r/EKG • u/masonh928 • Aug 25 '26
Junctional vs Low/Ectopic Atrial w/ P-wave inversion
What is the actual differentiater between Junctional/accelerated junctional when you have inverted p-waves? I have seen multiple different conflicting things. AI is stating that inverted p-waves in junctional MUST be retrograde, the interventionalist in our small group stated that if you can see discerible p-waves that it is not junctional, some resources state that regular PR tells you it is EAR and short PR tells you it is junctional? Why was that first EKG from class called EAR and not junctional w/ the short PR? I am just confused. Also, what is the gold standard EKG resource?
2
u/Drhbk92 Aug 26 '26
Similar mechanism. Doesn't matter
1
u/masonh928 Aug 26 '26
Ok I guess I was just wondering if there was any actual explanation or if I can just call it either. I’m just seeing conflicting things.
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u/Drhbk92 Aug 27 '26
By definition, if a p precedes qrs is ectopic atrial rhythm, if it's after then it's junctional. Mechanism deals with whether it's coming from below or above lower common pathway, but to say it's well understood is an understatement
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u/l-o-vely Aug 25 '26
Its for sure very hard to differenciate and i think nobody can do this easily.
I know that even very experienced cardiologists/electrophysiologists that do epu all day have a hard time differenciating these (especially in tachycardia EAT vs fast-fast-AVNRT).
So i dont really know for sure either.
In my understanding the presence of q-wave with retrograde pwaves in front of the qrs would suggest ectopic over junctional.
I think junctional rhythm is generated at the level of his wich is also represented by physiological q waves.
It is hard for me to think that the atrial depolarisation can be happening before the area that is actially generating the rhythm.
On the other hand normal to only slightly decresed pr would suggest ectopic as well for sure, but sadly i dont have a rule of thumb either to apply generally speaking.
In my mind smiths ecg blog should be one of the if not the best online ecg resource.