It’s a tired cliché, but true nonetheless, time flies. Time flies and sometimes even when you’re not having fun. But what about when the heart is just flying on the EKG?
Rate. Flying! The complexes are just outside of a big box wide so this is pushing 300, probably in the mid to high 200’s. What’s the rhythm. Sinus rhythm is completely eliminated by the rate. There is no chance an adult has a sinus rhythm this fast. Is it narrow or wide? Sometimes it can be hard to tell because there are a lot of waves crammed into a small section of the EKG. I think the lateral chest leads fairly clearly show flat ST segments (they’re depressed technically) which help us see that the depolarization ends quickly prior to repolarization. The rate is narrow therefore. I asked for a differential rather than a solid answer because there’s probably two rhythms you can make a case for here. The EKG is regular. The classic narrow complex fast tachycardia (usually in the 160-220 range) is SVT. This EKG however is even faster than that range. While SVT is still possible, 1:1 flutter has to be on your differential when it’s going this fast. Where do we best see flutter waves? Inferiorly. What do we see inferiorly? aVF is practically a saw tooth.
We discussed the narrow QRS earlier. Looking at the ST waves there’s clear ST depression laterally. It’s very common to see rate-related depression at very fast rates. A lot of you questioned inferior ST elevation. I agree those segments are elevated, but I don’t think you can argue this is a STEMI until you slow the rate down and see what those segments do. What’s more, the elevation may actually be flutter waves superimposed on the ST segment causing them to be artificially elevated.
So, what do you want to do? Our providers put pads on the patient and gave adenosine. The rhythm strip showed flutter and a few minutes later the patient went into a more typical A fib with RVR.
The ST segments have basically resolved. (Though III still looks a tad suspicious, I’d probably repeat this EKG either immediately or in 10 minutes. There is some artifact but there may be a half mm of J point elevation there. A rhythm strip EKG is another option to try to get a clean segment to analyze that’s sans artifact).
The take-homes from this patient with 1:1 Atrial Flutter? First of all remember flutter waves are best seen inferiorly and can often look like ST elevation. Second, this is definitely a patient you would want pads on if you want to try adenosine (which probably most of us would). While this shouldn’t be a WPW situation with antidromic conduction since the QRS is narrow, the rate is an outlier for SVT so you want to be prepared for other unexpected situations.