Definition of Anatomically Contiguous Leads, a Problem

[OVeractiveBrain]

In a recent debate over whether an ST elevation was considered significant or not a nit-picky argument over the definitions of some words came out.

The scenario:

There is marked ST elevation in the precordial leads V1-V3. In a lecture and in most course manuals, v1 and v2 are rigidly defined as "SEPTAL" while V3 and V4 are defined as "ANTERIOR." In order to be a significant finding and suspect of Myocardial Infarction, there must be "st elevation in two or more anatomically contiguous leads."

The argument:

My argument is that despite the convenient summary chart in ACLS which defines V1/V2 as septal and V3/V4 as anterior, the electrode placement is such that there is a continuous picture of the heart, beginning from the right side of the septal wall in V1 down to a lateral/inferior view of the left ventricle in V6. That being said, V2 and V3 should be considered anatomically contiguous. In fact, the muscles of the heart have no true boundaries "Septal" "Anterior" or "Inferior", those are arbitrary definitions of general space used by clinicians to describe and anticipate the location of arterial blockage. IN this particular scenario, I suggested that an occlusion of the diagonal branch of the Left Anterior Descending coronary artery could lead to an infarction of mainly the septal wall but also part of the anterior wall. Thusly, from a technical standpoint, v1-v3 are anatomically contiguous and are all technically significant, and would lead a clinician to suspect a blockage more proximal to the aorta given the expanse of the area infarcted.

The counter argument, which the instructor reinforced (and I believe incorrectly) was that since the chart defines V1/V2 as contiguous, V3/V4 as contiguous but NOT V2/V3, and therefore there is some aberrant recording in lead V3 and only a septal infarction is suspected.

While this argument would not change prehospital care, it might lead to a misdiagnosing of the anatomy, and why I have taken such pains to determine a true answer. It is possible that the septal wall be fed by the right coronary artery. If we assume that the ST elevation is insignificant, and that it is only a septal wall MI, it is possible to incorrectly assume a right coronary artery occlusion, whereas we would be more likely to be correct assuming a left coronary artery blockage from V1-V3 significance.

The question I pose is, and from strictly a technical definition standpoint: are precordial leads contiguous with one another, V1 --> V6 as we go across the chest.

Thanks to all those who reply.

-Overactive

[AZCEP]

Without laying the heart out on a table and cutting it into easy to define sections, you can't really hold such tight definitions to it.

V1-->V2-->V3-->V4-->V5-->V6 are all contiguous, but some will argue that if V3 and V4 are contiguous then V1 and V6 could be as well. :roll:

The kicker is when you explain that V6 does in fact show septal activity, only reverse of V1.

[fiznat]

Wrong forum, momo!

If you had looked in the correct forum for this (ALS), you would have seen that I already asked this question! You'd think someone with an "overactive brain" might have realized this on his own.

I was way less verbose, also. :wink:

haha.. Anyways, we were right bro. Dream Team: 1 DT: 0

http://www.emtcity.com/phpBB2/viewtopic.php?p=87425

[OVeractiveBrain]

Ill wrong forum you Fizzy.

Baaaaaaaaah!

Didnt realize there was an ALS forum (thus the ranking Newbie).

Good to hear that were right and that THE INSTRUCTOR, who is supposedly imparting his vast wisdom upon us is wrong. Hope he doesnt read these forums.