It doesn't sound like the cardiologist understands about P.O.T.S.. Blood pooling and your heart rate going up to compensate so you don't pass out are symptoms of orthostatic intolerance and are present in P.O.T.S. patients.
I don't think a tilt table test while you are pregnant is a good idea, which is one of the main diagnostic tests used for diagnosing P.O.T.S..
The body, as you likely already know being a nurse, has a huge increase in blood supply while pregnant- though I don't know how that would affect things.
I recommend you try lying down for ten minutes. Then take your blood pressure and pulse with an automatic home cuff. Then stand for 1 to 2 minutes. Take your blood pressure and pulse again. Be sure someone is with you in case you feel like you might faint. Take it again at five and again at ten minutes. Tell me what numbers you get?
I went to the cardiologist and have an Echo on the 28th, but the cardiologist told me that he didn't think it was POTS, and my EKG and heart all seem to be normal. I am 26 and he said it was okay if my heart rate is on the higher side while I was pregnant. I dont know how I feel about this because a nurse the high heart rate screams...not safe to me. He said the blood was most likely pooling in my legs and my heart rate is going up to compensate for it not receiving enough blood. The cardiologist said if I work I need to sit down every hour for at least 10 minutes with my feet up. I was like uhhh you really dont understand what I do for a living. I am so frustrated as a nurse because I feel like my OB and cardiologist are dragging there feet about everything. I am also a may graduate so this was my first nursing job so no one wants to hire me unless its a physically demanding nursing job. It's so frustrating. My work gave me a leave of absence but I still don't know when I'll be able to go back. I love nursing and did a nurse externship for 2 years while in school so I am not completely new to the nursing world but I just wish someone would hire me where I wouldnt be on my feet 24-7.
Weird. I am also a nurse with POTS that manifested when I was 16 months pregnant. I was in the exact same situation you are in now. I just found this site this am and decided to go to the forums to maybe get more help and insight and stumbled upon your post.
I started having tachycardia, was prescribed Metoprolol, and told it would probably go away after the baby was born. It didn't. I saw a cardiologist, who ordered a tilt table test. It did show that I had Syncope (which is a symptom of POTS). I am now on Pindolol to control the tachycardia. It has been 3 years now, and I still have debilitating symptoms. My symptoms are worse when the barometric pressure changes. I can get by, but there are a lot of days I don't feel well enough to do physical activity. I am a hospice nurse, so work is actually easier than being at home taking care of the kids and the house since it is not physically demanding. I only work PRN because I never know what my day will be like until I get out of bed. I also have Chiari, so I have other symptoms to deal with as well that add to it and make things worse.
I hope your tachycardia will resolve after you have your baby. If not, there's all kinds of nursing jobs out there that do not require a lot of position changes and physical activity! Hope this helps.