I had a real doozy come in over the holidays in the STICU as a second year resident. 85 yo F with pmh of HTN, CAD, DM, HLD, and probably a couple of other 85 yo problems. She came in because she fell while gardening. She thinks it’s possible that she tripped over a bush. But all she knows is that she woke up on the ground. She gets admitted to the STICU because she has a very small SHD and needs q1H neuro checks. She arrives the nurse mentions to you that her heart rate is in the 30s. She’s also vomiting and feels super dizzy.
Naturally, you get an EKG.
Maybe it would help if she wasn’t shaking so much? You repeat the EKG.
What the heck is going on?
This patient had the kind of EKG that, in order to read, I started from the basics. I think EKG_2 was the easier one to read since she wasn’t shaking so much. So,
- Rate: 42
- Rhythm: It appears to be sinus rhythm (Bradycardia). There is a p (or at least something I can convince myself is a p wave) before each qrs and the p is upright in II. It looks like there could be some extra P waves present, especially in the middle of this EKG, right in the aVR, aVL, aVF line. More on this under intervals/morphology
- Axis: Up in I, down in aVF = Left axis
- Intervals/Morphologies: Oh boy. let’s start with the obvious, the QRS is wide. If the QRS wasn’t wide, this would be concerning for a STEMI given the elevation in V1 and V2. However, this pattern should trigger thoughts of a Left Bundle Branch Block. Let’s review LBBB quickly:
According to life in the fast lane:
- QRS duration of > 120 ms
- Dominant S wave in V1
- Broad monophasic R wave in lateral leads (I, aVL, V5-V6)
- Absence of Q waves in lateral leads (I, V5-V6; small Q waves are still allowed in aVL)
- Prolonged R wave peak time > 60ms in left precordial leads (V5-6)
So I accept that we have a LBBB, is it a STEMI? I’d say it’s Sgarbossa negative, so no CODE STEMI.
Now what is going on with the p waves? If you look at the rhythm strip at the bottom of II, it almost looks like there are 2 different rhythms. The first 3 beats are close together, then there’s a p wave that doesn’t conduct, then a weird looking QRS, another p that doesn’t conduct, repeat that twice more, then back to the original rhythm with the last 2 beats on the page. Initially I was concerned for some kind of weird PVC, but the beats appear to have a p wave before them, which doesn’t fit with a PVC. Then I used my fancy, back of a piece of paper calipers and saw that the P to P interval is consistent whether there is a QRS or not. This was most consistent with a dropped beat, specifically a second degree AV block type 2, since the PR interval is consistent (I think) in the first couple of beats of this EKG. (Remember, type 1 “warns you” about the impending dropped beat as the PR interval slowly prolongs, where as type 2 doesn’t and the beat just disappears; Type 2 is more dangerous and often needs a pacemaker as it can degrade into 3rd degree). I don’t know why the QRS looks different on beats 4/5/6 and the cards fellow I spoke to gave me a very long answer with words I didn’t understand. He did agree with me that this is concerning for a 2nd degree Type 2 block.
So, final read:
Sinus Bradycardia with a LBBB and concern for second degree AV block Mobitz type II.
This patient got a cards consult and a pacemaker.