Unrecognized Limb Lead Misplacement?

Dr. Smith's ECG Blog has a new case up, "Reperfusion through collaterals associated with nitroglycerin, lateral MI with reciprocal T-wave inversion in lead III," with a pretty stark change in the initial 12-Leads. However, I have a hunch the stark change was really a change in the limb lead positions!

ECG 1 and ECG 2: Limb Leads Only

Look at leads I and II, notice how they "swap" positions between the two 12-Leads. Now look at aVL and aVF, notice how the "swap" positions too. Now take a look at lead III. It goes from inverted P's and T's with a Qr complex, to upright P's and T's with a Rs complex.

I propose that this change is due to a simple reversal of two leads. If we take a look at our friend Einthoven's Triangle (we covered this in a previous post on the S5 Lead) we can see that this makes sense!

LA/LL Swap: Einthoven's Triangle is "Flipped"

We can see that Lead I is actually looking at Lead II and Lead II is actually looking at Lead I; confirmed with ECG's 1 and 2. Lead III becomes an inverted Lead III; confirmed again in the original ECG's. This looks like a case of an unrecognized left arm and left leg lead reversal.

What I find most interesting is if you compare every ECG except the first, it appears to be a case with subtle posteriolateral changes that may have been missed had there not been the lead reversal!