Postural tachycardia syndrome (POTS) is a relatively common condition affecting mostly
otherwise healthy young women. It is the cause of significant disability and an impairment in
quality of life. These patients have high heart rate and symptoms during standing. Many of
these patients are disabled and have a poor quality of life. The sympathetic nerves are part
of the nervous system that helps to maintain normal blood pressures and heart rates during
activities of daily life. The purpose of this study is to determine the importance of
sympathetic activation as a cause of orthostatic symptoms. The investigators will assess the
effects of a blood pressure medication (Moxonidine) on the symptoms during standing.
Moxonidine lowers sympathetic activity. The investigators believe patients with high resting
sympathetic activity might benefit from Moxonidine. It might reduce high heart rate and
improve symptoms during standing. This study should help clinicians and the growing
population of patients with POTS gain a better understanding of this disorder and find more
personalized treatment.