the EKG axis is still your ally

Sometimes things just aren’t as they appear.  Maybe you thought September would be cool in southwest Michigan.  Perhaps you thought the Super Bowl Champion Patriots would have something other than the worst defense in the league.  Purely hypothetically you’re playing chess with your 10 year-old and think you can cruise to victory … until you don’t notice the bishop waiting to swoop up your queen just when you thought you had her in check.  That’s right ladies and gentlemen, I lost to my 10 year-old in chess this afternoon.

And then there’s this EKG:

~60 y.o. man s/p fall and orthopedic injury, missed evening meds, admitted and awaiting bed. 

So this is a recipe for your shift getting worse.  You received a patient with a hip fracture in sign-out and they plunk down the pre-op EKG which somehow never got done earlier.

As always, start with the rate.  It’s not regular and there’s a couple different things going on, so let’s just count the beats to get a ballpark average.  23 x 6 = 138 so we can certainly say it’s tachycardic.
What’s the rhythm?  That’s a more difficult problem.  Let’s zoom in on a section with narrow complexes first:


I don’t see P waves and it’s irregular; I think we can agree that this section is A fib.  Notice that the rate is a little slower here, averaging about 2.5 big boxes wide so somewhere in the 110-125 range probably.

The EKG then has sections of a somewhat faster, wider complex rhythm, and the natural first inclination is to assume this is V tach.  Let’s zoom in on the faster section:


There’s a couple things that stand out to me in looking at this run.  First of all is that even in the wide complex section, it’s not a regular rhythm.  Sometimes there’s about 8 little boxes between the wide complexes, sometimes it’s more like 10.  It’s still irregular, therefore, which would be odd for monomorphic V tach.  The polarity of the complexes is also the same as the polarity of the narrow complex beats.  We talked last week about how generally in V tach the polarity of the complexes reverses since the electricity is coming from the bottom of the heart rather than the top.

To my mind therefore, the patient has A Fib with RVR with a rate-dependent bundle-branch block.  You see this occasionally, where a patient has LBBB when tachycardic, and more narrow complexes when slower, though not usually all on the same EKG.  I admit I panicked a little when I first saw this EKG; A fib with RVR patients certainly can have short runs of V tach.  After I looked at it more closely I realized I could just give an oral dose of their lopressor and an IV dose of lopressor (I’m a big believer in giving an oral drug along with the IV one so that when the quick acting IV blood pressure medicine wears off you’ve got the longer acting oral one getting up to reasonable levels in the system) which suppressed any further scariness.

Looking at the rest of the EKG, we do see the ST waves elevate and depress in the expected discordant directions of LBBB where the complexes are wide.  These sort of EKG’s where there’s only wide complex beats in sections of the EKG can look a lot like STEMI’s if a person doesn’t notice that an intermittent bundle branch block is present.


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