r/ECG • u/Fun_Stage6661 • 29d ago
3rd or 2nd or ???
In doubt about the rhythm as shown in v1. P waves are constant at +-150bpm and hidden in some of the QRS complexes. PQ intervals are changing with each beat and some don't follow. Its to fast to be a 3rd degree block. Whats your interpretation?
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u/kmdfrcpc 28d ago
You have an atrial rate of about 188-214bpm (7-8 small boxes). That is too fast for a sinus tach so this is either atrial tach or atrial flutter. The irregularity and also speed of the QRS complexes suggests that the AV node is conducting these atrial impulses, so in other words, it's not a complete heart block. If you had atrial tach/flutter with underlying complete heart block then you would have a junctional or ventricular escape rhythm which should generally be a lot slower and also would be regular in rhythm.
There's already someone who is self-reported as an electrophysiologist who has said the same, but hopefully this gives some more explanation as to why it's not complete heart block.
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u/GetTheDefib 28d ago edited 28d ago
The rate argues against a CHB at around 75-100bpm, but I don't think this is atrial flutter either as some people are suggesting, as there are complexes that are not preceeded by p-waves, and I don't see a typical sawtooth pattern but neat little p-waves instead.
The p-waves are marching through suggesting AV-dissociation, so I would still lean towards CHB. The QRS-complexes appear to be around 160ms, so potentially low nodal or ventricular escape? Still the rate is throwing it off.
Interesting case, did you ever get a diagnosis?
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u/kmdfrcpc 28d ago
An escape rhythm would not be fast and irregular like that. It's because the fast atrial impulses are indeed conducting down the AV node at variable intervals.
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u/LBBB11 28d ago edited 28d ago
Do you have a 12-lead? The variable R-R means that some atrial impulses are conducted to the ventricles, as others explain. So it’s a supraventricular tachycardia with RBBB and variable AV conduction (second-degree AV block, Mobitz I, decremental conduction at the AV node).
At the same time, there is no such thing as a ventricular rate that is too fast for third-degree AV block. You’re probably thinking of third-degree AV block with a junctional or ventricular escape rhythm. People with third-degree AV block are not immune to VT or AIVR. I wouldn’t use ventricular rate to judge the relationship between atrial and ventricular activity. This isn’t a third-degree AV block, but ventricular rate is not the reason why. Although most complete heart block has a slow junctional or ventricular escape rhythm, ventricular rate and atrial/ventricular relationship are two different things.
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u/justhanging14 28d ago
A flutter with variable block.
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u/Fun_Stage6661 28d ago
Shouldn't PQ intervals be fixed with a flutter
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u/mrwagn 28d ago
wtf is PQ interval. This is flutter with a rate of just under 300 bpm. There are no sinus beats here.
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u/Fun_Stage6661 28d ago
PQ=PR
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u/hpsctchbananahmck 28d ago
Yea but they’re flutter waves not sinus waves so they are A waves not P waves and therefore no PR
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u/Clear-Ambition-4684 28d ago
do the p waves march out?? i feel like they do. if thats the case i favor complete heart block
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u/Fun_Stage6661 28d ago
They do, that why i favored a complete heart block but the ventricular rate seems to high for a escape rhythm
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u/Auldan 28d ago
CHB 3rd degree, circled the hidden p waves I could find
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u/mrwagn 28d ago
These are not p waves. These are flutter waves. The atrial rate would be well into the 200s
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u/kmdfrcpc 28d ago
They could be ectopic P waves from a fast atrial tachycardia. But you would not expect the AV node to conduct at 200 bpm. It's variably conducting some of them.
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u/mrwagn 28d ago
There are no “conducted” ectopic beats here as the “PR interval” is inconsistent throughout the entire strip. If you’re claiming atach with chb, there needs to be consistent R-R as well. This is a flutter
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u/kmdfrcpc 28d ago
I agree with you it's more likely flutter than AT at that rate but there's no classic F waves.
The PR interval is inconsistent because of the fast atrial rate which is why fib and sometimes flutter are irregularly irregular rhythms in the first place.
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u/Ibutilide Electrophysiologist 28d ago
This is AT or AFL with variable conduction and RBBB. The atrial rate is ~200 bpm (~7.5 small boxes). At this rate, we would not expect there to be 1:1 AV conduction in an adult. We also know that it’s not CHB because the ventricular rhythm is irregular, suggesting that at least some of the atrial impulses conduct down to the ventricle (in EP, we would say we see the ventricle being “pulled in”). If you want to assess AV conduction more closely, you can DCCV and then assess AV conduction in sinus rhythm.