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Wednesday, January 4, 2012

Just a little burning... and a ton of bricks.

To get back in the flow after the holidays, I got a small one. No big mysteries either - it's an MI, and there's some atrial fibrillation. But it's a nice example of ALS gettin 'er done. Thanks to Tyler, from AMR, for taking care of this lady.

So this 60-ish woman with an "extensive cardiac history" calls 911 for a little burning in her epigastrium, and a feeling of palpitations. Upon further questioning, she admits that she also feels like she has a "ton of bricks" on her chest.
First ECG:

Okay, got some work to do here. A bit of diltizem, get the aspirin on board, and a little nitro. This all brings down the load her chest to just a few bricks. Time for another ECG!
Hey, where did the  *** ACUTE MI SUSPECTED *** label go? To me, the ECGs look pretty similar, but some element in the interpretation algorithm - the depression in aVL? The STE in aVF? - changed enough such that the computer didn't want to make the call. Now, on a gut level, the ST segments in the inferior leads "feel" the same as before, but it sure looks like we have lost the strict "1mm of elevation" criteria that's been drilled into our heads.


We got an ECG in the ED which looked basically the same as the EMS tracing.
 Hmmm.

This is a tough one. It looks like we just fixed a potential cath lab patient, but you should be dubious. You can change a lot of ST depression with NTG and diltiazem, maybe even re-flip some inverted T-waves. But not too many things (at least until we get tenectaplase in the protocols) "fix" ST elevations.

So, the answer to confusion about new ECGs is usually an old ECG. Tough to do at 75 mph, but somewhat easier in room 5.

Our lady's ECG from the recent past:
About 4 months ago

Tyler and I compared the two, and agreed on our interpretation - activate the cath lab. After a brief conversation with one of the great cardiologists at Cardiac Specialists, our patient was whisked up to the cath lab.

Good thing too. Turns out she had thrombosed a stent that had been placed some years back in her RCA. Real bad luck for her, despite being on Coumadin for her a fib, as well as aspirin!


So what is the larger point here? 

If the paramedic had just looked at the rhythm strip and (correctly) treated the rapid a fib, the less-prominent ST elevations might not have been noticed in the field. Heck, it might have slipped past me in the ED! On the other hand, a second ECG may have shown growing elevations - you never know. That's why in some regions EMS is now obtaining up to 3 ECGs in the field as a matter of protocol, and they are catching more STEMIs as a result.

By the way, when I talked to the cardiologist during the cath report, he had one request - that we send the patient up with the prehospital ECGs!

4 comments:

  1. Interesting case... to me, a few points:

    - in the setting of tachycardia, the accuracy of the 12 lead algorithm greatly diminishes.

    - both ST depression AND ST elevation may resolve with treatments, such as ASA and NTG, which can reperfuse the artery, or just spontaneous reperfusion of the artery can resolve the segments. That is why it is so important to obtain a 12 lead as soon as practicable, before treatments have a chance to change those segments.
    -It is also a reason pre-hospital ECG's are so important, because upon arrival at the hospital, elevated ST segments may have resolved to the point that the only real evidence of the occlusion exist only on the pre-hosptial ECG.

    -DaveB

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  2. Just checked out Smith's case - glad I didn't read that before that patient rolled in!

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  3. I wouldn't have treated the rate because it's not particular fast and speed is harder to determine when the rate is irregular. At that rate, the speed is more likely a reaction to dyspnea, hypoxia, and of course pain. Fixing those underlying problems is a better course of action, at least in my mind.

    Since vital signs and respiratory status aren't in the story, it's harder to tell what's going on.

    Based on 12 Leads I and II, I'd have called a STEMI alert. It's not borderline to me at all. Again, in EMS we mostly temporize and the O2, ASA, and NTG might have relieved the symptoms, but they didn't correct the root cause.

    Did the crew give any pain relief such as Morphine?

    Good case and good work by the medics.

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