# Regular AFib?



## GoodLifeMedic (May 18, 2012)

So I got in a debate with my paramedic instructor today regarding AFib and its regularity.  (I've been a practicing Intermediate for awhile and are in the process of bridging)  The way I first learned AFib, its the absence of a p wave or an erratic isoelectric line prior to the QRS complex, it is USUALLY irregular-irregular, however I have seen some very regular AFib's before.  We disagreed over a practice rhythm which I thought was Afib because there was a slight wander to the baseline and the rate was 150bpm (at which I would still expect to see p-waves if they were there) but my instructor said it was SVT because it was regular.  

I'm not contesting that specific rhythm, she's the instructor, but it got me thinking about interpreting AFib, especially in regards to distinguishing it from SVT's.  Using rhythm as the definitive differentiation between AFib and SVT seems problematic to me since although it is usually irregular you CAN have a regular AFib, which means you can't differentiate SVT and AFib off of rhythm alone.  

Thoughts?


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## Aidey (May 18, 2012)

What other criteria was she using to call it SVT?


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## GoodLifeMedic (May 18, 2012)

Rate and rhythm.  Granted it was a close calls and we were splitting hairs on this particular strip.  But SVT right around 150 that ive seen is still usually slow enough to see p waves if they're there.  I thought the baseline was erratic looking and she said that was just artifact, which it could have been.   My issue though was that she said it was regular so it couldn't be Afib and I dont think thats true.


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## Aidey (May 18, 2012)

What about the rhythm was making her call it SVT?


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## GoodLifeMedic (May 18, 2012)

It was a fairly regular, narrow QRS complex with rate between 150-160bpm and no P-waves were present, pointed T wave but there was a return to isoelectric line briefly before the next complex, which looked to me like it wandered some (either artifact or fib).  Her main arguement was that based on rate and the fact that it was regular it was SVT and she said that what I was seeing must be artifact because it was too regular to be AFib.


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## Aidey (May 18, 2012)

OK, your teacher is an idiot. 

SVT is a class of rhythms. It includes A-fib, A-flutter, MAT, sinus tach*, and several reentry tachycardias. Basically any rhythm over 100 bpm that originates above the ventricles, hence the name, SVT. Generally, when people say SVT they referring to the reentry tachycardias. 

A RATE OF 150 DOES NOT AUTOMATICALLY MAKE IT A REENTRY TACHYCARDIA!!! 

A very rough guideline is that a reentry tachycardia has a minimum rate of 220 minus the pts age. These rhythms bypass the AV node and are not slowed down, which is why they have a rate above the max sinus tach rate for the pts age. 

It is possible to have A-fib that appears very regular, but these pts are usually medicated to achieve that. They are the ones who have A-fib at a "normal" rate. A-fib at a rate of 150 is not a controlled rate, and it is doubtful it would be regular. However, the faster the rhythm the more regular it looks which is why you may need to measure the R to R several places to be sure.


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## GoodLifeMedic (May 18, 2012)

Ahhh, I tried to attach a picture of the strip but it won't let me for some reason.  Thanks Aidee, thats what I thought.  Like I said, this particular rhythm may have been SVT, its possible that I was reading too much into this particular rhythm.  I just wanted to know what you thought about Afib vs SVT in general, and whether judging off of regularity alone was a good way to rule out AFib.


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## Aidey (May 18, 2012)

*facepalm*

Yes, it was SVT. It was a tachycardia originating from above the ventricles.


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## mycrofft (May 18, 2012)

There's the disease and the rhythm. I can have A fib (I do, as a matter of fact) and thanks to meds and foreswearing caffeine abuse*, I can be quite regular for short periods, up to about five minutes at a time. My pulse rate remains above 120/min though.

Now, during this periods, do I "have" A-Fib? The disease, yes. The rhythm, no, it records electrocardiologically as a SVT. 

And as to regularity of any fibrillation: by their nature, they are not, electrographically. You might palpate something like a regular pulse, but there are ineffective quiverings going on in between; when such a pulse coordinates with a strong "quiver", the result is a palpable "THUNK".


*Caffeine abuse: try eight of twenty ounce Mt Dews per eight hour work shift? Plus coffee in the AM


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## FLdoc2011 (May 18, 2012)

Post a pic of the EKG if you can.

Common things being common I wouldn't think if afib as first diagnosis of a regular (regular R-R interval) narrow complex tachycardia at 150bpm.   That's kind of classic for aflutter. 

Can certainly have afib that's regular, usually that's someone with more significant AV nodal disease, a high grade nodal block or on dig.  That's kind of one of our board type questions.... You have a pt in afib but very regular (as opposed to paroxysmal afib where you caught them in sinus) you should think of possible dig toxicity.


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