Like it? Share it!

Tuesday, 11 September 2012

Voltage Criteria for LVH - case 9


#ECGclass Quizz case 9                                                    

This 56yrs lady attends for a well-woman BP check.  After 3 repeated measurements, a minute apart, her mean BP is 146/90 so the Practice nurse decides to do an ECG, in accordance with the practice protocol. 
        Image courtesy of www.frca.co.uk 

What is your impression?
Does she need any further investigations?

This ECG is compatible with Left Ventricular Hypertrophy (LVH).  
It shows voltage criteria for LVH, in leads I and  aVL.  
As no other criteria for LVH are met, it is often better to say “This ECG meets the voltage criteria for LVH”, rather than diagnose hypertrophy.

In accordance with latest NICE Hypertension Guidelines, you may want to offer this lady an ambulatory BP monitoring (ABPM), or Home BP monitoring (HBPM), for confirmation of diagnosis. Her CVD risk, and any target organ damage, should also be assessed.  
Whether she turns out to have Stage 1, or Stage 2, Hypertension on the basis of her ABPM, her LVH will certainly sway you towards a lower threshold to treat. 
Unless it is likely to change your management plan, an ECHO is not necessarily required to confirm diagnosis of LVH. 
(See 2011 NICE CG127 Hypertension Guidelines for care management pathways).   


Discussion
The main purpose of showing this ECG is to discuss the various voltage criteria for LVH. 
Don't just look at the chest leads! 
Interestingly, there is no one universally agreed criteria for diagnosis of LVH by ECG.  A few of the more commonly accepted ones are listed below. 

A normal Left ventricular wall is 9-11mm thick. Larger than this is defined as LVH, and can only be diagnosed by ECHO measurement. Various ‘voltage criteria’ seen on ECG, however, can be suggestive of LVH.

The Left ventricle is represented by leads v5 and v6, so in LVH, we expect the ‘R’ waveforms to be enlarged/tall in these leads.  (Conversely, we expect the ‘S’ waves to be deep in the right ventricular leads, that is V1 and v2).

Suggested voltage criteria for LVH include:
  • ·      The sum of the S wave in v1 or v2, PLUS the R wave in v5 or 6 35mm,   OR,
  •     The sum of the deepest S wave +  the tallest R wave  > 40m
  • ·      Any single, R or S, wave in leads v1-v6  45mm
  • ·      The R wave in aVL   11mm
  • ·      The R wave in lead I 12mm
  • ·      The R wave in aVF 20mm
Generally speaking, the predictive value of the voltage criteria is cumulative. i.e. The more voltage criteria met, the greater the likelihood of LVH.

In the ECG above, the precordial leads do not meet the voltage criteria for LVH (arguably borderline, I admit, at 35mm).

Many clinicians are aware of the R and S wave criteria in the precordial (chest) leads, but this can be dependent on body habitus. The chest leads placed on a  tall, thin man, with little adipose tissue, are in close proximity to the heart so naturally, the waveform amplitude in the chest leads will be large.   The limb leads, being less affected by body habitus, are often more reliable in these individuals.  
Voltage criteria for LVH in V1-V6 alone, in a tall thin person, without other cause for concern, it not necessarily and indication for an ECHO. 

If a patient with LVH criteria on ECG is hypertensive, then arguably, an ECHO is only helpful if it will alter your threshold for treatment. If you plan to treat anyway, an ECHO is of dubious further value. 

Likewise, with an ECG suggestive of LVH in a normotensive person, an ECHO would only be indicated if a) Body habitus didn't explain the amplitude, or b) There was other signs/symptoms of concern (Possible HOCM? or Aortic Stenosis?)


Strain pattern
When LVH is associated with other pathology, such as hypertension or aortic stenosis, a 'strain pattern' is often seen:
  • ·      ST depression + flipped asymmetric T wave
  • ·      ST elevation + upright asymmetric T wave
  • ·      The strain pattern is greatest in the lead with the tallest/deepest QRS complex.  (seen in Lead 1 in example above).

Thank you.  :-)


HW/sept2012/#ecgclass


7 comments:

  1. Easy and good explained for student and postgraduate doctor

    ReplyDelete
  2. Excellent explaination

    ReplyDelete
  3. Interestingly, there is no one universally agreed criteria for diagnosis of LVH by ECG.
    -----------
    It is also often diagnosed "possible lvh" on ECG while it is not the case at all.( from a yahoo discussion )
    -----------
    I am 25 yrs old man with no heart pain or symtoms and while I did an ECG just for a medical certificate to join in a gym, I was observed with " possible lvh" and Now I am prescribed for another ECG and a cardiac visit. And after reading it I feel relaxed and hope that it would be very normal (the lv thickness )

    ReplyDelete
  4. I'm sorry to hear that. I hope the repeat check up is fine. If so, what a shame you've been put through all that unnecessary worry. This is a typical example of unecessary screening - a problem about which many doctors are becoming increasingly concerned. If your blood pressure was found to be high, then requesting an ECG may have been appropriate, but in the absence of any symptoms or signs, it has the potential to cause more harm than good.
    You may be interested to read more about this kind of thing at http://privatehealthscreen.org
    Good luck! Hope all goes well. H.

    ReplyDelete
  5. Whilst the specificity of ECG to predict LVH may be low, it is useful to pick up cases of genuine LVH (due to HCM, Fabry's, Aortic valve disease, long standing hypertension etc., remembering there is no absolute need to have a family history of HCM with a new diagnosis).
    I think obtaining a echocardiogram when there is a concern is no harm at all; it is a simple test with no radiation involved...

    ReplyDelete
  6. Thank you. I totally agree that 'when there is concern' an ECHO is a safe and reasonable non-invasive test. On the other hand, where there is no concern, no symptoms and inconclusive criteria for LVH, any medical investigation has the potential to cause more harm than good through psychological morbidity. As doctors we have a duty to bear this mind, and fully discuss the pros and cons of investigation, with the patient, in every case.

    ReplyDelete
  7. Yes precordial leads may not be the only criteria for LVH and we have to tak care of the HYPERTENSION & other factors and at times Echo is done as I gives more insight abour oher abnormalities like valvular defects////Thank u

    ReplyDelete