EKG of the Week
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+ EKG Interpretation
Dr. Ohlbaum's Explanation
This is a fun EKG.
We usually start looking at rhythm in terms of fast or slow, regular or irregular, wide or narrow, and then look for P waves. But in this case, we are going to need to turn that around a little. The QRS's are irregular and a bit wide, but, there are P waves. In fact, there are quite a few P waves and not quite as many QRS complexes.
So, I want to look first at the P waves. Where are the P waves? Well if you look carefully there are P waves at a rate of 110 that march thru regularly though many of them are hiding in the T waves. (You can see them easily in the longer interval between 3rd and 4th QRS that we will come back to). For most of the EKG every other one of those P waves is conducted. That means that most of this EKG is sinus rhythm (actually, not slow so not sinus brady) with some of the Ps conducted (the ones right before the QRS's) and some not conducted (the ones on the Ts) so a 2nd degree AV block . If the whole thing is 2:1 (ie every other P wave conducted) you cannot say if it is Mobitz 1 or 2 so you can just say it is a 2:1 pattern.
But here there is something worse, you see a gap between the 3rd and 4th QRS. There is an area where there are 2 nonconducted P waves- one in the T and then one extra. That makes this a HIGH GRADE 2nd degree AV block. It is not a 3rd degree because that would have no relationship between the P and the QRS and the QRS's would be perfectly regular at the rate of the escape mechanism. The QRS is wide because there is a LBBB. I think the ST and Ts are consistent with his LBBB and a P sitting on all the Ts.
So, sinus rhythm with 2nd degree AV block with periods of 2:1 conduction and areas of high grade AV block, and a LBBB.
