EKG of the Week

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+ EKG Interpretation

Dr. Ohlbaum's Explanation

There is a lot going on on this EKG but I really want to focus on the RHYTHM.

The computer read it as atrial fib, but is it? You need to realize that the computer calls everything irregular as atrial fib, without even looking for P waves. It will often call even sinus with PACs afib so we need to look beyond what the computer says (we do not want to anticoagulated PACs!)

Are there P waves? Yes clearly, if you look at the inferior leads or Vl there are clear P waves. You can take calipers and march those P waves thru the whole EKG (I think the easiest is to look at the negative part of the Pin Vl). So, the mechanism for the atrial contractions is sinus rhythm, and it is actually fast tho calling it sinus tach is going to be misleading so just "sinus rhythm".

Now, is there a QRS for every P? Now is where it gets tricky. You can see that some Ps are conducted and some are not. That makes it a 2nd degree AV block. Is it Mobitz I or II? Well if you look at the beats after the missed QRS's the PR is short, next one long and then one dropped, that pattern is thru the whole tracing, so Mobitz I.

So ... rhythm is sinus with 2nd degree AV block, Mobitz I.

He has a funny QRS, not really wide enough to call a bundle branch block and does not fit morphology for either but he does have an extreme left axis so you could call a left anterior fascicular block (synonym for left anterior hemiblock). He also has ST depression and T inversion anterior and laterally suggesting anterolateral ischemia.

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