What rhythm is this?

[bayleaf36ff]

I consider myself to be rather decent at reading rhythms, but this one has me stumped. Notice someone wrote "7 sec pause on the top"... That's how much time passed between 2 of these QRS complexes. There's a QRS just off the picture to the left... It's followed by 28 P waves, then you get the first QRS that you can see.



At first I immediately thought Mobitz II or 3rd degree. But here's the problem: All AVBs produce regular rhythms, and type 2 and 3rd degree are consistent in how often they drop a complex (2:1, 3:1, etc). This rhythm goes from 8:1 to 28:1 to 8:1 to 6:1... Completely irregular.

This is obviously not 1st degree.

The PR is consistent, so it's not 2nd degree type I.

2nd degree type II conducts a consistent number of QRSs (every 3rd, every 4th, etc.), and is therefore regular, so it's not that one.

It's definitely not 3rd degree, because you have a consistent PR interval, and the QRSs definitely follow a specific P wave, meaning there's no AV disassociation.

The P waves have a rate of about 250, and the P aves are upright, so it's definitely atrial in origin. If you measure the R-R, you get a rate of about 25-30.

The only other thing I can think of that looks anything like this is A flutter... 250 is fast enough to be a flutter. The only problem is that A flutter is also a regular rhythm, and is also consistent in how often it misses a complex (2:1, 3:1, etc), or will occassionally have a slight variation... definitely not this much. We can rule out A flutter.

So it's atrial in origin, but there's generally obviously no conduction to the ventricles. The problem is therefore junctional, correct? But we've already ruled out every AVB.

What else could this be?
Jeremy

[AmandaWIRN]

Hmmmmm, my first thought was third degree block with a ventricular pause, but you say there is correlation between the p's & qrs complexes (where there ARE qrs), so maybe not... it's hard to see details in the picture, so it's hard to say...

[bayleaf36ff]

Here it is a bit larger...
Jeremy

[MICU-RN]

I am interested in knowing this one. I thought Complete heart block. I looked at the last PR interval and its less that the prior two.

[bayleaf36ff]

http://www.fammed.wisc.edu/pcc/ecg/images/fig22.jpg

That's a good 3rd degree... That's how much the PR interval changes in a true 3rd degree. The PR interval on my strip stays between .19 and .20, which is an acceptable variation. 3rd degree is also a regular rhythm. This is way too irregular.

I gave this to 3 of our cardiologists, and none of them could figure it out either. We unfortunately don't have EPs at our hospital... I'm sure they would know what it is.

Jeremy

[maxiner]

I'm no expert here but it looks like a period of ventricular standstill. None of the atrial contractions were able to conduct an impulse to generate a QRS complex.

[NEHuskerRN]

I agree with maxiner...course dead looks like dead to me before those QRSs come back in!!