Wednesday, January 6, 2016

Chest pain in an elderly male.

An elderly male complained of chest pain.  Here is his ED ECG:
Inferiorly, there are Q-waves with minimal ST elevation and reciprocal ST depression in aVL.
There is also subtle ST elevation in V3 and some ST depression in V5 and V6
Is this a subtle inferior MI?  Subtle anterior MI?
See below.

















Notice there is pre-excitation (WPW).  The delta wave is negative in III and aVF (mimicking a Q-wave of MI).  It is easiest to see in I and aVL, where the PR interval is also short.  The PR interval is not short in every lead because the delta wave is not clearly visible in every lead.  Look at lead II for instance.

 Pre-excitation (an abnormality of depolarization) results in abnormal repolarization, often mimicking MI.

Whenever you see ST-T abnormalities (repolarization abnormalities), look to be certain that they are not simply a result of an abnormal QRS (depolarization abnormalities).  Abnormal ST-T may be primary (due to a pathology such as ischemia) or secondary to an abnormal QRS.

Clinical course:

The WPW was recognized and serial ECGs remained the same.  The patient ruled out for MI.

Here are several other examples of WPW mimicking MI:

WPW mimicking and obscuring acute MI



4 comments:

  1. Hello Dr. Smith, I have a couple of questions:
    1.The P wave in DII looks like a P mitrale (LAA) and seems close to 0.12 sec, in lead DI as well. In this case the PR is over 0.12 due to just the P wave. How would you define a short PR in this case ( you said the PR is short in DI)?
    2. In V3, is the wave between the P and the QRS complex a delta wave?

    ReplyDelete
    Replies
    1. Adrian,
      1. that is a delta wave that is nearly isoelectric and just squiggles: not positive, not negative. Makes it look like a regular PR interval. But it is not.
      2. yes!
      Steve

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  2. 1.Are you reffering to the P wave in DII ? because the P wave morphology in V1 is also suggestive of LAA. And if the P wave is prolonged( theoretical situation) how would define a short PR in WPW( because the PR segment would be short but the P wave would be prolonged resulting in a "normal" looking PR interval-lenghtwise)
    2. Is there a reason why the delta wave is separated from the R wave?
    (I hope these questions are pertinent)

    ReplyDelete
    Replies
    1. In DII, the delta wave begins immediately at the end of the P-wave (which may, indeed, have LAA, but is not important here). The entire PR interval is exactly the length of the P-wave and is < 120 ms. Of course, in WPW, the PR interval need not be short! In many cases, there is "concealed conduction" in which you cannot even see a delta wave (there is no pre-excitation). In others, the only reason you see the delta wave is that there is first degree AV block which gives enough time for the pre-excitation to show itself. Too complicated to describe here.

      Delete

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