# How important is axis deviation in EMS?



## VirginiaEMT (Jul 11, 2012)

How important is it to be able to determine left or right axis deviation in EMS? Why?


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## usalsfyre (Jul 11, 2012)

Important if your using a 12 less for more than STEMI determination. Useful for things like determining VT vs abarent conduction, heart strain patterns, LVH and so much more.


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## TomB (Jul 11, 2012)

I wrote a blog post to help answer this question.

http://ems12lead.com/2010/12/why-learn-axis/


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## 46Young (Jul 11, 2012)

TomB probably covered this already within his blog, but Axis is useful for determining a ventricular focus (extreme RAD, for example) versus a supraventricular focus with aberrancy, or the presence of hemiblocks, which could possibly contraindicate antiarrhtymics if two or more blocks are currently present, be it supraventricular, junctional, or intra-ventricular.

Bob Page shows a video of his daughter, five at the time, determining axis deviation using "up, up, down," "down, down, down," etc. It's that easy.


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## Christopher (Jul 11, 2012)

usalsfyre said:


> Useful for things like determining VT vs abarent conduction





46Young said:


> ...but Axis is useful for determining a ventricular focus (extreme RAD, for example) versus a supraventricular focus with aberrancy...



Axis is useful for *ruling in VT* but not ruling out VT. It should not be used to support treating SVT w/ aberrancy. I need to finish my VT Myths series.

Here's another approach for determining axis using I and aVF.


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## DrankTheKoolaid (Jul 11, 2012)

Thanks for posting that link Chris.  Somehow all this time I have not been aware of you blog.  I Love It!   Thanks for sharing your excellent knowledge base with us all


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## Melclin (Jul 11, 2012)

TomB said:


> I wrote a blog post to help answer this question.
> 
> http://ems12lead.com/2010/12/why-learn-axis/



Highly recommend these. 

The only resource on axis that really helped me _understand_ axis.


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## the_negro_puppy (Jul 11, 2012)

We are not taught about L/R axis in our 12 lead training. A few people teach themselves. Ill probably have a look over in the future.

the lifepak 12 will tell me anyway right? ^_^<_<:wub:


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## NYMedic828 (Jul 11, 2012)

the_negro_puppy said:


> We are not taught about L/R axis in our 12 lead training. A few people teach themselves. Ill probably have a look over in the future.
> 
> the lifepak 12 will tell me anyway right? ^_^<_<:wub:


Same


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## Jambi (Jul 11, 2012)

We were taught Axis Deviation in my paramedic program but the focus was using as a tool to confirm suspicion of a cardiac event when the 12-lead wasn't spitting out information.  We were taught nothing about using it to identify LVH,VT, or anything else.


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## ZootownMedic (Jul 11, 2012)

VT will have an extreme right axis which is useful in ruling it in. I have never heard of it being useful in determining LVH though or any other types of enlargement or hypertrophy.....I didn't think an axis was a diagnostic tool for this, just examining specfic V-leads.


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## Christopher (Jul 11, 2012)

SmokeMedic said:


> VT will have an extreme right axis which is useful in ruling it in...



VT can have any axis, even a normal axis (albeit rare)!


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## ZootownMedic (Jul 11, 2012)

Christopher said:


> VT can have any axis, even a normal axis (albeit rare)!



Interesting....that is the first I have ever heard of it. I was taught that a wide-complex V-tach is going to always have a extreme right axis. This and being able to measure the nader point assist in differentiating it from say SVT with abberancy. 

Please....explain?


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## Christopher (Jul 11, 2012)

SmokeMedic said:


> Interesting....that is the first I have ever heard of it. I was taught that a wide-complex V-tach is going to always have a extreme right axis. This and being able to measure the nader point assist in differentiating it from say SVT with abberancy.
> 
> Please....explain?



It all depends on where the VT starts and how it goes out through the ventricles.

An origin in the apex is going to have a different axis than an origin in the right ventricular outflow tract. An origin in the right ventricle will have an LBBB-morphology and could have right axis deviation. An origin in the left ventricle will have an RBBB-morphology and could have a superior axis. Lots of options.

A picture is worth 1000 words, so while this paper gets pretty deep, the illustrations of the ventricles with accompanying ECG's is great and helped me a lot.


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## TomB (Jul 12, 2012)

This is one of the most dangerous EMS myths ever created (that VT will have a right superior axis). As Christopher said, a right superior axis can help rule in VT but VT can have an axis in any quadrant. The most important criterion for VT is "wide and fast". This is one area where 12-lead ECG education has done some harm, IMHO.


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## NYMedic828 (Jul 12, 2012)

So, I just read Tom's 6 parts to axis deviation.

Absolutely phenomenal read, so glad I read it. I was clueless before. 


Now my question is, what happens when you can't find a lead that is relatively equiphasic, or can't decide which is the most relatively equiphasic?


Like this for example








How does one decide where to start on choosing a vector?


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## Christopher (Jul 12, 2012)

NYMedic828 said:


> Like this for example
> How does one decide where to start on choosing a vector?



Leads I and aVF are both positive, so you can localize it to between 0 and 90 degrees at least (i.e. Normal). Furthermore, looking at aVL you can see it points away. The perpendicular lead to aVL is Lead II, so it should be to the "left" of Lead II but to the "right" of aVF because Lead I is positive.

Somewhere between 60 and 90, probably closer to 90 since aVL is more negative than positive.

I've done up a drawing to help, where I fill in the halves associated with each lead's polarity on the axis wheel. Where they all intersect is where your axis lies.


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## Christopher (Jul 12, 2012)

Much cleaner picture. Lead labels are on their positive pole, dashed lines are the leads negative pole. Please excuse my inability to draw 30 degree increments.


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## Christopher (Jul 12, 2012)

Corky said:


> Thanks for posting that link Chris.  Somehow all this time I have not been aware of you blog.  I Love It!   Thanks for sharing your excellent knowledge base with us all



I've added another EKG Myth: "VT can't have that axis"!


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## Sublime (Jul 23, 2012)

There is some great resources here for learning how to determine Axis in this thread, but no where that explains how axis can help in clinical findings.

It is mentioned that identification of Axis can help you rule in VT, find blocks, find LVH.... but I can't find anything that really explains how to use axis to find these things.


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## Christopher (Jul 23, 2012)

Sublime said:


> There is some great resources here for learning how to determine Axis in this thread, but no where that explains how axis can help in clinical findings.
> 
> It is mentioned that identification of Axis can help you rule in VT, find blocks, find LVH.... but I can't find anything that really explains how to use axis to find these things.



Clinical uses of axis deviation...hmm.

Dr. Tomas Garcia would say, "consider the company it keeps."

Right superior axis? Ventricular rhythms or lead misplacement
Pathological left axis deviation? Left Anterior Fasicular Block from a new or old MI/ischemia
Right axis deviation? Acute/chronic pulmonary diseases
LBBB and RAD? Very rare and always abnormal, consider a technical failure as the cause.

If you factor in the Z-axis as well as the frontal axis you can glean a lot more information:

I and V6 opposite? Consider lead misplacement
Left axis deviation and poor R-wave progression? Consider MI (old or new).
Right axis deviation and tall R-waves in right precordials? Consider Right-heart strain (acute or chronic)

The honest answer is you probably don't need it. A proficient paramedic can treat all manners of patients effectively without ever knowing the mean axis of the heart. However, as with anything, the greater your understanding of how the body functions, the better clinical care you will provide your patient.


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## MSDeltaFlt (Jul 23, 2012)

Now learning all of the what's and the why's of axis deviation doesn't hold a lot of water unless you know how to apply the knowledge in the real world.

Now what is one good example of a real world application of axis deviation?  I mean besides ventricular based rhythms.  I'm talking about some of the stuff we see on a regular basis.


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