Interesting ECG that got me....

[Christopher]

I think you did fine playing it safe, no one will ever come after you for playing it safe. If it was me personally, I would of transmitted the ekg and discussed it with the physician as to if he wanted to activate or not.

We've got a pretty liberal activation policy in my area, but excessive false positives will get you in trouble and probably should. Our area does not consider LBBB w/o primary changes or LVH to be reasonable activations. Systems with paramedic activation need to make sure they're not just activating to cover their butt. (nb: this comment is not directed at this ECG in particular)

Borderline cases are best called in as, "we've got X and Y, which any other day of the week we'd call a STEMI, but because of Z we don't meet criteria. We think this guy needs to an ACS workup ASAP upon arrival, we'll advise if his ECG trends to meeting criteria."

 

[FLdoc2011]

I think the term you are looking for is "staticus hispanicus" or "hispanic panic."

Had the exact same thought/joke in my mind...

 

[KellyBracket]

Ran a call today that I kinda felt like I jumped the gun and misinterpreted the ECG....

Quick trip across the street where the STEMI protocol was cancelled pretty quickly.

If you were truly "across the street," then you rock.

It seems that all too often we hear the explanation "we were right around the corner," when EMS shows up with some syncopal octogenarian, but no ECG. I'm starting to think that the population density within a one-block radius of our ED approaches that of Hong Kong!

On another note - this is a fairly common STEMI mimic, but it routinely gets called as *** ACUTE MI *** by the computer. Although people claim that the computer is very specific for STEMI, I am dubious. Christopher, I'm sure you have some equipment-specific insights!

 

[Brandon O]

If you were truly "across the street," then you rock.

It seems that all too often we hear the explanation "we were right around the corner," when EMS shows up with some syncopal octogenarian, but no ECG.

To me, one step outside the ED door is a vast distance from one step inside, as far as certain time-to-care issues and decisions are concerned. It's like entering Narnia.

On another note - this is a fairly common STEMI mimic, but it routinely gets called as *** ACUTE MI *** by the computer. Although people claim that the computer is very specific for STEMI, I am dubious. Christopher, I'm sure you have some equipment-specific insights!

The Marquette algorithm was highly specific. All of the newer algorithms, and the Philips algorithm too, seem to be less so (presumably in the pursuit of greater sensitivity). We must adjust.

 

[systemet]

I try to always fold the monitor interpretation over and not look at it until after I've done it myself and I had decided to activate our STEMI protocol before I read the monitor interp, which had interpreted it as ***Acute MI***.

(snip...)

After my giant rant, did I jump the gun activating our STEMI protocol on this patient? I'll admit, I didn't have a long DDx list (MI, AAA/Dissecting TAA, Tamponade as my zebra).

As someone else said, I think it's really hard to ignore the monitor when it spits out "ACUTE MI SUSPECTED", and you want to bias any errors in the favour of the patient. Better to upset the cathlab than miss the MI.

That being said, I think there's been a lot of good discussion about ST proportionality and T wave symmetry. The downsloping ST depression in the lateral leads looks very LV strain'y.

For what it's worth, I got myself caught calling a STEMI on a RBBB c/ RAD / RVH the other day. I think these type I / false positive errors are much better for the patient than a type II / false negative. We're all human.

 

[KellyBracket]

The Marquette algorithm was highly specific. All of the newer algorithms, and the Philips algorithm too, seem to be less so (presumably in the pursuit of greater sensitivity). We must adjust.

Wish we had some numbers to back up that impression, as I obviously agree!

 

[Summit]

I learned in this thread. So where to read more on some of the proportionality discussion? A particular 12 lead book you all recommend?

 

[mycrofft]

Speak to me not of algorithms...

The machine in the north exam rm said I had occasional PVC. The one on the south said atrial fib. Updated software maybe. Guess which was right?
==========
I'm encouraged to hear no one got distracted by the seizureform activity after falling out. Seen that in lots of vaso-vagals post immunization with NO cardiac issues.
=========
OP quote:
"STEMI protocol activation
Bilateral 20s, tried to draw labs but I was tied up doing things and my partner didn't leave the TQ in place so she couldn't get them to draw.
324 mg aspirin.
NTG SL x2 pain down to 5/10, no EG changes pre/post NTG, no notable changes in her HR or BP.
Quick trip across the street where the STEMI protocol was cancelled pretty quickly. "

Drawing labs when you are a couple hundred feet away from a hospital? I'm assuming you are throwing that in to make us think about what would be occurring if you were fifty miles out as well.

 

[Christopher]

Drawing labs when you are a couple hundred feet away from a hospital? I'm assuming you are throwing that in to make us think about what would be occurring if you were fifty miles out as well.

We draw them because when we activate a STEMI we go right to the cath suite and hand off our labs on the way. Only reason for the hospital to draw them is if we have to pit stop in the ED or if we couldn't get access and they do it in the cath suite.

 

[Christopher]

On another note - this is a fairly common STEMI mimic, but it routinely gets called as *** ACUTE MI *** by the computer. Although people claim that the computer is very specific for STEMI, I am dubious. Christopher, I'm sure you have some equipment-specific insights!

I don't have the DXL guide handy, but my guess is it went something like this:

• Gender and age make STJ measurements in V1-V2 back to "isoelectric is normal"
• Broad QS complexes in V1-V3 recognized as Anteroseptal Infarct
• In the absence of >1.5mm STE in V1, I believe you'd have seen "age undetermined" rather than >>> ACUTE MI <<<
• LVH disabling AWMI detection probably occurs with r-waves present

I didn't think Marquette called LVH STEMI quite that often, and I know the Inovise on our Zoll X-Series (when it's not complaining about data quality) avoids STEMI w/ LVH, but I can't say definitively whether the DXL or Glasgow make an "early out".

I've seen Marquette get an inferior STEMI w/ LVH correct before, so I dunno. I think you can teach Paramedics how to weed out cases which fool the monitor and it would be best to leave the sensitivity a bit higher on the devices and improve the specificities on the people.

 

[truetiger]

Is it just me or does the Zoll X series just take terrible 12 leads? More often than not it will take forever to pick up a signal in 12 lead mode. Always seems like I'm waiting on a lead or two. Most of the 12 leads seem to be substandard quality as compared with our last Zoll monitor or the Lifepak 12.

 

[Christopher]

I learned in this thread. So where to read more on some of the proportionality discussion? A particular 12 lead book you all recommend?

It is pretty simple really, just perhaps not put to you in this way:

The amplitudes of the electricity in the heart as seen on the ECG are roughly proportional to the myocardium involved. (and what electrode pair you're using)

This is why the P-waves of the atria are small and the R-waves of the ventricles are large.

Taking this one step further, if you get an enlarged atria or ventricle you get an increased amplitude in their corresponding complexes.

This applies to more than just the amplitudes of depolarization.

If you think about it, if X amount of myocardium depolarizes, X amount is going to repolarize. So, if the amplitude of depolarization is large, the amplitude of repolarization will be large as well.

What separates repolarization from depolarization is how it occurs. Depolarization follows a wavefront and moves rather quickly. This is why you mostly get sharp upstrokes and downstrokes in your QRS complexes.

Whereas repolarization occurs on an individual basis and isn't homogenous. This is why your T-waves are broad and asymmetric.

So back to proportionality.

If we expect big depolarizations to have big repolarizations, certain features of repolarization are bound to be exaggerated. In this case, the ST-elevation found in LVH or LBBB will look exaggerated. Both of these are processes which alter depolarization, thus we expect to see this exaggeration.

Simply put, altered depolarization = altered repolarization. Tack onto that a constant multiplier for the amount of myocardium involved and you've got yourself an explanation for proportionality.

So why do we use absolute millimeter criteria?

STEMI's don't care about our criteria, and you can probably guess the primary changes of ACS are a continuous variable rather than a discrete one. Tiny depolarizations will have a tiny primary change during ACS, and aVL is a great example.

But, when they were designing and defining cut-offs for "normal" STJ measurements during the trials of Thrombolytics for MI's they needed to arrive at a measure that was both Sensitive and Specific for myocardial infarction. Thus you end up with the arbitrary &gt;1mm STE in &ge;2 contiguous leads and later modifications to make it &ge;2mm STE in the right precordials.

I hope that helps with your understanding of proportionality!

 

[Brandon O]

Well, Mr. Watford, that's about the best of proportionality explanation I've heard.

 

[Sublime]

It is pretty simple really, just perhaps not put to you in this way:

The amplitudes of the electricity in the heart as seen on the ECG are roughly proportional to the myocardium involved. (and what electrode pair you're using)

This is why the P-waves of the atria are small and the R-waves of the ventricles are large.

Taking this one step further, if you get an enlarged atria or ventricle you get an increased amplitude in their corresponding complexes.

This applies to more than just the amplitudes of depolarization.

If you think about it, if X amount of myocardium depolarizes, X amount is going to repolarize. So, if the amplitude of depolarization is large, the amplitude of repolarization will be large as well.

What separates repolarization from depolarization is how it occurs. Depolarization follows a wavefront and moves rather quickly. This is why you mostly get sharp upstrokes and downstrokes in your QRS complexes.

Whereas repolarization occurs on an individual basis and isn't homogenous. This is why your T-waves are broad and asymmetric.

So back to proportionality.

If we expect big depolarizations to have big repolarizations, certain features of repolarization are bound to be exaggerated. In this case, the ST-elevation found in LVH or LBBB will look exaggerated. Both of these are processes which alter depolarization, thus we expect to see this exaggeration.

Simply put, altered depolarization = altered repolarization. Tack onto that a constant multiplier for the amount of myocardium involved and you've got yourself an explanation for proportionality.

So why do we use absolute millimeter criteria?

STEMI's don't care about our criteria, and you can probably guess the primary changes of ACS are a continuous variable rather than a discrete one. Tiny depolarizations will have a tiny primary change during ACS, and aVL is a great example.

But, when they were designing and defining cut-offs for "normal" STJ measurements during the trials of Thrombolytics for MI's they needed to arrive at a measure that was both Sensitive and Specific for myocardial infarction. Thus you end up with the arbitrary >1mm STE in ≥2 contiguous leads and later modifications to make it ≥2mm STE in the right precordials.

I hope that helps with your understanding of proportionality!

Yup.. you're awesome.

 

[BandageBrigade]

Unfortunately we cannot transmit ECGs. Well, I'm sure the MRx is capable but we don't have the system in place at the ERs to receive them

All you need is a blue tooth capable phone and the ER fax number.

 

[mycrofft]

Is it just me or does the Zoll X series just take terrible 12 leads? More often than not it will take forever to pick up a signal in 12 lead mode. Always seems like I'm waiting on a lead or two. Most of the 12 leads seem to be substandard quality as compared with our last Zoll monitor or the Lifepak 12.

Have your wiring harness checked or swap it between two same-brand machines which work differently (one is better). A faulty set of wires will cause delay in a lead or two before it goes out entirely. Is it the same leads over and over?

 

[mycrofft]

We draw them because when we activate a STEMI we go right to the cath suite and hand off our labs on the way. Only reason for the hospital to draw them is if we have to pit stop in the ED or if we couldn't get access and they do it in the cath suite.

Good deal as long as nothing needing STAT hospital juju happens while trying to draw labs " across the street". Has a strong potential for a Murphy's Law encounter, but good they will work as closely as that!

 

[Handsome Robb]

OP quote:
"STEMI protocol activation
Bilateral 20s, tried to draw labs but I was tied up doing things and my partner didn't leave the TQ in place so she couldn't get them to draw.
324 mg aspirin.
NTG SL x2 pain down to 5/10, no EG changes pre/post NTG, no notable changes in her HR or BP.
Quick trip across the street where the STEMI protocol was cancelled pretty quickly. "

Drawing labs when you are a couple hundred feet away from a hospital? I'm assuming you are throwing that in to make us think about what would be occurring if you were fifty miles out as well.

Yes, we were across the street. I could have thrown a rock threw the window of the helicopter on the ground pad. Well, maybe not but I definitely could come close. Our transport milage was 0.1.

We draw labs on STEMI activations that we take to a certain facility because, like Christopher said in the quote below, we generally meet a cardiologist or ER Doc at the door they look at our 12-leads and then send us on our way to the cath lab or cancel it. We do stop in the ER if the lab isn't ready or they're all being used.

We draw them because when we activate a STEMI we go right to the cath suite and hand off our labs on the way. Only reason for the hospital to draw them is if we have to pit stop in the ED or if we couldn't get access and they do it in the cath suite.

Quoted for my answer above.

Good deal as long as nothing needing STAT hospital juju happens while trying to draw labs " across the street". Has a strong potential for a Murphy's Law encounter, but good they will work as closely as that!

Agreed, but even being close to the hospital there are still things that need to get done before we get there. While I'm working on getting asa on board, activating the cath lab, getting her on O2 since the protocol gods want it my partner is dropping a line and pulling labs off it, generally a pretty quick task except she may or may not have taken the TQ off so it wouldn't draw and I was busy and didn't have time to help her.


I've learned a lot from this thread, thank you! I've got some questions but I'm too tired right now from riding all day to comprehend anything complex right now.

 

[truetiger]

Have your wiring harness checked or swap it between two same-brand machines which work differently (one is better). A faulty set of wires will cause delay in a lead or two before it goes out entirely. Is it the same leads over and over?

Not the same leads, and it does it on pretty much all of the Zoll's. They are not even a year old yet.

 

[the_negro_puppy]

02 for STEMI is verboten here unless they are de-saturated