12 lead EKG interpretation algorhithm

[medicaltransient]

Here I am at the vacation station for 5 shifts in a row. I would like to configure an algorithm for 12 lead EKG interpretation I am most of the way done with it but I am taking some time to research and seek the input of you guys and girls. The areas of the algorithm that are incomplete right now are RBBB with ST segment elevation and LVH with ST segment elevation.

Do y'all transmit the EKG when you know you have a mimicker?
Do you activate the cath lab when your tracing meets Sgarbossas criteria?
Are there and combinations of axis deviation and BBB that warrant an activation of the cath lab?
Do you activate the cath lab for RBBB with ST segment elevation?

Thanks for your help, I just opened a red bull and I have opened prehospital 12-lead ECG blog. I'm ready for 12 lead beast mode!

 

[Aprz]

The link below is the suspected carciac ischemia protocol in Santa Clara County, CA.

https://www.sccgov.org/sites/ems/Documents/pcm700/700-A/Policy 700-A08 effectiveFebruary2015.pdf

They can transmit the 12-lead whenever they want, but they must transmit and activate the cath lab if the monitor says *** ACUTE MI *** or some variation of that.

For bundle branch blocks, I would look at lead V1 to see if it is mostly positive (R/S > 1) or negative (R/S < 1).

A right bundle branch block (RBBB) will have a mostly positive complex. It will typically have a bunny ear morphology with second R wave being taller ie rsR'. It can have a qR morphology. I will then look at lead I and V6 to see if it has a Rs morphology. I've noticed that V6 can be more equiphasic or even have an rS morphology if the patient has pathological left axis deviation or a left anterior fascicular block (*LAFB), but lead I will still have the Rs wave. RBBB can have mild ST depression in lead V1-3. I consided normal axis and right axis deviation to be normal for RBBB.

If the patient has a mostly negative complex, I will consider it to be left bundle branch block (LBBB) morphology. Most leads should be monophasic or mostly one way. Lead I and V6 will be almost or completely positive. V1-3 will typically have ST elevation. I consider normal and left axis deviation to be normal for LBBB.

If it doesn't meet the morphology criteria, I'll call it am intraventricular conduction delay (IVCD) and consider the possibility of hyperkalemia. If it is a tachycardia a rate of 115, I'll comsider it ventricular etiology; not a SVT with aberrancy. I don't usually consider axis deviation in BBB to be a sign of MI, but I suppose thaf would make sense. I stick with smith-sgarbossa criteria for determining MI in BBB.

I use the smith-sgarbossa modified critetia instead of sgarbossa criteria. Instead of ST elevation >5 mm being the criteria, I look at how deep the S wave is compared to the amount of ST elevation. I personally use the magic number 0.2. If ST elevation divided by the R wave in mm is 0.2 or less then I will consider the ST elevation within normal limits. This is easier to apply without doing the math. For every 5 small boxes for the R wave, 1 small box of ST elevation is acceptable. This can be applied to other conditions like ventricular aneursym (Dr. Smith uses 0.36 as the magic number) or left ventricular hypertrophy (LVH).

I do look for concordance of T waves and ST elevation/depression. Concordance or excessive ST elevation can meen the patient is having an MI.

V5-6 can be weird in LBBB. T wave concordance can be normal in those leads with LBBB.

A lot of people will apply the smith-sgarbossa criteria to ventricular paced rhythms too.

*LAFB = pathological left axis deviation (excluding other causes). Lead I will be mostly positive. II, III, and aVF will be mostly negative. This means the meam QRS vector will be between -45 and -90 degrees. People sometime will make it more complex considering qR in the lateral leads (particularly I) and rS in the inferior leads (II, III, and aVF).

I would still transmit the 12 lead even if it doesn't say any variation of *** ACUTE MI *** and I would call medical direction or the hospital telling them what I see and think.

 

[medicaltransient]

Yes but does RBBB with Left axis deviation mean anything and should under any circumstance you activate the cath lab?

 

[SeeNoMore]

Here I am at the vacation station for 5 shifts in a row. I would like to configure an algorithm for 12 lead EKG interpretation I am most of the way done with it but I am taking some time to research and seek the input of you guys and girls. The areas of the algorithm that are incomplete right now are RBBB with ST segment elevation and LVH with ST segment elevation.

Do y'all transmit the EKG when you know you have a mimicker?
Do you activate the cath lab when your tracing meets Sgarbossas criteria?
Are there and combinations of axis deviation and BBB that warrant an activation of the cath lab?
Do you activate the cath lab for RBBB with ST segment elevation?

Thanks for your help, I just opened a red bull and I have opened prehospital 12-lead ECG blog. I'm ready for 12 lead beast mode!

I'm having some trouble understanding what you are asking. What is a mimicker? Do you mean any EKG with a recognized STEMI mimic regardless of other factrors? If so, then no.

If I have a 12 lead that meets Sgarbossa criteria for a STEMI then yes, I activate the cath lab. The same goes for ST elevation with a RBBB , which I belive is consistent with the most recent AHA guidelines.

 

[Aprz]

Yes but does RBBB with Left axis deviation mean anything and should under any circumstance you activate the cath lab?

Follow your protocols. If you protocols completely leaves it up to you, I would only activate the cath lab if it is a clear cut STEMI no questions asked. If it is not an obvious STEMI, do not activate the cath lab.

I feel like you are over thinking this. A STEMI can cause axis deviation, but axis deviation doesn't mean it is a STEMI. Normal axis doesn't rule out STEMI either. I do not use the axis to determine if it is a STEMI or not. I primarily look at ST and T wave changes in regard to STEMI. Is it elevated or depressed? What kind of morphology does it have? Are there reciprocal changes? I will consider the axis too, especially for anterior and posterior wall MIs. When I see late R-wave progression and subtle ST elevation in the anterior leads, red alarms will be going off for anterior wall MI. When I see early R-wave progression eg V1-2 already have decent size R-waves with ST depression in the anterior leads, I will seriously consider the possibility of a posterior wall MI. Look at the whole ECG and the patient.

Give away with STEMI mimics are the T-waves/ST changes are discordant with the terminal or mean of the QRS wave. I also apply the 0.2 rule I mentioned earlier. I know what STEMI-mimics look like too.

Left ventricular hypertrophy is the #1 mimic. Use sokolow voltage criteria or cornell's critieria. May have ST elevation without ST depression and T-wave changes. May have ST elevation and depression "strain patterns" throughout the ECG.

Left Bundle Branch Block. Look at I, V1, and V6 like I said. The ST changes and T-waves should be mostly discordant (exception of V5-6 like I said, which has caused confusion for me in the past).

Ventricular paced rhythm. Smith-sgarbossa criteria I think haven't been studied on this or something like that, but people apply it anyway. Pacer spikes may not be easily visible.

Pericarditis, although I think people over diagnosis this. ST elevation with no ST depression throughout the ST elevation. Pericarditis and wrap around type III LAD occlusion may look similar. Be careful!

I don't consider RBBB to be a STEMI-mimic even though Brandon's website listed it as one.

Ventricular aneurysm will get me sometimes... Apply the 0.2 rule. 0.36 may be better if you are willing to do the math. Morphology may look like a STEMI. I think this one can be hard to tell sometimes and easily look like a STEMI. In the heat the moment, I would probably activate these patients because at a glance they aren't that easy to tell in my opinion.

Benign Early Repolarization (BER) is another common STEMI-mimic. There should not be any reciprocal changes and consider the excessiveness of the ST elevation. The ST elevation is usually very very very little. I find this more common in young patients.

Anyhow... know what the STEMI mimics look like. Know what to look for. Axis isn't one of them. Axis can help support finding a STEMI (I find it most useful for anterior and posterior wall MI rather than the MIs you seen in the frontal axis), but does not rule in or out a STEMI. Look at the ST elevation/depression compared to the R and S wave of the QRS complex, morphology, concordance/discordance of ST/T changes, and look at the patient too when you get a chance.

Like I said, RBBB + LAD could be a bifascicular block. LAFB = pathological LAD. I would not worry about it unless the patient was symptomatic and as a paramedic there isn't anything you can really do for this patient other than treat the symptoms and transport. I would not activate that cath lab for a bifascicular or trifascicular block because those aren't STEMIs.

 

[TomB]

Do y'all transmit the EKG when you know you have a mimicker?

* I don't transmit if I know I have a mimic (why would you?) but I tell my paramedics they are welcome to transmit for a consult if they have a concern.

Do you activate the cath lab when your tracing meets Sgarbossas criteria?

* Our STEMI protocol does not allow automatic prehospital activation for LBBB but occasionally we ignore the rules. The issue with things like de Winter ST/T-waves, excessive discordance, and ST-elevation in lead aVR is that the ED docs have to be on the same page. If they're not it's just going to cause problems calling these from the field.

Are there and combinations of axis deviation and BBB that warrant an activation of the cath lab?

* Not unless STEMI is present. Bifascicular block (by itself) is not an indication for an emergent cath.

Do you activate the cath lab for RBBB with ST segment elevation?

* If we suspect STEMI? Yes.

 

[medicaltransient]

Do y'all transmit the EKG when you know you have a mimicker?

* I don't transmit if I know I have a mimic (why would you?) but I tell my paramedics they are welcome to transmit for a consult if they have a concern.

Do you activate the cath lab when your tracing meets Sgarbossas criteria?

* Our STEMI protocol does not allow automatic prehospital activation for LBBB but occasionally we ignore the rules. The issue with things like de Winter ST/T-waves, excessive discordance, and ST-elevation in lead aVR is that the ED docs have to be on the same page. If they're not it's just going to cause problems calling these from the field.

Are there and combinations of axis deviation and BBB that warrant an activation of the cath lab?

* Not unless STEMI is present. Bifascicular block (by itself) is not an indication for an emergent cath.

Do you activate the cath lab for RBBB with ST segment elevation?

* If we suspect STEMI? Yes.

Thanks

 

[NPO]

We have quite a bit left up to the paramedic and clinical judgement in Kern County CA.

We generally transmission every 12-lead that's obtained but that's not a rule. The ACS protocol dies say to transmit if the monitor reads ACUTE MI, however prior to that in the algorithm is "If acute MI is suspected immediate notification of receiving facility should be attempted."

There is no definition on what to activate, for example if you disagree with the exclusion or inclusion of ACUTE MI on the monitor's interpretation, it is left to paramedic discretion. Also, we frequently consult the receiving facility MD for their interpretation on the EKG if the suspected MI is not obvious.

We do not activate cath lab for LBBB as of this year.