We’ll be having fun with junctional rhythms and AV pacemakers. This is only because I was able to snag a couple of strips that illustrate these particular rhythms very well. It is rare to get strips as clear as these, and in the case of junctional rhythms, rare (at least for me) to see them all that frequently.
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OK, that out of the way, here goes…
Usually an escape rhythm initiated by the junction (hence junctional…) at the AV node, a back-up if you will for when the normal conduction of the heart is altered. In the strip below, the patient had undergone an EPS and targeted ablation for recurrent atrial fibrillation. They had been throwing everything thing from junctional escape beats, straight junctional, accelerated junctional, junctional tachycardia, idioventricular beats and ventricular pacing. To define:
Junctional Escape Beat: 1-2 beats, originated in the AV node, rate is 40-60 bpm.
Junctional Escape: 3 or mores beats, in other words, continuous junctional beats, again rate of 40-60 bpm.
Accelerated Junctional: 60-100 bpm, where the AV junction has taken over as the primary pacemaker.
Junctional Tachycardia: >100bpm, again where the junction is the primary pacemaker.
Premature Junctional Beats: same as escape beats, but earlier than expected. QRS morphology is usually different as well, like a PVC.
How to spot:
Usually has “normal” QRS structure with either a PR interval <0.12s, a missing P wave (buried in the QRS) or a retrograde P wave appearing after the QRS.
What it means: something ain’t right, as in, “that boy ain’t right.” Something is causing the conduction system to be slightly out of whack, or if you’re a carpenter, half a bubble off. In his case, they had probably caused some collateral damage in the process of targeting his aberrant foci during his ablation, in fact, when asked if he wanted to do anything, the doc pretty much said he was expecting some weirdness from this patient and just to watch him. This can also be caused by drug (dig anyone?) toxicity, ‘lyte imbalances, ischemia, even trauma – we see a lot of rhythm disturbances on our folks post-valve surgery.
So here it is:
We’re looking a accelerated junctional, maybe junctional tach. Notice the 5th and 12th beats look a little different, both I and the tech were calling these PJCs, although they may be PVCs. Also notice the retrograde P-waves popping up after the QRS. The other strip, which I left at work showed the true anarchy of the patent’s rhythm. This looks good comparatively. Hemodynamically, he was stable, just every 10 minutes or so, the tech would come up to the nurse with a new strip to show how his rhythm kept changing. She just kept looking at him like, “uhh, OK, I’m looking at what now?” Like I said, we don’t see this all that much. He was supposed to go back to the lab for a 3rd ablation, but the general consensus among us was that they needed to adjust his pacer and wipe out the node completely, but hey, we’re just nurses, right?
While a full AV pacemaker is not as rare, this particular example was just too pretty to pass up.
Beautiful clear spikes with the correct waves following right behind. I love it when a plan comes together.
I’ll see if I can track down the strip that showed nearly every rhythm the patient was throwing that night. Until then, back to our regularly schedule non-educational programming.