Atrial/inappropriate sinus tachycardia/pauses

[Emcat]

Hello, i am a 26yr old non smoking female, weigh 125 pounds, 5' 7" and until 6 month ago in v good health, regular runner and was training for a half marathon.
Well last July I had been for a 90 min run and a couple of hrs after i started having horrendous palpitations (160 bpm), went to the ER and was kept in for a few days whilst I had an Echo, treadmill test, various ecg's. (All normal). The whole of this week i had awful chest pain, felt incredibly fatigued, and every time i moved an inch my heart rate bounded 100+. I was eventually told i was having anxiety attacks even tho i hadnt been stressed in the slightest. A week later i went to see a cardiologist who said i had had Atrial tachycardia, and sinus tachycardia and that i had most likely had a viral myocarditis or had an electrolyte inbalance (all my bloods were fine tho). SInce then I have also had an MRI scan which showed fibrosis on my heart (my cardiologist says i dont have enough for it to be a big deal and that should shrink in time). I was put on Ivabradine 5mg a day as was still having daily sinus tachycardia with any exertion, and i am deemed unsuitable for bet blockers as my bp is on the lower side.
So fast forward 6 months, and I am still having probs, i had a bad episode of tachycardia in Dec where my hr reached 180, my doc said it would def have been atrial tachycardia if it were that fast and that they could cure that with ablation. I also have incomplete right bundle branch block, which in the first few months would not be there at all and other times would, it currently seems to always be on my ecg's. And I am having episodes where I feel my heart "pauses" in between beats, I know in these instances they are not PVC/PAC's aS I have those also and with the pauses i do not have the thump and headrush that you have with ectopics. Also, I have having frequest feelings of dizziness, difficulty breathing, and a few months ago i had what felt like an electric zap through the head. My cardiologist thinks my latter symptoms are caused by my constant worrying about all this and so anxiety, but i am not convinced,
so my questions are,

1. Are inappropriate sinus tachy and atrial tachy two separate probs? Were both caused by the so-called myocarditis? Would ablation get rid of one but not the other?
2. My cardiologist says it is unusual that I have incomplete right bundle branch block that comes and goes, but that he is not concerned by it, given the fact that I have experienced what feel like pauses in my hearts rhythm does this mean my sinus node could be dysfunctioning? 24hr ecgs show a heart rate of minimum 52 when i am asleep.
3. Wat could my dizziness and difficulty breathing be from? I get it even when my heart is being well-behaved and isnt racing!

Any help at all is appreciated!

Thanks

[is_something_wrong]

1. No, they are not the same. So-called atrial tachycardia is a rapid heart rate originating somewhere else than the sinus node (but still in the upper chambers). IST is a constantly elevated heart rate without any obvious reason that never (except during sleep) is lower than 100 BPM, with severe exercise intolerance. The cause is often not in the heart, but in the autonomic nerve system. Myocarditis doesn't cause IST and (I think) rarely atrial tachycardia. It can be linked to arrhythmias when you exercise, but this isn't necessarily caused by myocarditis. Myocarditis would usually show on echo and EKG.

2. My lowest heart rate during 24h EKG was 38. I don't have sinus node dysfunction. It's easily found on 24h EKG with tachy/brady intermittent and usually runs of atrial fibrillation. IRBBB is a normal variant, forget it if your cardiologist isn't worried.

3. Not sure. Is your ejection fraction on echo OK? How certain is the myocarditis diagnosis? It may be "everything and nothing" - as long as your heart function is OK it's usually not the heart. Electrolyte imbalances, hypoglycemia, tense muscles, autonomic hyperactivity, anxiety.. Your doctor must answer this.

[Emcat]

Hi Jodie - thanks forgetting back to me!

Well I havent told him about all these pauses yet, but am seeing him this week so will do then. Altho i did have 2 episodes one afternoon a few weeks ago when I had all the feelings associated with ectopics, felt like the air was knocked out of me and i felt i was going to faint, then my heart beat resumed to normal, i think that could have been one of these pauses, when i mentioned it to my cardiologist he said it could have just been an exagerrated Sinus arrythmia. I worry about it being a sinus pause tho. And given the I have incomplete bundle branch block that comes and goes, i worry that my conduction system is a bit flawed.

How long have you been having ur pauses? Does ur doc give you an explanation for them when he says not to worry? Easier said that done!

Do you know what triggered ur Ist 20 yrs ago? About ur PVC's, i dont think that 282 in 24 hrs is considered a lot, I think u have to have about 15,000 for them to be concerned. And i dont think ur body would become so used to beta blockers that they would stop working as surely they would keep upping the dose? I wonder whether to start taking beta-blockers but I have bad circulatioon in that my feet and hands get quite white in winter so not sure if they would exacerbate this!

Reassuring to know that you had the same dizziness and breathlessness when u were suffering from anxiety, I too get the lightheaded and spaced out feeling, hard to attribute it to anxiety tho when imakes u feel so out of it!

Take care

Emma

[jkfrench]

'And I am having episodes where I feel my heart "pauses" in between beats, I know in these instances they are not PVC/PAC's aS I have those also and with the pauses i do not have the thump and headrush that you have with ectopics.'

This describes what I sometimes get as well.  My heart beats normal and then just pauses before a beat and then beats and pauses again.  Usually happens 2 or 3 times in a row and then dgoes back to normal rythym.  I can also tell the difference because I get pvc's and I do not feel the early beat prior to the pause.  I have been told that it could be the timing of the early beat.  Sometimes it comes so soon that you don't feel it.  However there isn't any thud after the pause either so it doesn't make sense to me.  

I have had all the tests and my doctor just doesn't seem concerned.  My last holter showed 288 pvcs which to me was a lot.  They have been acting up again and it is making me crazy.  I take atenolol and I decided to up the dose to see if it would help and I'm hoping that it has.  I now take 1/2 of a 25mg at night and 1/4 of the pill in the am.  So I am taking 3/4 total of a 25mg pill.  I used to just have to take 1/4.  I wonder if your body can get used to the dosage and then it doesn't work as well.  I have taken the 1/4 for 20 years because when I was your age, I had the same problems as you.  IST - My heart would just race if I raised my hands in the air.  It has been clocked at 220 beats per minute and I was lucky enough to get pvc's thrown into it as well.The atenolol keeps that under control but sometimes my blood pressure does drop to 88/58.  Again, my doctor said not to worry.
If you are feeling dizzy and short of breath when your heart is beating fine, then that is probably anxiety.  I used to get that too.  I would feel off balance and faint.  
Ablations do help with atrial tachycardias.  What did your doctor say when you described these other type of pauses to him?  Mine just said not to worry.  
Jodie