Naomi, that would answer my question, ( My understanding of POTS is that the tachycardia needs to be sustained and happens in the absence of orthostatic hypotension). I definitely have orthostatic hypotension! The longer I stand in one place, the worse I get! I failed the tilt test. It was a miserable test, I resisted the test for a long time, I hate fainting and couldn't understand why I had to "prove it". If I can share my tilt test, here in my small town here it is: I get strapped in, tilted up and in walks the technicians husband. He is a volunteer at the hospital and had just had a colonoscopy and was waiting for her to drive him home. He begins chatting with me, asking symptoms, picks up my chart etc... I wanted to tell him to leave but was busy feeling like crap. In the meantime I am rolling in and out of naususness. He eventually walks out. I ask the technician if I can loosen the straps a bit because they are pushing on my stomach and chest making it hard to breath, she says ok. Then out of desperation, I'm holding a plastic vomit bin, I say to her, if u just tilt me all the way up I promise ill faint. So she does and that is the last thing I remember. When I come to she says, wow, that was quite a show, you threw the pan across the room and were jerking all over the place, and because you loosened the straps I had to support u up until you quit moving. She couldn't capture my heart rate at faint. Her report stated she couldn't capture the reading, the last she had was 90/60 heart rate 68. Because my heart rate never went into tachycardia my dr. Said it wasn't POTS. He put me on fludrocortisone , later beta blockers were added because the holter monitor recorded irregular heart beats. I get stabbing chest pains, palpitations that go into my throat making me temporarily feel like I'm choking and going to black out. My muscles have atrophied over the last 1 1/2 years so my neurologist suggested I go on a beta blocker break to exercise (since my hear rate wont rise). Since I've been off the beta blockers my heart rate zooms up very high, it has never in my life done that, that's why I was wondering if maybe it was POTS. I felt the orthostatic hypotension/ autonomic failure/ neurocardogenic syncope label he gave me fit, but I have lately developed weakness, resting tremors, body rigidity and dysphagia, so he thinks the dysautonomia is heading into Parkinson's or parkinson isms. He put me on mirapex and it took care of the rigidity, and restless leg and my feeling of being unbalanced, but has done nothing for my main complaint : not being able to stand without shortness of breath, fainting, heat intolerance,& headaches, Sorry for the long post, I haven't had anyone to talk to that has any idea what it's like to live in a body like this,