atrial fibrillation at 60 bpm
First Glance:
From across the room it looks like an irregularly irregular narrow complex rhythm, possibly with bradycardia secondary to pauses.
Discussion:
This is atrial fibrillation. If you look at the baseline, it wiggles around a little in a way that could be confused with an organized rhythm. If you look carefully you can find a few spots where there are seemingly regular wavelets at a rate of around 300 (which might suggest a “fib-flutter” picture) but they peter out quickly and the distinction between fib-flutter and afib is clinically meaningless at the bedside as far as I can tell.
How do you decide how fast this guy’s heart is going? The 300-150-100-75 rule isn’t going to do it. Instead, you need to rely on the monitor (which averages an unknown last number of seconds or beats) or you need to calculate it yourself. The best way with an irregular bradycardia is to count 3-second boxes. These are demarcated on most printed strips with a hashmark somewhere or other- in this case along the top border of the grid. I count 9 beats in 9 seconds, for an average of 60 bpm. The machine read 68 bpm. Close enough.
The longest pause has ten and a half large boxes between beats. That translates (at 200ms per large box) to a 2.1 second pause.
Final Impression?
Afib @ ~60 bpm with 2 second pauses.
Management implications:
The rate in and of itself is not necessarily frightening, but every pt might react differently. For instance, if they are an ancient person with calcified arteries who maintains no diastolic blood pressure without a reasonable heart rate this might cause far more circulatory compromise than a younger person whose elastic vasculature maintains a reasonable Mean Arterial Pressure (MAP) even with HRs into the 30s.
Besides assessing the immediate implications of the rate, you should look into what rate control meds you’re giving.
The Take-home Point:
This patient is AF with borderline slow ventricular response. He needs to be clinically assessed for how he tolerates this rhythm and monitored for more significant slowing or pauses.
One star strip. Students should nail this.