supraventricular bigeminy?
First Glance:
From across the room it looks like supraventricular couplets.
Discussion:
The QRS’s are narrow. We really can’t see anything identifiable as a P wave we could hang our hat on. All we know is this is a supraventricular rhythm with grouped beats of 2. Generally this is a sinus beat, followed quickly afterwards by a PAC.
Honestly, however, we can’t tell where these beats are coming from without any useful atrial data. Maybe one or both of them is coming from the AV node. This could be flutter or atrial tach with a high grade variable block, or some unusual sinoatrial block, or a second degree AV block, or maybe the sympathetic tone is up and we are actually seeing escape beats, not premature beats. Who knows. All we can be sure about is that it is a regularly irregular rhythm that is paced from above the ventricles.
The EKG trace dives off the chart halfway through, and if the first half was all we had we might even wonder if this was truly regularly irregular. Maybe it was just a little slice of afib that looked like couplets. However, the lower (arterial) trace shows a monotonous couplet rhythm even when the EKG is lost.
About that arterial line: we can see that the second beat of each group achieves a lower systolic peak, which is most consistent with decreased preload. That might support the second beat being either a junctional beat (ie: with no atrial kick to augment the diastolic filling) or a premature beat of any type that didn’t allow sufficient time for the rapid-filling phase. The early beats don’t really come all that early, so I’d lean towards PJCs unless this patient has tricuspid stenosis or something fancy like that.
If we cared to crack this case, we might flip through some other leads looking for better P waves. If the artifact makes it too difficult to see P’s, you could look at the CVP trace which might reveal A waves suggestive of PACs.
Regardless, the point is that as this person’s rate speeds up, the MAP per beat goes down. You can see visually how bigeminal rhythms do not necessarily pump as much as the same number of evenly spaced sinus beats per minute, and you can imagine further how the BP would drop with a rapid tachycardia.
Final Impression?
Supraventricular couplets with a ventricular rate of 78 bpm.
Management implications:
Nothing particular. The rate is fine and these are supraventricular beats. The MAP is maintained at nearly 80. If your patient is looking bad with this strip, it’s probably not a problem with the heart.
The Take-home Point:
A regularly irregular rhythm where there is a sinus beat followed by a PAC is called atrial bigeminy. The same followed by a PVC would be called ventricular bigeminy. Two sinus beats followed by a PVC would be called ventricular trigeminy. There is also quadrigeminy, but I have never seen higher numbers written down.
‘Geminal’ beats are counted as ectopy.
Two star strip. The meat and potatoes.