What it looks like: inferior STEMI

No mysteries here today – this is an inferior STEMI! But I thought that prehospital provider might like to see what happens “on the inside” during an MI.

The Case:

A 60-something female had a few days of feeling not quite right, so she did some Googling, and she began to worry about a heart attack. Therefore, when she acutely developed neck and jaw pain, she figured that her self-diagnosing was probably correct, and she called 911 without delay. Time from symptom onset to first medical contact (FMC) was about 30 minutes.

The ECGs

EMS captured an initial 12-lead:

ST elevation in III and aVF, reciprocal ST depression in aVL. Again, NOT a mystery.

ST elevation in III and aVF, reciprocal ST depression in aVL. Again, NOT a mystery.

The medics immediately called for cath lab activation. Because of the off-hours presentation, the patient was evaluated in the ED while the team assembled. A second ECG was obtained:

Muy_obvio_ED

No changes – still bad.

Since the patient was comfortable, and her condition was stable, we did an echocardiogram for education’s sake.

The Echos:

When a portion of the heart is ischemic, it doesn’t move very well. It’s like an area of the heart is paralyzed, and the echocardiogram can be as good as the ECG in showing ACS, and sometimes it’s better!

Let’s take a look at two views of the heart moving. First,imagine you chopped the heart in two, like a loaf of bread. Since the left ventricle is shaped like a hollow tube, you would be looking at a ring of myocardium. This is the short-axis view:

screenshot898

From my friends at Yale http://www.yale.edu/imaging/echo_atlas/views/short_axis_lv.html

The right coronary supplies the muscles from about “6 o’clock” to “9 o’clock,” also supplying blood to the posterior papillary muscle marked in the picture. Our patient’s short-axis view showed:

Watch this for a while, and you might note that the area from 6 to 9 o’clock isn’t moving that great. Let me highlight that part of the image:

Red arrows = not contracting well

Red arrows = not contracting well

Let’s take another look at the heart. This time, instead of slicing the heart like a loaf of bread, we’re slicing it like a bagel! This is called the apical 4-chamber view, since the apex of the heart is at the top, and we see all 4 chambers of the heart:

Again, from Yale http://www.yale.edu/imaging/echo_atlas/views/four_chamber.html

Again, from Yale
http://www.yale.edu/imaging/echo_atlas/views/four_chamber.html

The RCA supplies the wall in between the LV and the RV, while other arteries supply the apex. Our patient:

If you look at the septum, you see it isn’t contracting when the other side of the LV is. Let me highlight that area with red arrows:

screenshot891

Red arrows = actually moving the WRONG way during systole.

 Follow-up:

Our patient had such a brief interval from FMC to balloon inflation that her troponin never turned positive. Nonetheless, we have both ECG and echo evidence of a large potential infarct that was treated before it could do serious damage.

2 Comments

  • Ken Grauer says:

    SUPERB teaching post Brooks! For the uninitiated – Echos are challenging to interpret. By adding anatomic and marked still-frame shots – together with clinical and ECG evidence – you have made it easy to understand the abnormalities seen here. THANK YOU for posting – 🙂

  • Matt Templeman says:

    This is really interesting from my Pre-Hospital point of view. Thanks for posting in such an informative way!

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