Wednesday, January 28, 2015

Ultrasound Before ECG for Chest pain? Whoever gets there first. Use of Speckle Tracking.

A male in his mid 30s with no cardiac history but some cardiac risk factors had onset of chest pain and arrived in the ED within 30 minutes of onset.

He was brought directly to a room, where our Hennepin ED ultrasound guru Dr. Robert Reardon performed a bedside cardiac ultrasound immediately, before an ECG could be recorded.

Drs. Reardon and Scott Joing of Hennepin are Editors of Ma and Mateer's Ultrasound Textbook and, along with Andrew Laudenbach (also of Hennepin), authors of its cardiac ultrasound chapter.

Here is the initial parasternal short axis echo:


Dr. Reardon read this as an inferior wall motion abnormality.  The most obvious finding to me is the asymmetry of contraction

This circles the area that Dr. Reardon pointed out to me as having a wall motion abnormality.  It is very subtle.  I can barely see it even after it is pointed out.  You will see more obvious images below using Speckle Tracking.

An ECG was immediately recorded.  I was there with Dr. Reardon to read it.  Its findings are (to me) much more obvious:
There is subtle ST elevation in III, but also in II and aVF.  Most importantly, there is clear reciprocal ST depression in aVL.  This is all but diagnostic of inferior MI (but not STEMI because there is not enough ST elevation for STEMI)


A right sided ECG was recorded:
V1-V6 are really V1R - V6R.  There is clearly greater than 0.5 mm of ST elevation in V4R.  
This is nearly diagnostic of Right Ventricular injury

His blood pressure was good and there was no evidence of RV infarct physiology.

The patients pain was unrelenting.  The diagnosis was clear.  The cath lab was activated in the middle of the night just minutes after the patient arrived.

Dr. Reardon proceeded to record some images using "Speckle Tracking," in which, after telling the computer where the endocardium is with a few markers, it automatically tracks wall motion of all the sectors, and even graphs their motion (on the right).

Here is a parasternal short axis:

5 of 6 segments contract, thicken, and shorten.  The sixth ("inf") on the lower left, does not do so.  The graph at the right shows the degree of wall motion of each of the 6 segments.  The top one, which has the least motion, is the line representing that inferior segment.

Here is a second parasternal short axis:


Here is a still frame:

The lavender line shows how little wall motion there is at the inferior wall

Here is an apical 2 chamber view:


The segment on the lower left is the inferior wall, in purple, and you can see how it has no motion.  On the graph, it is represented by the purple line at the top (it is at the top because it has so little wall motion)
Here is a still frame of the above

Case continued

While waiting for the cath team, 2 more ECGs were recorded, with no evolution.

The patient was taken to the cath lab and had a 100% occlusion of the mid RCA.  There were 4 Right ventricular marginal branches BEFORE the occlusion.  So the right sided ST elevation is unexplained.

Also, there were good left to right collaterals so that only a small portion of the inferior wall was completely ischemic.

This accounts for the subtle ECG findings and the lack of evolution.

The highest troponin I was 13 ng/mL.

Here is the post cath ECG:
All ST elevation is resolved.  There are subtle inferior Q-waves of infarction.

6 hours later, another ECG was recorded:
Now there is T-wave inversion in III, with well formed pathologic Q-waves of infarction.





8 comments:

  1. Steve -

    Great case! I think I could "sell" the echo to cardiology a whole lot more easily than the ECG.

    One trick I was shown by cards: Try covering up 1/2 of the echo with your hand. In your example, first cover the bottom half, and note the full thickening. When I cover the top half of the image, however, the lack of contraction is highlighted quite clearly. Using this method, the inferior WMA pops out at me far more clearly than the ECG changes!

    Brooks

    ReplyDelete
    Replies
    1. Brooks, I tried your technique and like it!
      Thanks,
      Steve

      Delete
    2. I learned that same trick just last week! I like it as well.

      Delete
  2. Hi Dr Smith
    Thank you for good case .
    In the 1st ECG, there are subtle ST depression on V5-6 , which is resolved after
    treatment. Is this due to reciprocal change of
    rt ventricular infarction? In the rt ventricle,
    is it impossible for speckle tracking?

    ReplyDelete
    Replies
    1. youhong,
      Good question! The ST depression probably is due to RV infarct. I have never used Speckle Tracking on the RV and I'm not sure how well it would work. The RV has fewer segments to view for segmental WMA, so I think it would be more difficult. It is more often seen as global dysfunction or not. But I am no expert on that.
      Steve Smith

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  3. Great pearl by Brooks! So I thought of going one step further = I used 2 hands to look separately at each quadrant (blocking out the other 3 quadrants as I looked each time) — and lo & behold, that subtle inferior wall motion abnormality that I initially missed was now much more evident when all I was doing was looking at a single quadrant at a time for LV motion. Support that this finding is real is clear from assessment of the 1st ECG. I’d add to the points made by Dr. Smith that lead I on the 1st ECG shows subtle-but-real ST depression — and that the small terminal T wave positivity that we see in lead aVL on the 1st tracing is a mirror image of the suggested terminal T wave negativity in lead III. THANKS for presenting!

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  4. Do these new Q waves in inferior lead indicate a failed PCI ...... Anatomically Flow restored but EF falls after PCI ?

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    Replies
    1. Rajiv, I do not think so. The best sign of failed reperfusion is absence of ST resolution and persistence of an upright T-wave. There was good reperfusion, but it happened after enough infarction to result in Q waves.
      Steve

      Delete

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