AFib with rvr versus PAT

[june2009]

Last night my patient with end stage muscular dystrophy on vent at hs but weaning for 12 hrs during the day. Only cardiac history htn. Cardiac rhythm sinus tachycardia for days 110's to 120's. All of a sudden goes into what I thought was svt with a rate of 200-210, sustained. Called Dr and gave adenosine 6mg . . .pause...Then back to sinus rhythm and after about 5 minutes back to sinus tachycardia rate 110's - 120's. That's where he stayed. Of course we got an EKG but it was after adenosine so it just showed ST. Consult cardiology, troponin normal, all other labs except crp normal. Crp increased from 0.6 to 1.6 in one day. Nurse reliving me says it's wasn't svt. You couldn't see p waves but the r waves were so close together the p waves could have been hidden. The rate was regular but like I said the beats were so close together it was hard to tell that too. The nurse who relieved me was an er nurse for 20+ years. We work in LTAC, this nurse thinks she's a little better than us lowly LTAC nurses. (Then why are you now working LTAC now right?). The way I see it it could have been afib with rvr, paroxsismal atrial tachycardia, or possibly junctional tachycardia. Either way they are all svt and adenosine was appropriate . . . Yes? The patient had no history of afib. This got me thinking how do you tell the difference between those three rhythms? I went back and looked through old books but they really only show textbook examples that look perfect... Thank you for your input.

[Nalon1 RN/EMT-P, BSN, RN]

So if it was not SVT, what did she say it was?

SVT - any narrow complex QRS with a rate above 150 (or 160 depending on what your reading). Some books say sinus tach is a form of SVT, since it is a tachy rate from above the ventricles.

Was adenosine appropriate, yes, and it fixed it (just like ACLS protocols say).

[AJJKRN]

SVT is just an umbrella term for fast rhythms originating from above the ventricles. The way I understand adenosine is that if the Pt is in sinus tach, adenosine will cause a pause in the rythm and if the Pt is in afib, adenosine will slow the rythm down. But not stop it. (Beware I'm coming off of a 12 hour.night shift!)

[Neuro Guy NP, DNP, PhD, APRN]

Based on your description, it seems to me the rhythm was in fact SVT. You said the R waves were regular, so by definition it could not have been Afib, which is an irregular rhythm (easiest way to tell is an irregular R to R interval). Also Afib is not treated with adenosine. You can treat with IV Cardizem, verapamil (not frequently given, but possible) or amiodarone. Thats just pharm management.

I also.doubt junctional tachycardia because the term junctional would be the AV mode is generating the impulse rather than the SA node, and even in such cases as junctional tachycardia the AV node usually is unable to fire at 200+ beats a minute.

I say all this to say that you were most likely correct in your interpretation as SVT