Like the rest of you, we looked into all 3 of those as well. Johns Hopkins was also highly recommended to us by many doctors- unfortunately we hit an insurance wall there. We got our peace of mind at the National Institute of Health in Bethesda, MD. While it is a major research hospital and the doctors aren't really "treating doctors" I was able to have testing done that showed exactly what was happening in every part of my body when i was having a POTS spell. When i went there, it was specifically to participate in a "propanalol study" however we found through the study that it did work for me, proven through passing a tilt table with flying colors. Dr. David Goldstein was my dr. there, assisted by Dr. El-Dadah- both of whom are wonderful. I can't go see him for check ups or regular visits but we do stay in contact with them via email when things get bad for suggestions. The problem we run into at home is that no doctor wants to treat me. There is so little known about POTS that my cardiologist sends me to a neurologist who sends me to an electro-physiologist- nobody wants to take responsibility!! POTS is very frustrating!!!