"Prominent" Sinus Arrhytmia w/ "Borderline" changes

[Sabrena]

I'm a 26yo Cauc female who was dx with sinus arryhthmia and sinus tach in 2003 from an EKG showing HR variability from 83-111. In 2005 worsening palpataions and fatigue led my primary to refer me to cardiologist. The stress echocardiogram was negative but there were parts I'm still concerned about: My HR went to 196bpm after 6min only going 4.0mph, this is consistent with my current exercise intolerance ie last time on the eliptical my HR reached 202bpm, and I had to stop. Also, trace MR trace TR, are these considered normal? What was grossly normal was my EF of>65% So with the cardiologist said that my heart was strong but I hadn't grown out of the normal SA that kids typically have with respirations and that specifically mine was more prominent, also if my ST was out of control later on I might need BBlockers. I accepted this and decided that I was going to have to tolerate and get used to feeling the frequent drops and rises of my HR.

About a year ago in Dec 07, I got off night shift, lied down and felt a sudden sinking feeling, then rapid HR and SOB like I was at a high altitiude, I went to the ER. My heart rate was very irreg from 80's to 130's but all sinus. No CP. Sats 98-99, CXR norm, Ddim neg, doc said you have obvious SA, no PE, and this attack looked "caffeine induced" ( I had been drinking alot of caffeine working nights) So I stopped drinking coffee and very rarely have even soda. Then in April 08, I had gone to the gym for this first time since I injured my foot a year before and had to stop due to nausea ,dizziness, and palps. I lied down and after 15 minutes with still no relief I went to the ER, they put me on the monitor and my HR was still 140's, EKG ST, CK 266 obviously from the exercise, otherwise labs WNL. When my HR slowed down the got another EKG HR 84, SA. But I was still nauseated and had Orthostatic tachy so they had me stay and gave me IV Zofran which caused a brief run SVT strip and warm sensation, so they said I was sensitive to the med. Anyhow Doc told me to stay away from aggressive exercising.

Which brings me to now, I've had 2 ER encounters within a month, and both times I was simply sitting at my computer. I was never told I had anxiety or panic attacks, I'm thinking because my HR was never consistently tachy, and it was obviously SA. So I decided to order a pulse oximeter and hopefully catch what was going on if and should it ever occur again. When it occurred again I put on my oximtetry. My HR was irreg from 90's to 130's and again when I felt a sinking feeling the reading dropped off showing no values, then picked up at 52,70's,90's,100's...all the way to 178 within seconds, along with my sats hanging around 94-95% eventually going back to 99%. Again ER, EKG ST with borderline repol w/ st dep/abnorm T. Labs ok, CXR clear, Ddim 1.0, Trop neg. Referred to cards, wore a holter for 24hr, no events but prelim showed SA with prominent HR fluctuation even during sleep.

Again even though results were neg or normal, these things concern me: Last three potassiums 3.1, 3.4, 3.5; Na 132, 134, 135- and this one was very peculiar as I had just finished half a bag of salt and vinegar chips that day. Also all my EKG's have been "borderline" And when looking back I'm concerned about the QTc of .448(HR 112)and .41(HR 84).

These symptoms are interrupting my life and seem to becoming more frequent. I feel like these "borderline" and "prominent" terms might lead to something worse one day. My dad has Afib/flutter, his parents both died from MI/CAD, and my mom's dad had a one time fatal MI in his 50's. The only med I'm on is Yaz for 3months now, before that other BC. I have a follow up appt with the Cardiologist to discuss my Holter results and I want to be prepared with appropriate questions and/or suggestions for further testing. Any input is greatly appreciated, thank you.

[John Kenyon, CNA]

Hello -

"Prominent" SA in an otherwise healthy young person, with symptoms you describe and largely negative findings (those "borderline" things duly noted) is usually due to one of two or three things: you may have dysautonomia, a condition where the autonomic nervous system responds to various stimuli (such as positional changes, exercise, etc.) inappropriately; neurocardiogenic syncope (whereing the barostat receptors malfunction, causing BP to drop inappropriately, with reflex tachycardia intervening to compensate); or sick sinus syndrome (SSS), which involves alternating too-slow with too fast heart rates, and can eventually progress to the point where the patient's heart gets too slow and a pacemaker has to be implanted. However, you also seem to have one of those rather mysterious metabolic problems where potassium levels will not hold despite a normal diet, hydration, etc. This may be related or may be a separate problem, but it certainly would be worthwhile to try treating this first, since patients with arrhythmias (and SA is an arrhythmia) are generally preferred to have something better than the bottom of "normal" or below normal K levels. A time-release form of K probably should be tried for a few weeks to see if this helps correct the larger problem. Low levels of K would explain the T-wave abnormalities.

Your Q-T interval, at least once, was over-long, which can be an acquired problem with too-low potassium levels, so this really should be persued first. If the tachy-brady problem persists after stabilizing K levels,

Neurocardiogenic syncope can be ruled out (or in) via tilt table testing. SSS can also sometimes be determined by tilt table testing, as well as collective observed signs and symptoms, of which you seem to have many. When an adult fails to outgrow the normal pediatric SA, it often is because it has morphed into SSS. This needs to be followed with an eye toward correction, especially if K replacement doesn't correct this particular part of the cluster of symptoms.

I hope this is helpful to you. Please follow up with us as needed. Best of luck to you.