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Wednesday, 19 June 2013

Hypertrophic Cardiomyopathy in a nutshell - #ECGclass case 32


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! :-)

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 at the end - It's really helpful to know how many people are 'out there', finding this class useful.

Here goes then. 


#ECGclass case 32.

An anxious Mum, re-presents her 13yr old son, for the second time, with chest tightness on exertion. 
You last saw him 8 weeks ago, when he described breathlessness and chest tightness, often on exertion (during football and running), but occasionally at rest as well. 

Despite there being no family history, you were fairly convinced this was asthma, and suggested a trial of inhaled bronchodilator, and a Peak Flow diary. 

The peak flow diary is unremarkable, and he reports no symptomatic benefit from salbutamol.

You remain unimpressed by this tall, thin and healthy looking, active teenager, but mum seems unduly concerned.
Under a little pressure you agree to do an ECG to reassure.
After all, 14yr olds can't get angina.... Can they?

You have planned to review him in a couple of weeks, but as soon as your practice nurse has done the ECG she brings it in for you to see:




What are your thoughts now? 

Does it look normal?

Which features worry you?

Any more questions you want to ask?


Discussion


We can see P waves, and the rhythm is regular with a reasonable rate.
What is apparent is the very large  R and S deflections, with appearances of downsloping ST depression in the precordial leads.

Could this ECG be just down to habitus?

No.  We've previously discussed ECG voltage criteria for LVH and how tall, thin, men and adolescent boys may have apparently large wave amplitude because of reduced impedence from the chest wall and soft tissue in electrode recordings.  Hence the importance of checking the limb leads.  If the deflections are similarly enlarged in leads I and aVL then remember that stature and habitus play no role in these leads.
The reverse is also true. Genuine LVH is unlikely, if the large amplitude waves are confined only to the precordial leads. Always study lead I and aVL when considering a diagnosis of LVH.



This ECG is highly suggestive of Hypertrophic Cardiomyopathy (HCM), and coupled with the symptoms reported I would get straight on the phone to a Paediatric cardiologist, or adult cardiologist with an interest in inherited cardiomyopathies to ask what to do next.

His symptoms are relatively stable, but worrying - he does get symptoms at rest on occasions.
Hopefully some telephone advice this evening will end in an agreement to have him seen in the morning when an ECHO and CXR can also be performed.

I would ask him not to go out running - or play football -  this evening!


Cardiomyopathy


Cardiomyopathy is a disorder of the muscle of the heart. It can be divided into

  1. Dilated Cardiomyoapthy - when the heart is dilated
  2. Hypertrophic Cardiomyopathy (HCM).  When the muscle of the heart is thickened, it is known as "Hypertrophy". The commonest cause for this is secondary to hypertension, but HCM occurs in the absence of raised BP. The upper part of the septum is commonly affected, and a thickened septum can obstruct the outflow of blood from the heart. This is termed Hypertrophic Obstructive Cardiomyopathy (HOCM)
  3. Restrictive Cardiomyopathy
  4. Arrhythmogenic Right Ventricular Cardiomyopathy 

Symptoms of HCM

Most children and young adults remain completely asymptomatic, but HCM is a well recognised leading cause of sudden cardiac death in young athletes.  For this reason, some advocate screening for HCM in young adults. However - screening ECG benefits are hotly debated.

Occasionally, symptoms can include:

  • Shortness of breath. On exertion - or in severe cases, at rest. Secondary to increased stiffness of the left ventricle which impairs filling, and raises left sided heart pressure)
  • Angina. On exercise, or at rest when it is more severe. Despite normal coronary arteries, oxygen supply is insufficient to meet the demands of the thickened muscle.
  • Palpitations. Secondary to arrhythmias generated by the abnormal muscle.
  • Dizziness and syncope.  These occur more commonly on exercise, but again, may occur at rest. (Secondary to reduced output or arrhythmias).
  • Sudden death.

Familial HCM is inherited in an autosomal dominant fashion, so children of an affected parent have a 50% chance of inheriting the  mutation. Family history of sudden, cardiac death in a young adult is very important to establish. However, de-novo gene mutation is also possible, so lack of family history does not exclude HOCM.



Typical ECG changes of HCM:


  • LVH results in large waveform amplitude and non-specific ST and T wave changes
  • Asymmetrical Septal Hypertrophy can produce deep and narrow (dagger-like) Q waves in the lateral and inferior leads.
  • LV Diastolic dysfunction (from a stiffened left ventricle) may cause Left Atrial hypertrophy, with signs of enlargement (P mitrale) on the ECG.
  • There is some association between HCM and WPW syndrome, so a delta wave may be seen.
  • Atrial Fibrillation and SVT's are common. Also Ventricular arrhythmias, such as VT/VF,  can be a cause of sudden death.


Lesson of the week:

Teenagers and young adults are not likely to have Coronary Athersclerosis - but coronary artery disease is not the ONLY cause of angina. 



A couple of further links for those interested (Thanks to Richard Bogle):
ECG's interpretation in children 
Standardised criteria for ECG interpretation in Athletes



Thank you. :)

I've kept this very brief as I can't pretend to be an expert in HCM/HOCM - but if any experts out there want to add their penny's worth in the comments below, and shed some pearls of wisdom, that would be very welcome. Thank you!  H.






7 comments:

  1. Hello...
    Interesting case. I do not see the "dagger Q waves" you talk about in this ECG.

    In addition, how do you explain the constellation of ST changes consistent with subendocardial ischemia (ST elevation aVL, with wide spread ST depression in the absence of tachycardia)?

    thank you,
    David

    ReplyDelete
    Replies
    1. Hi Dave. Thanks. No, they are not present in this case. Not all features are present in every case.
      Here is an example of a HOCM with deep septal Q waves:

      http://www.learntheheart.com/GAHOCMECG1.html

      Although the ST changes on the ECG in this case do indeed look ischaemic, they are in fact, not. These are the typical changes seen in marked LVH as a result of repolarisation of the hypertrophied septum and ventricle.
      LVH with strain pattern mimics ischaemia.
      H.

      Delete
  2. Are the ST changes not just the repolarisation abnormality you get with severe LVH? I was always taught that if depolarisation is abnormal then repolarisatiin will be too.

    ReplyDelete
  3. Hi Martin. Thanks. Yes you are quite right. I'm sorry I didn't make this point clear on the blog.
    The ST changes seen on this ECG are NOT a sign of ischaemia, but just the abnormal reploarisation of LVH (as a result of hypertrophied septum and ventricles).

    To clarify. This patient's chest pain may well be a symptom of his HCM (HCM most often asymptomatic) but his symptoms are 'incidental' to this ECG which simply shows LVH with abnormal repolarisation.

    That's how I understand it, anyway!
    Thanks for highlighting the point, Martin.

    ReplyDelete
  4. Here is a great example of the "typical" changes associated with LVH/Strain pattern:

    http://ems12lead.com/2011/07/63-year-old-male-cc-shortness-of-breath/

    So, do you mean to say that these changes are associated with RVH/strain or biventricular enlargement? Or perhaps there is something else going on here, because the changes on this ECG do not seem consistent with LVH/Strain pattern.

    -David

    ReplyDelete
  5. I agree. Not consistent with simple strain pattern (strain pattern is commonly inferolateral). I can't recall all the subsequent ECHO details for this particular ECG - the only information I have stored with it is Idiopathic Hypertrophic Cardiomyopathy, but can try and find out for you! H.

    ReplyDelete
  6. actually it is a case of Apical HCM, thats why no Dagger like Q wave, which is seen in Septal DCM. in Apical HCM ,deep T wave is Seen in precordial leads (commonly in v3-v6),with inferolateral leads, and T wave amplitutes changes with subseuent ECGs. furthur there will be no history of Hypertension in case of HCM usually.

    ReplyDelete