EKG question

[themerlin]

To those EKG studs out there, can someone explain to me what reciprocal leads are? I keep hearing the term tossed around, but I haven't been able to find an explanation. From context I figured out that anterior leads are the reciprocal leads in an inferior MI, but I don't get it. How can anterior be reciprocacl to inferior? What would be reciprocal to posterior?

I'm so lost.

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[deleted109597]

Reciprocal leads are leads that are opposite from where the changes are. Thus, if you have a left lateral MI (V5, V6, I, aVL), you would expect changes in aVR, and sometimes V1 and V2 (depending on how lateral, lead placement, etc). A right sided infarct (rV4, aVR) would show reciprocal changes to the left lateral leads. The anterior leads (V1, V2) are not reciprocal to the inferior (II, III, aVF), but they are reciprocal to posterior MI, and that is usually where the word reciprocal is used. Because nobody really uses posterior leads, there is no direct ST elevation on any known lead, but there are reciprocal changes in the anteriors. Inferior MIs can become posterior, depending on blockage.

 

[042686]

Let me start this by saying that I am a paramedic student and ED Tech, so I don't have very distinguished credentials. However, I perform 12 leads EKGs on a daily basis and enjoy learning their interpretation.

Generally, when taking about EKG leads, "reciprocal" can mean "inverse" / "opposite" or more like "complementary". The term "reciprocal" is usually used in the context of EKG interpretation during an acute MI or ischemic event. Reciprocal leads could be considered leads that view an area of the left ventricle that is contiguous with the area of the left ventricle where the acute event is occuring.

You are correct that the anteroseptal leads (v1-v4) can be referred to as showing reciprocal changes to what is seen in the inferior leads (II, III, and aVF) during an acute inferior wall MI. In this case one might see ST segment elevation in inferior leads and ST segment depression in the anteroseptal leads. In this case, the "reciprocal" changes are the ST depressions in the anteroseptal leads. So it happens here that reciprocal changes are those that are occuring in the neighboring area of the left ventricle. The changes in the anteroseptal leads are complementary because they reflect the ischemia surrounding the area of acute injury.

You can see from this that "reciprocal" doesn't really mean a lead opposite to another lead, but rather a change that is opposite to another change (most commonly seen in the leads looking at a neighboring area).

The one instance I can think of when a lead (rather than a ST segment morphology change) is truly "reciprocal" or opposite to another is in the case of acute posterior wall MI. In this case, one might see isolated ST depression in v1 and v2. These are anterior (septal) leads. However, due to their position over the anterior wall of the left ventricle, they will show the opposite of what is occuring in the posterior wall of the left ventricle during acute events (front looks through to back = mirror image effect). So, you can be suspicious of acute posterior wall MI when you see ST depression in v1 and v2.


You can see:

-Reciprocal anteroseptal changes due to acute inferior event (and vice versa)
-Reciprocal lateral changes due to acute anteroseptal event (and vice versa)
-Reciprocal lateral changes due to acute inferior event (and vice versa)
-Reciprocal lateral changes due to acute posterior event (and vice versa)
-Reciprocal anteroseptal changes due to acute lateral event (and vice versa)
etc...

During an acute MI, all you have to do is think about which leads are showing acute changes (ST elevation or ST depression). Then picture which walls of the left ventricle the leads "look at". The leads with ST depression likely "look at" walls of the left ventricle that border the wall of the left ventricle that is having the acute event (seen as ST elevation) The leads that show ST depression are showing "reciprocal changes" to those which show ST elevation. Thats really it.

Hope this helps.

 

[themerlin]

You guys rule. How come this stuff isn't in any of my books? Thank you for the excellent explanation.

 

[ericdamiansean]

You guys rule. How come this stuff isn't in any of my books? Thank you for the excellent explanation.

Cos it's deemed to be additional knowledge..do you know that you can fiddle around with the leads to get different readings as well?

 

[watermen]

Cos it's deemed to be additional knowledge..do you know that you can fiddle around with the leads to get different readings as well?

Are u suppose to fiddle with those things?

 

[ericdamiansean]

Are u suppose to fiddle with those things?

THIS IS MY 1000TH POST!!

You're not supposed to, but sometimes, you've to be innovative.. Imagine if your patient has no legs or arms

I didn't exactly read through this, but it may give you an example.
http://www.mikecowley.co.uk/leads.htm