3rd Degree Block with Junctional Escape

[Spatialized]

The other night our tele tech and I were discussing a patient's rhythm and neither of us could figure out the best way to label it and whether or not our interpretation was even correct. Unfortunately I wasn't able to score a strip a strip to illustrate what I'm talking about, but will try to describe it as best as I can.

The patient was having occasional runs of apparent 3rd degree block. P-waves marched and were not related to QRS complexes, with P-waves on top of QRSs. Atrial rate was about 90, ventricular rate was in 70-80. Day shift had been calling it atrial flutter, but there were obvious P-waves during these sequences.

We were kind of stumped because of the classic definition of 3rd degree block has a much slower ventricular rate due to the location of the pacemaker below the AV node. I found some references to 3rd degree with junctional escape rhythms, but again that was usually rates of 40-60, not the 70-80 we were seeing. We settled on calling it 3rd degree block with junctional escape beats - just to give it a name. And this was a infrequent occurrence. They'd run sinus for quite some time, then pop into this rhythm for about 5 minutes then back to sinus.

I'm curious on others' experiences with this. In reality how fast can it go? Could you see the junctional rate into the 80s, or higher? Or is it flutter? I know labels aren't all that important, the patient was stable, but we were trying to find a good way to communicate what the patient was doing.

Thanks in advance!

Tom

[getoverit, BSN, RN, EMT-P]

tom,

ekg's can be weird sometimes, can't they?? one thing you didn't mention in your description was the width of the qrs, i'm assuming it was

a junctional rhythm can have a rate 70-80 or higher, called accelerated juntional or junctional tachycardia depending on how fast it is. often times a 3* avb has a wide qrs coming from the ventricles but that's not an absolute. the actual block itself can occur within the av junction, depending on how high it is (picture a bundle of nerves-the lesion producing the conduction disturbance can be anywhere along it's pathway) it's certainly possible to have a junctional escape in a 3* avb. and if that was the presentation, atropine could potentially improve hemodynamic instability. remember the vagus innervates the av junction but not the ventricles. that's why acls does not recommend using atropine on 3* avb, because you're much more likely to encounter an escape rhythm originating below the junction.

it does sound strange for someone to be going "in and out" of a high-grade avb like that. but very few things are impossible. my grandad was a cardiologist (r.i.p. 9/04) and whenever i'd ask him about some pt we had in a weird rhythm he'd always say "i don't have any idea....what's his pressure?"

v1 is the goldmine lead. the limb leads and i-iii will help you with fascicular blocks/axis deviation/etc but the precordial leads are what i find to be the most helpful in determining the rhythm.

[Spatialized]

Yep, QRS was less than .20s. One tracing we had was from lead II the other was the V lead on a 5-lead telemetry system. No 12-lead was done. We weren't worried, the patient was hemodynamically stable - it's not we were freaking out about it. I'm just trying to add to my knowledge base so when I see it again I can say, "oh yeah it's probably this..." y'know? And it truly was transient in nature, happened about 3 times over the night, no longer than for about 5 minutes tops.

You're pretty much validating what I was able to find on-line, that it could be a transient high-grade block allowing the junction to do its thing. I don't much else about the patient, he was in our step down unit and I was on a different unit. The tech does remote monitoring for them and for us.

Cheers,

Tom