the Black-throated U warbler

Ok, its real name is Black-throated Blue, but work with me here.

black-throated blue warbler 1123

Today’s EKG is a 70’s y.o. man with palpitations.


Starting with the rate, it’s a little difficult to assess given the irregularity.  I count 14 complexes, 6×14 = 84, making it a normal rate.  (So don’t gestault it as MAT when it’s not tachycardic).  The next knee jerk response to irregularly irregular rates is whether it’s A fib.  Are there P waves?  Starting as always with the rhythm strips, let’s zoom in on the central sections.

20180514_p wavesb


There are P waves, but interestingly there’s about 3 different morphologies and PR intervals.  If it was tachy this probably would meet criteria for MAT.

Have we accounted for all the inflection points?

20180514_U wave

At least one of you called this a Mobitz block and I suspect it was because of this wave.  Is it a lost P wave though?  It would be odd to have multiple P waves and block (though with dig toxicity a lot is possible as some of you correctly observed).  Is there another type of wave this could be?  Let’s come back to that, we’re getting ahead of ourselves.

The QRS is narrow.  There is a suggestion of ST depression laterally and some T wave flattening inferiorly.

Let’s go back to that extra wave.  The rhythm strip is V3, V4 also shows a U wave.  Now we’re starting to get a sense of why the patient’s heart is irritable with mutliple P wave types, flattened T waves, and a U wave.

It turns out his Magnesium was 1.2 and Potassium 3.1.  In all honesty when this EKG was texted to me I guessed that if there was going to be an answer it would be in the lytes but totally missed the U waves until after the lab results came back when they became obvious in retrospect.  Oh well.  Just gotta keep learning.


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