S.Arrythmia Vs PACs

  1. So twice, I have come across a situation in which I'll have an EKG strip I'm trying to interpret. Some nurses will say it's sinus arrythmia and some say they're just PAC's.

    The rhythm is definitely irregular. There seems to be some sort of pattern to it. All the complexes (p and QRS) look the same. From my understanding, sinus arrhythmia isn't seen very often and it usually increases in rate with inspiration and decreases with expiration (or vice versa)..but I've learned it goes with your breathing. This rhythm didn't do that. And I've also thought that with PACs, the complex or the p-wave may look different. And I wouldn't think that there would be a constant and consistent pattern with PACs... ?

    Maybe I'm missing something or interpreting wrong? Or is it just one of those things that you don't really know, hehe. I mean.... You ask 3 different cardiac docs, and you get 3 different interpretations.
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    Joined: Apr '06; Posts: 172; Likes: 12


  3. by   AnnieOaklyRN
    PAC will have a different p wave morphology and since they are premature they will come sooner than you expect the next beat. They can be patterened, but that is unusual. If it is sinus arrhythmia all the P waves should look the same since they are comming from the sinus node. Hope this helps

  4. by   ghmccart
    PAC should have a compesetory pause
  5. by   danh3190
    Sinus arrhythmia isn't that uncommon in kids. Usually it's regularly irregular, i.e. it speeds up and slows down and speeds up etc. A lot of time the change in rate is tied to respiratory rate but I don't know if it always is.

    PACs are usually random. They have a P wave that's often different in morphology. Sometimes if the PAC is near the preceeding complex you can't see the P wave because it's buried in the T, but then the T wave looks different.
  6. by   UM Review RN
    There are rhythms that are "regularly irregular."

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