wave inversion
  • Arrhythmias


Q3
This lady appears clinically well and denies any untoward symptoms. Given the changes seen on her ECG, we can probably assume that this is simply a digitalis ‘effect’ and no treatment or adjustment to her medication is necessary. It wouldn’t harm to check her Digoxin levels (and while you’re on K+ - just in case!) for reassurance, but this isn’t necessarily essential.
  • In summary - Treat the patient, not the ECG 
    No action necessary.

    Well done all! 


Supplementary Information on Digoxin:


Foxglove (Digitalis Purpurea)
Digoxin, derived from Digitalis lantana, was first described by William Withering in 1785. It is sometimes used to increase cardiac contractility (positive ionotrope) and as an antiarrhythmic agent to control heart rate, for example in fast AF. But superior rate-limiting agents, such as beta-blockers, have superseded it’s use as a first-line agent. It’s role remains important in AF associated with heart failure.

Symptoms of Digoxin Toxicity
Lethargy
Nausea and vomiting
Diarrhoea and abdominal pain
Visual disturbances, hallucinations and delirium
Severe headache
Almost any dysrhythmia may occur except sinus tachycardia, SVT and rapid AF.


Below is an ECG after Digitalis overdose, in a very unwell patient with all above symptoms and digoxin levels of 4.7ug/L (Therapeutic range 1-2 ug/L) : 






Note the irregular bradycardia, AV block and T-wave inversion. Hopefully, the history and examination would be clues here!

Thank you!


H.Wetherell/June 2012/#ECGCLass 



Tuesday, 17 July 2012

Percarditis - a specific cause of ST elevation


Pericarditis
Pericarditis is a cause of ST elevation which often throws us.

If faced with uncertainty, in patients who are not unwell enough to warrant admission, and in whom the chest pain history does not suggest an acute coronary syndrome, then the most helpful test to support the ECG, is a serum CRP (rarely normal in pericarditis).

These patients are often younger, with a lingering history of onset of symptoms, and frequently present to GP. (Some are inevitably admitted via the paramedic 999 service, having presented with chest pains and an abnormal ECG).

Typical ECG of Pericarditis :

Key Points:

  • ST segment elevation is widespread across multiple leads (not localised as in STEMIs) and there is no reciprocal ST segment depression
  • Scooped or saddle-shaped ST segments, Often notched.
  • Associated PR segment depression (usually elevated in aVR).

Symptoms:
Often associated with viral prodrome – such as a bad cold with aching joints. (inflammatory markers raised)
Longer-lasting symptoms than acute MI.
Pain can be eased sitting forward, and may be worse when laying back.

Examination/Ix
Sometimes associated rub ("footsteps in the snow")
CRP usually significantly raised (normal CRP pretty much excludes pericarditis)
ECHO may reveal small pericardial Effusion.




Monday, 16 July 2012

Different Patterns Of ST Elevation

The main purpose of the last case, was to highlight normal variation patterns of ST elevation. In my experience, many people (including myself!) get hung up over whether ST elevation is significant, or not.

As always, the history is crucial. In an unwell patient, with other symptoms, or past cardiac history, assume any ST elevation is sinister, until proved otherwise.

However, if you've done an ECG purely to reassure an anxious patient, who is other wise fit and well, and you are convinced by the history and examination that this is non-cardiac; then think seriously about whether the changes you can see are simply high take-off.



Here are some common patterns of ST elevation, I have tried to highlight the main differences between them:

1. Antero-lateral STEMI - Localised, convex ST segments:

2. Pericarditis -  Non-localised, scooped or saddleback ST changes, often notched:



3. Benign High Take-off - Often antero-lateral, but different shape form to STEMI.  Often with notched J point seen in V4, and Tall T-waves:

4. Left Bundle Branch Block - The notable feature is the wide QRS complex. The ST segments and T wave changes are opposite (discordant) to the dominant QRS component  (The T-wave and ST changes are in the same direction as each other).  There is ST elevation pattern in V1-4 :



Hope this is helpful.
We'll look at each, more specifically, in a later ECG quizzes . So be warned, keep them in mind! ;)






Friday, 13 July 2012

Homepage :ECG class - What's it all about?

Keeping ECG's Simple


The aim of this blog is to improve confidence in ECG interpretation, and encourage more doctors, especially GP's,  to 'have-a-go'. Keeping it simple - but safe!

There is already a wealth of excellent blogs and social media outlets, for the more acute-care ECG interpretation (all that really clever stuff ). My intention is to keep this site purely for those every-day-ECG's which are thrown in front of us in General Practice, by our diligent Practice nurses.
Which of those "incidental" ECG's do we need to action?

I will assume a basic knowledge about heart anatomy, its conducting system, and the views obtained by a 12 -lead ECG.

What is #ECGclass all about?



#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! :-)

***

If you feel confident enough to join in, that's fantastic, but equally its great if you just prefer to watch and learn quietly.

Please feel free to leave any comments - It's really helpful to know how many people are 'out there', finding this class useful.

Acknowledgments

I'd especially like to thank Jo Yaldren, and all contributors to her Diploma Module "ECG Interpretation for General Practitioners" offered at Teesside University Department of Health and Social Care, for giving me the motivation and confidence to embark on this blog.  I can highly recommend this module for those interested:

http://www.tees.ac.uk/parttime_courses/Health_&_Social_Care/University_Certificate_in_Continuing_Education_ECG_Interpretation_for_General_Practitioners.cfm

Tweet to Jo directly for more information: @JYaldren.

The majority of the ECG's on this blog are my own, but I would also like to thank the following for kindly allowing me to 'pinch' some of their images where necessary:
www.FRCA. co.uk
www.ECGpedia.org (J. De Jong)
www.ECGlibrary.com (Dean Jenkins)
www.wikiward.com
www.ecg.utah.edu (Frank G. Yanowitz)

Some Quiz ECGs' will follow on over the next few blogs! 

Have fun and enjoy :)

Sunday, 1 July 2012

About Me

Hi. Thank you for looking at my 'blog', which isn't really a blog at all.

This 'Educational blog'  was developed from a very casual Twitter forum. The main reason for setting this up was to offer some easy to follow ECG 'refresher' notes.  It's is aimed at those with previous, but now somewhat rusty, knowledge.  A situation I found myself in, for many years!

Please remember, I don't know everything! In fact, I know very little - I'm just a plain old ordinary GP. So if you think I've got it wrong, say so!  I rely on all those cardiology geeks out there to keep me straight.

Take a look at #ECGclass on Twitter, where some curious or classic ECG's are shared for discussion and fun - yes, like any puzzle, I think they can be fun!  They are meant to be simple, and, confidence boosting.... ;-)

I graduated from Nottingham Medical School in 1988, and completed my VTS Training for General Practice in Northallerton in 1994. I am a Part-time GP partner in Middlesbrough, with a special interest in Cardiology, also working within the Rapid Access Chest Pain Clinic, at The James Cook University Hospital.

Despite my interest in 'chest pain' (of any origin), my real passion lies in Primary Care, and the diagnostic dilemmas posed, especially when an 'incidental-ECG' throws up something slightly unexpected....

Living in North Yorkshire, I am married, with 3 children. My passions include The Great Outdoors - walking, hiking, camping and skiing (the latter two, preferably not together);  as well as good food and good wine! :-)