12 Leads (Axis Deviation and Pericaditis)

[Sublime]

So I am finished with paramedic school and doing my last ride outs but still am unsure about a couple of things that were not taught in class, and do not show up in my book. I want to be able to find things like Left/Right Axis deviation and Pericarditis. Our teacher basically taught us how to find ST elevation and diagnose an MI, but never went over things that could mimic ST elevation like pericarditis.

I know that being able to find Right Axis Deviation can help confirm V-Tach in wide Qrs tachy's, so I would like to be proficient in recognizing that as well. I am having trouble finding places to explain this well, and was wondering if anyone knew a good place on the internet, or even a good book that I could look into.

I thought about buying Bob Page's book (12-Lead EKG for acute and critical care providers), but don't know if it covers those things as well.

Thanks for any info

[Bernhard]

I thought about buying Bob Page's book (12-Lead EKG for acute and critical care providers), but don't know if it covers those things as well.

See his homepage http://www.multileadmedics.com/, in the section "seminar handlouts" you find scripts which may give you some information about your questions and about what's covered in the book.

[systemet]

So I am finished with paramedic school and doing my last ride outs but still am unsure about a couple of things that were not taught in class, and do not show up in my book. I want to be able to find things like Left/Right Axis deviation and Pericarditis. Our teacher basically taught us how to find ST elevation and diagnose an MI, but never went over things that could mimic ST elevation like pericarditis.

Axis deviation is relatively simple.

* Ignore the chest leads (V1... V6, etc.)

* Look at the limb leads, e.g. I, II, III, aVR, aVF, aVL.

(1) Simple method (The "Fonzie sign"). Look at lead I and aVF. If the complexes are mostly positive in both, i.e. "two thumbs up", you have a normal axis, i.e. between 0 and +90.

* negative: this method will lead you to identify some rhythms that are lead aVF negative and lead I positive, that fall in the normal range of 0 to -30 as being left axis deviation.

(2) Most strongly positive limb lead. Find it. Find the next most positive lead. The axis lies somewhere between, e.g. if lead II (+60) is the most positive, and lead aVF (+90) is the next most positive, then the axis is between +60 and +90. Roughly. [Note that to do this, you mentally (or physically turn lead aVR upside down, producing a lead at +30, intermediate to lead I and lead II, this is called the "Carbrea rearrangement". A variation on the same theme, is to find the most isoelectric lead (i.e. the lead with the smallest QRS), and understand that the axis is perpendicular to this. So if lead I (0 degrees) is roughly isoelectric, we know the axis is either roughly +90 degrees (normal), or - 90 degrees (left axis deviation). If we see leads in the direction of 90 degrees, e.g. aVF (+90) III (+120), lead II (+60) showing mostly positive QRS complexes, then we can guess the axis at about + 90 degrees.

* This method is quite quick, but gives a rough answer, and requires that you know how the leads are oriented, i.e. Einthoven's triangle. Look here: http://t1.gstatic.com/images?q=tbn:ANd9GcRjhqeBYB4xNkxmFUv6OTpDk8RoGkFcwGikxNRiiWOkqMjU1pjI

(3) Geometric (pain in the ass) method: Take any two leads. Measure the height of the Q, R and S waves in the respective QRS complexes relative to the baseline. Find the net deflection, i.e. height (R wave) - height (Q) wave and height (S) wave. Draw a pair of axes corresponding to the leads in question, e.g. a line a 0 for lead I or a line at +60 for lead II. Mark the relative net deflections of the QRS complexes in arbitrary units across each axis. Draw lines perpendicular to this point. Where they intersect draw another line through the center of the graph, and the angle of this line is your axis. This can also be solved for with trignometry. This is sort of explained here: http://www.madsci.com/manu/ekg_axis.htm

(4) Just use the reading on the LP12, but confirm that it's somewhere in the realms of reality using (1) and (2).

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Pericarditis is hard to diagnose via ECG. Classic findings are diffuse ST changes, PR depression, concave upwards sloped ST elevation, and an ST/T ratio of > 0.25. Sometimes QRS alternans is present. But these are very insensitive for pericarditis. Physical exam can give you the triad of hypotension, JVD and muffled heart sounds (i.e. Beck's triad) +/- pericardial friction rub in acute cases with tamponade. But this is also quite insensitive, and depends on how familiar you are with cardiac auscultation. Typically the pain associated with pericarditis is pleuritic and relieved by leaning forwards.

However, it's a really hard dx to make prehospitally, and the ECG is only helpful in a very small fraction of cases.

I know that being able to find Right Axis Deviation can help confirm V-Tach in wide Qrs tachy's, so I would like to be proficient in recognizing that as well. I am having trouble finding places to explain this well, and was wondering if anyone knew a good place on the internet, or even a good book that I could look into.

I'm in the middle of a thread on another site debating this issue. I really believe that we should default all interpretation of WCT in the field as VT, outside of maybe a few situations where you're doing long distance interfacility transports. There's just too much risk in giving beta-blockers or CCBs to patients with possible preexcitation or VT.

That being said, extreme axis deviation (also called "intermediate axis" or "northwest axis" i.e. between +180 to -90 degrees) is fairly specific for VT. That being said, VT can present with any axis. A right axis points toward VT when a LBBB-like pattern is present, as we would expect LAD with LBBB w/ aberrancy.

This page descibes this particular situation well:

https://www.ebmedicine.net/topics.php?paction=showTopicSeg&topic_id=57&seg_id=1074

I thought about buying Bob Page's book (12-Lead EKG for acute and critical care providers), but don't know if it covers those things as well.

Thanks for any info

This sounds like a good book. I don't have it, but would love to pick up a copy. This one looks pretty decent too: http://www.12leadecg.com/full/

I do have a copy of Ken Grauer's ECG Pocket Brain. I like it a lot.

http://www.amazon.com/ECG-Pocket-Brain-Guide-Interpretation/dp/1930553145/ref=sr_1_1?ie=UTF8&qid=1323612648&sr=8-1

[Sublime]

Thanks systemet, although your explanation was very good, as I am a more visual learner so I still don't have a grasp on it. But with the resources in the links you provided, I think I can figure it out eventually. A lot of information on that EB Medicine site, unfortunately I don't have the time to read it all right now. I found some more resources after reading your reply, and I figured i'd post them in case anyone else was curious about axis deviation.

Video explanation by a DR on axis deviation

This sight has a frontal axis tutorial as well. http://www.blaufuss.org/

Thanks again for your help.

[mobey]

So I am finished with paramedic school and doing my last ride outs but still am unsure about a couple of things that were not taught in class, and do not show up in my book. I want to be able to find things like Left/Right Axis deviation and Pericarditis. Our teacher basically taught us how to find ST elevation and diagnose an MI, but never went over things that could mimic ST elevation like pericarditis.

Wow,...... Dude that is a piss poor school!

Forget Axis deviation for now and concentrate on ST mimic's, and DD of widened QRS.

My suggestion is to find a 12 lead course and attend it! You can dredge through all the websites and self-learn if you like......

Of course that means you will be a "self-taught" Paramedic

If I were you I would attend a class and attempt to send the bill to the school as they have not prepared you to work as an ALS provider...... That is what you payed them to do right?