ALS 12 lead assessment

Benjamin Henry

Forum Ride Along
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Hey there guys,

I am a soon to be medic student and I was curious as to what medics are looking for when they look at a 12 lead of a chest pain patient? And if it’s just for STEMI rule in/out, is there a systematic way to do it?

Thanks
 

justin1232

Forum Lieutenant
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Anything abnormal. From STEMI to NSTEMi, to bundle branch blocks, ectopi, AV blocks, Accessory bypass tracks and so on. You will learn it all in school. I work my way around so I look at 1 and AVL , 2/3/avf. Then V1-v6
 

NPO

Forum Deputy Chief
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Hey there guys,

I am a soon to be medic student and I was curious as to what medics are looking for when they look at a 12 lead of a chest pain patient? And if it’s just for STEMI rule in/out, is there a systematic way to do it?

Thanks
There is much more than just rule in/out.

But yes, there is a systemic method to it. The EKG is laid in anatomic regions. (I've attached a picture of it to show you.) Most people suggest going by region; note, this does not mean going from I to II, to III, and so on since it's broken up

There are many reasons we take an EKG. We can obviously look for a STEMI, but we can also look for other signs of ischemia such as T wave inversions or ST depression, electrolyte changes like hyper- and hypo-kalemia cause T wave changes, we may be looking for electrical blocks like a 2nd or 3rd degree (as oppose to a blockage of an artery). Then there are things like Brugada, de Winters, Wellens, etc all signs of more complicated or impending cardiac problems.

When you first look at an EKG, it's easy to skim over it or jump right to the interpretation. Here is what I recommend:

Start with Lead II. This is the most common lead used for rhythm analysis. Go one wave and segment at a time. Look at the P wave. Is it there? Is it upright? Is it shaped normally? How close or far is it to the QRS? Then look at the QRS. Is it wide or narrow? Is the axis normal or appropriate? Does it's morphology look normal? Then look at the T wave. Is the ST segment depressed or elevated? Is there an ST segment? Is the T wave upright, inverted, flattened, peaked or elongated?

Now compare several QRS's, from any leads. Does the rhythm look regular? The QRSs will be different shapes in different leads, but are they regular, meaning so they occur at regular, consistent, predictable intervals.

Now you can move on to looking at all of the leads. You already looked at Lead II, so I start there. II, III, and aVF Are all anatomically related and all look at the inferior areas. Evaluate the inferior leads for ischemia. Then I'll move to Septal, Anterior, Lateral and High Lateral.

Lastly I'll look at aVR. In school I was (jokingly) taught the R in aVR stood for retarded because that lead was useless. In time I've learned that to be quite false. There are some very important things you can find here like triple vessel disease or a significant LMCA blockage. So don't leave it out!
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