Having episodic heart rates up to the 160's with symptoms is never normal, especially in someone at such a young age (unless you are exerting yourself such as exercise). There are a number of conditions that can cause extremely fast heart rates. The usual steps taken to understand what is going on includes a baseline ECG, blood work, and a good history and physical. A holter monitor is indicated in order to catch the arrhythmia and determine whether it is truly sinus tachycardia or another condition that can cause a fast heart rate (AVNRT, atrial tachycardia, atrial fibrillation/flutter, etc). If a short-period holter does not reveal anything, then a longer period may be warranted with a loop recorder. Either way, I would recommend being seen by an electrophysiologist who is trained in these types of conditions. If it turns out that there is no underlying conduction abnormalities, then other possibilities should be excluded including metabolic causes such as hypothyroidism, etc.
Thank you very much for replying. I have been seeing an electrophysiologist at Mayo Clinic. He was the one who put me on the 5 week heart monitor. He said that my heart looked fine and that it was something else causing the tachycardia. My thyroid is fine, all blood work/urinalysis have come back normal, all ECG & Physical's have come back normal as well. Ultrasound of legs to check for blood clots-normal/chest cat scan with contrast-normal. When my HR rises my blood pressure does not change-which is why the neurologist cancelled out POTS. I have seen a neurologist/ rheumatologist/ gastroenterologist. They just do not understand why this has happened and what is going on.
** I did go off of BC two months prior to all of this happening, could it possibly be hormone levels unbalanced?
I have done more research and have come across Lyme disease and mono. I seen to have quite a bit of the symptoms mentioned on Lyme disease and did have mono when I was in highschool. Do you think that has anything to do with causing sinus tachycardia? I have also notice about once a month I get flu- like symptoms..... Please Help :)