Why didnt my medic want to do a 12 lead? (3 lead attached)

[fiznat]

He said that "its probably old damage, not anything new."

I realize this is only a 3 lead and therefore not diagnostic for STEMI, but c'omon, right? Its pretty obvious-- even to a medic student such as myself. I felt that the medic should have taken this as a hint and done at least a 12 lead to see whats really going on. ...Also I understand that old infarct is usually seen as ST depression, not elevation?

We were called to this patient for a fall out of bed (less than 2 feet). Hes at his baseline mental status per the SNF staff, and has no complaints whatsoever: no SOB, no CP, no pain s/p fall, nothing. Hes got really poor skin turgor and the BP is 90/50. HR is 46 and irregular (hx of a-fib, which is visible on the strip). Resp rate is 18. The facility was unable to tell us about any of his other meds or hx (I know, I know)- apparantly their paperwork is not in order.

I'd do the 12 lead, wouldnt you? Anything you see here that would make you NOT do it?

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[southerndoc]

Anything you see here that would make you NOT do it?

A 30 second transport time?

 

[DropkickMurphy]

Either a BBB or ST elevation, so if I were the medical director, someone would have *cue Ricky Ricardo voice* 'splainin' to do......

Is it just me, or does anyone else see P waves in front of those complexes......maybe I'm just seeing things.....because it looks like a 2nd degree block sort of......but then the patient has a history of AFib after all.....

 

[fiznat]

Nah its most definitely A-Fib... its more obvious when you look at the whole strip.

Transport time was about 5 minutes. Plenty of time.

 

[DropkickMurphy]

OK....but then again I've been awake for 25 hrs......my brain is starting to lose higher function.....

 

[Squad51]

He said that "its probably old damage, not anything new."

I realize this is only a 3 lead and therefore not diagnostic for STEMI, but c'omon, right? Its pretty obvious-- even to a medic student such as myself. I felt that the medic should have taken this as a hint and done at least a 12 lead to see whats really going on. ...Also I understand that old infarct is usually seen as ST depression, not elevation?

I'd do the 12 lead, wouldnt you? Anything you see here that would make you NOT do it?

There is no reason NOT to do it and given things as you describe, I might have... but, you do need to understand that a monitor, not set to a "12 lead" or "diagnostic" setting, is ABSOLUTELY WORTHLESS for looking at the ST segment. In a monitor setting, a ECG looks at the ~0.5 to ~40 Htz band (some use 1 to 30 Htz), because this is where the QRS "lives". By keeping the sampled frequency limited, interference is reduced and the most important part of the cycle (the QRS) is seen. The problem is that the ST segment "lives" just above 0.05 Htz, far too low for monitor frequencies to accurately detect.

In short, I would have probably done a 12 lead based on the story you told, but that strip would not have influenced me at all...

 

[viostorm]

He said that "its probably old damage, not anything new."

I realize this is only a 3 lead and therefore not diagnostic for STEMI, but c'omon, right? Its pretty obvious-- even to a medic student such as myself. I felt that the medic should have taken this as a hint and done at least a 12 lead to see whats really going on. ...Also I understand that old infarct is usually seen as ST depression, not elevation?

First, ST elevation is not significant for AMI in presence of bundle branch, which this patient almost certainly had. (To be complete because some of the ED docs will almost certainly call me out if you are well trained/experienced you can look at LBB/LVH with st-elevation and determine if it is the appropriate change you would expect in LBB/LVH variant versus pathological infarct)

ST elevation analysis is not useful for predicting AMI in cases of:

* Ventriculary hypertrophy
* Aneurism
* LBB
* Pericarditis
* Benign early repolarization
* Medications (digoxin and other meds that cause ST segment changes)

So, in these cases (your patient) ST segement analysis of the 12-lead is meaningless for predicting AMI. So, if you see LVH, you don't even have to look for AMI on your strip, because ST segment analysis is not helpful.

I'd do the 12 lead, wouldnt you? Anything you see here that would make you NOT do it?

This is a loaded question ... you can run a 12-lead on anyone and justify it. It is so non-invasive, cheap, safe, there really are few limitations to the test.

A better question is "When is a 12-lead indicated PREHOSPITALLY?"

The purpose of 12-lead prehospitally is to identify patients for reperfusion therapy. 12-leads have been shown to reduce door/drug or door/balloon time in several studies.

Indications for 12-lead:

1) CP/anginal equivalents in the hemodynamically stable patient

2) V-Tach patients prior to cardioversion so that a Cardiologist can potentially determine if it was VT or SVT w/ abberancy

12-lead is not indicated prehospitally in hemodynamically unstable patients or patients with significant dysrhytmias.

So back to your patient, because the patient had underlying bundle branch block, the 12-lead would have not helped identify the patient as someine in urgent need for reperfusion therapy because ST segement analysis is useless in BBB. The analysis would have said "wow, he has a bundle, now we have to run some tests to see if he is having an AMI" The same information can be gathered from the 3-lead.

But the big picture, even at the paramedic level, medicine is an art not a science and you have to be able to tolerate the fact people will treat patients in a manner you disagree with, and that is OK. It is even worse at the physician level.

So don't get all bent out of shape because he didn't run a 12-lead.

I think you both have arguments for either running it or not.

 

[viostorm]

Also I understand that old infarct is usually seen as ST depression, not elevation?

Old infarct is usually identified as pathological q-waves on the ECG.

The medic is probably right though, his underlying bundle branch block was probably an old unrecognized infarct.

Old infarct doesn't have anything to do with "ST segment depression"

People say that "depression" is suggestive of ischemia, but my personal opinion is this is very sketchy and probably not well validated.

You also have to remember, depression in a lead on one side of the heart means elevation in a lead on the opposite side of the heart, so I really don't know where this "depression = ischemia" ever originated. This is where reciprocal changes come from. That being said, digoxin usually only causes depression which is weird electrically.

I have sat in the cath lab and watched patients receive heart caths and the ST segments elevates in front of your eyes as the vessel is occluded during stenting, but I have never seen if flip from depression to elevation and vice versa. Usually it is only elevation appropriate for the particular infarct.

 

[12R34Y]

I have to disagree that BBB makes looking at a 12-lead useless.

There are criteria for determining if ST elevation are likely pathological in BBB and LVH.

ST elevation greater than 5mm, concordance of the Twaves with QRS, change from previous EKG (even with BBB).

You can't just say "oh, its a BBB, the 12-lead is useless."

There are other criteria that are helpful.

This is a prehospital misconception that I was guilty of back in my medic days as well. I always thought that BBB meant "who cares about ST segment".

later

 

[viostorm]

I have to disagree that BBB makes looking at a 12-lead useless.

There are criteria for determining if ST elevation are likely pathological in BBB and LVH.

ST elevation greater than 5mm, concordance of the Twaves with QRS, change from previous EKG (even with BBB).

You can't just say "oh, its a BBB, the 12-lead is useless."

There are other criteria that are helpful.

This is a prehospital misconception that I was guilty of back in my medic days as well. I always thought that BBB meant "who cares about ST segment".

later

Agreed ... I guess I was trying to put a disclaimer in that in presence of these STEMI "mimickers" 12-lead ECG interpretation becomes *complicated*

But don't you think Cards would have been pissed had the ED physician ordered a consult based on a guy with no CP and only underlying bundle and the reason they are at the hospital was he fell out of bed?

I can't imagine any cards fellow would rush this guy to the cath lab?

 

[fiznat]

viostorm your knowledge is obviously much more in depth than mine, however I have to ask: if a 3 lead is usless for diagnosing ST elevation, isnt it equally useless in diagnosing bundle branch block? Also, I understand the various conditions where ST elevation loses it's diagnostic value, however without a good history I dont see how can we be sure at all about whether this presentation is old, new, or part of some other pathology. Even if it really is a BBB, we dont know if it is new or not-- so once again, 12 lead?

The crux of the question is whether the 3 lead should suggest that a 12 lead is necessary. Is the 3 lead ST segment truly THAT worthless, as Squad51 said, to the point where it isnt even worth looking at? ...Or does that elevation there raise some suspicion that would suggest further testing is necessary?

Ya got me on the whole ST elevation/ST depression/Q wave thing. I'm still learnin.

I'm not all bent out of shape because my partner didnt run a 12 lead, I'm simply interested in asking WHY he didnt run it. I'm a student and I love learning about this stuff- simple as that.

 

[viostorm]

viostorm your knowledge is obviously much more in depth than mine, however I have to ask: if a 3 lead is usless for diagnosing ST elevation, isnt it equally useless in diagnosing bundle branch block? Also, I understand the various conditions where ST elevation loses it's diagnostic value, however without a good history I dont see how can we be sure at all about whether this presentation is old, new, or part of some other pathology. Even if it really is a BBB, we dont know if it is new or not-- so once again, 12 lead?

The crux of the question is whether the 3 lead should suggest that a 12 lead is necessary. Is the 3 lead ST segment truly THAT worthless, as Squad51 said, to the point where it isnt even worth looking at? ...Or does that elevation there raise some suspicion that would suggest further testing is necessary?

Ya got me on the whole ST elevation/ST depression/Q wave thing. I'm still learnin.

I'm not all bent out of shape because my partner didnt run a 12 lead, I'm simply interested in asking WHY he didnt run it. I'm a student and I love learning about this stuff- simple as that.

LOL ... this is like AIM the way these posts are coming!

Basic BBB criteria is QRS greater then .12 (some say .1) in a rhythm that is not ventricular in origin. You can usually discover this on 3-lead. Your strip the QRS is wider then .12. I need a 12-lead to determine LBBB vs RBBB but there are probably people who can do it on 3-lead.

Ok so here is the scoop on the 3-lead vs 12-lead "diagnostic" versus "non-diagnostic" mode:

In patients with BAD infarct, the ST segment will almost always be elevated regardless of whether the monitor is in diagnostic or non-diagnostic mode. Borderline elevation is difficult to assess without a true 12-lead.

I usually have my LP-12 set to do I, II, III so that I can quickly identify IWMI even without doing a 12-lead (lead I depression, lead II, III elevation). Like I said, the obvious ones will be obvious regardless of if you are in diagnostic mode or not.

So, if your patient is having a bad IWMI infarct, you can usually catch it on 3-lead. (Remember, you miss V1->V6 so you can't identify some ant/septal/lateral infarcts but this is because you don't have the precordial leads)

Fiznat check out this one below ... you can see that will be obvious even in only I, II, III.

http://www.med.umich.edu/lrc/baliga/case02/01Q.html

But, because of the filters doing smoothing it may not be perfect, so it doesn't really make sense to say "2mm" of elevation

I will look in my ECGs because I have a great example of a patient with elevation on the 3-lead but with none on the 12 lead. If I can find it I will post it.

Also ... monitor technology marches on ... I don't think this is as much of an issue now as it was with earlier devices.

 

[viostorm]

This isn't the one I was looking for, but shows non-diag vs diag.

Same patient:

Zoll M in non-diagnostic mode:

Diagnostic 12-lead.

These were done within minutes of eachother and no meds/procedures in between.

 

[viostorm]

This is not a great example some AMI are even more obvious then this ... but you should be very suspicious only from the 3-lead the pt was having AMI.

 

[Squad51]

But, because of the filters doing smoothing it may not be perfect, so it doesn't really make sense to say "2mm" of elevation

I will look in my ECGs because I have a great example of a patient with elevation on the 3-lead but with none on the 12 lead. If I can find it I will post it.

Also ... monitor technology marches on ... I don't think this is as much of an issue now as it was with earlier devices.

It is not a "filter" thing. You simply cannot use "monitor" mode to determine ST segment pathology - at all. There are plenty of cases with GROSS (read simply HUGE) ST segment elevation on a transport monitor but nothing on a true twelve lead. The ST segment simply doesn't actually register on the monitor setting. I've got a great .ppt that explains this, but it is too big to post here. Technology will not help. There is simply too much potiential interference at the necessary wavelength.

 

[Squad51]

Same patient:

Zoll M in non-diagnostic mode:

Diagnostic 12-lead.

These were done within minutes of eachother and no meds/procedures in between.

Proving the point...

 

[viostorm]

It is not a "filter" thing. You simply cannot use "monitor" mode to determine ST segment pathology - at all. There are plenty of cases with GROSS (read simply HUGE) ST segment elevation on a transport monitor but nothing on a true twelve lead. The ST segment simply doesn't actually register on the monitor setting. I've got a great .ppt that explains this, but it is too big to post here. Technology will not help. There is simply too much potiential interference at the necessary wavelength.

I think "at all" is a bit strong. Like I suggest and this is only anecdotal, the BAD IWMI STEMI's will be evident regardless of the setting the monitor is in.

Like my post proves, you can be screwed if you trust the monitor in only non-diagnostic mode. But it can be very suggestive. The above ECG is the exception rather then the rule in my experience. Usually the 3 lead is a good representation on the 12-lead. Especially on the LP-12.

 

[12R34Y]

This isn't the one I was looking for, but shows non-diag vs diag.

Same patient:

Zoll M in non-diagnostic mode:

Diagnostic 12-lead.

These were done within minutes of eachother and no meds/procedures in between.

excellent example! Seen a bunch myself.

However, I have to also disagree with the point about depression and ischemia. I have several excellent 12 leads that demonstrate depression only in the inferior leads for example. (no elevation anywhere).

It does occur. althought we all can agree that ST depression can be AMI, as can T wave changes, etc.....EKG is NOT very specific/sensitive tool.

later

 

[viostorm]

excellent example! Seen a bunch myself.

However, I have to also disagree with the point about depression and ischemia. I have several excellent 12 leads that demonstrate depression only in the inferior leads for example. (no elevation anywhere).

It does occur. althought we all can agree that ST depression can be AMI, as can T wave changes, etc.....EKG is NOT very specific/sensitive tool.

later

I've always been confused about ST depression.

How did you end up deciding that the depression was "ischemia"? Did you have enzymes suggestive of myocardial injury? Did you do posterior chest leads? Did they cath the patient and find an occlusion?

Like I said, I'm pretty confused why digoxin causes ST depression pretty much across the board regardless of which lead you are in.

 

[12R34Y]

I've always been confused about ST depression.

How did you end up deciding that the depression was "ischemia"? Did you have enzymes suggestive of myocardial injury? Did you do posterior chest leads? Did they cath the patient and find an occlusion?

Like I said, I'm pretty confused why digoxin causes ST depression pretty much across the board regardless of which lead you are in.

Remember you often won't/shouldn't see an increase in enzymes from ischemia right? remember as soon as they stop the treadmill the depression goes away....... injury/infarct will cause the enzymes to elevate along with a million other things.

So, back to the depression.....It's quite common to see depression (ischemia) in contiguous leads and NO reciprocol ST elevation in the opposite leads (YIKES that would be a STEMI?!!) So you better not see ST elevation or the depression you are seeing are reciprocol changes from the STEMI!

It's complicated, but you can very easily have a local area of the heart be ischemic and NOT infarct. There are just non-specific T wave changes and/or some depression over the leads that look specifically at the area of the heart.

So, your thinking that "If I see ST depression there is ST elevation opposing" says that anytime you have depression you ACTUALLY have a STEMI!.

This is not correct. You can just have depression and have it be just depression and it is TYPICALLY indicative of ischemia.

Get a textbook on 12-leads (Garcia and Holtz) or a cardiologist, they both doa better job at explaining than me.

 

[viostorm]

Get a textbook on 12-leads (Garcia and Holtz) or a cardiologist, they both doa better job at explaining than me.

Thanks 12R34Y!!!

 

[viostorm]

Ok, can anyone explain how you can have ST depression on one side of the heart without elevation when looking at the other side of the heart??????

I went back to my cardiac physiology after this discussion and I still can't explain it.

I thought if you looked directly at the other side of the heart the signal would be reversed and you would have elevation? Like the lead II / avR thingn that look in almost opposite directions.

 

[12R34Y]

Ok, can anyone explain how you can have ST depression on one side of the heart without elevation when looking at the other side of the heart??????

I went back to my cardiac physiology after this discussion and I still can't explain it.

I thought if you looked directly at the other side of the heart the signal would be reversed and you would have elevation? Like the lead II / avR thingn that look in almost opposite directions.

The only advice I can give you is that I think you are kind of "hung up" on the reciprocol changes in the EKG.


If you do a quick google search and type in "ST depression reciprocol change" in the search box you'll find many many many studies that talk about changes in the EKG.

The bottom line is that you can have a huge AMI and NOT have any ST depression anywhere.

You can have ST depression ONLY without STE anywhere else.

One study showed that only 34% of AMI's had any reciprocol changes.

One theory thinks that ST depression is NOT reciprocol to the STE, but ischemia by itself.

So, this is a very complex electrophysiologic phenomenon that even cardiologists can't adequately explain yet.

I also learned this somewhat incorrectly and overly simplified in paramedic school years ago. When talking with the cards guys on my cards rotation I was greatly confused and realized that it wasn't black and white and straightforward in its understanding.

later