| Active, not recruiting | 1 | 11 | US | placebo sugar pill, placebo, Pyridostigmine Pill, pyridostigmine bromide, Mestinon, Galantamine Pill, Galantamine hydrobromide, Razadyne, Vagal stimulation, Transcutaneous vagal nerve stimulation, Sham vagal stimulation | Vanderbilt University Medical Center | Postural Tachycardia Syndrome | 06/24 | 12/24 | | |