EKG

Re-charging the batteries

Where was I 1 year ago today?  Working hard attending a conference so that I could gain additional pearls and insight to teach all of you.

AM9A1516

It may have been in Costa Rica.  And even if I didn’t learn a ton (though feel free to check out the podcast Jesse and I did when I got back) I at least had a chance to re-charge the batteries and come back fresh.  What does that have to do with today’s case?  Read on.

I put this one in more as a board review point than necessarily an EKG quiz.  Honestly I was worried this one was too easy, and I think it would have been had I used a multiple choice format.  But, fortunately for me, it was open-ended leaving more room for discussion.

20171106_Li
~70 y.o. woman with h/o manic depression presents with tremor, dizziness, weakness.

Note that usually the vignette has a bunch of vague cardiac related complaints.  Today we see tremor and a history of manic depression.   I think some people interpreted that to imply a thyroid issue, but remember, tremor is going to occur much more with hyperthyroid which will more likely give a tachy rather than brady EKG.  A bunch of people did say “look at the med list;” they weren’t wrong.

So.  As always, rate.  It’s markedly slow, averaging in the 40’s (even counting the premature beat early in the rhythm strip).

Let’s look at the rhythm.  There do look to be some P waves late in the rhythm strip that are absent early in the EKG (though a P wave ironically appears to be present before the apparent premature beat).  For the most part however I really don’t appreciate P waves.  The QRS maintains narrow complex however so the patient appears to be varying between a sinus brady and a junctional brady.  Interestingly the RR intervals appear pretty similar regardless of whether P waves are present or not.

The T waves are relatively flattened and I would argue there’s the suggestion of a U wave in the lateral chest leads and aVF.  Several of you questioned hypokalemia, and I agree, this EKG could entirely be consistent with hypoK.  However, let’s return to the vignette.  She’s bipolar and has a tremor.  Can you think of a molecule that like potassium is a +1 cation that has a narrow therapeutic window and could cause a tremor?  This patient is Lithium toxic (hence the battery reference in the title of this post).  Because Lithium is a small molecule dialysis will work for Li just like it will for K.  (And similarly charcoal doesn’t work for either).  Given a normal blood pressure for our patient we admitted her; medicine and cardiology were able to allow the level to drift back down.

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