MI without 12 lead changes?

[mediccjh]

Hence the reason we perform "serial" ECG's. As well, ever seen non "q" wave AMI's? In fact one of the old test questions from ACLS was " a normal XII lead, excludes an AMI?"..

Like Doc described not all AMI's have ECG changes.

R/r 911

You mean when you didn't have to hold hands to pass? I long for those days.........

[Mateo_1387]

The Non-STEMI is detected through elevation in cardiac enzymes like troponin.

If this scenario repeates itself reply to your medic "Might be a Non-STEMI, but I can only call it unstable angina till the blood work comes back".

Even Angina can cause false positive in the bloodwork. Troponin can be released due to ischemia caused by angina.

[fiznat]

My instructor explained it as this : It takes about 1 hour for cardiac muscle to be injured and 6 for it to die.

I dont think one can really make this kind of generalization. How quickly the tissue dies is a direct result between the ratio of supply and demand. If the patient has a small blockage and a huge demand, that tissue is going to die just as fast as if he has very little demand and a total occlusion. Saying a heart will "last" a certain period of time without knowledge of a whole host of other factors is incorrect at best...

That said, I too was surprised to find out how low the sensitivity was for 12 leads... it really is our most powerful single diagnostic tool in the pre-hospital field, and it hurts to find out that even with the best we can give them, we still really have no idea. I guess this is why they try and teach us to be thorough with our patient assessments, and to consider the "whole picture" rather than getting tunneled in. The ECG alone does not rule in, and it does not rule out.

[Kaisu]

I dont think one can really make this kind of generalization. How quickly the tissue dies is a direct result between the ratio of supply and demand. If the patient has a small blockage and a huge demand, that tissue is going to die just as fast as if he has very little demand and a total occlusion. Saying a heart will "last" a certain period of time without knowledge of a whole host of other factors is incorrect at best...

Makes sense to me. I think the "dumbed down" version was just for openers. We are not finished the cardiology section yet and this instructor will sketch out the broad bones of a topic first, then fine tune it in subsequent lessons. That way we are always adding on to an existing knowledge base instead of trying to digest it all in one foul swoop. I really appreciate that way of learning and I certainly did not mean to imply that this was all there was to it.

[Doczilla]

On a serious note, Doc have you had any experience using ultrasound or CT/MRI for suspected MI's? Some of our docs have suggested they should be considered.

I have never ultrasounded a coronary artery before. 2D cardiac echo is pretty much a standard here prior to discharge after ACS rule-out. We don't have a cardiac observation unit, so our chest pain patients get admitted and get the echo with the stress test.

CT coronary angiography is gaining fairly wide acceptance. The recommendations are now coming out supporting its use in acute coronary syndromes. We haven't gotten up to speed on it yet here, but it seems like just a matter of time.

Cardiac MRI/MRA is pretty slick according to the radiologists. We don't have the technology here. I don't know that there is a recommendation yet on it's utility for acute coronary syndromes, and I don't know that we have yet defined it. For that matter, getting a stat MRI here takes an act of Congress. You can pretty much only get it for cauda equina syndrome.

'zilla

[Dustdevil]

In short she said (paraphrased) "I believe he was having an MI and it just hasn't shown up on he 12 lead yet, you do know and MI doesn't necessarily show up right?"

Heh... I'm waiting for the punch line, where she says, "And you would have known that if you had worked as an EMT-B for five years!"