The Impact of Improved Vagal Function on Periaqueductal Gray Connectivity

Inclusion Criteria: * Age 18-50 years * Diagnosis of POTS, orthostatic intolerance (with or without syncope), syncope, or near-syncope * Can speak and read in English * Upcoming new patient VCU Comprehensive Autonomics Center clinic visit scheduled at least 1 week in the future Exclusion Criteria: * Inflammatory arthritis, connective tissue or auto-immune disorder * Any chronic neurological disorder besides POTS, orthostatic intolerance (with or without syncope), syncope, or near-syncope * Patients who have already had a new patient clinic visit where they were exposed to breathing exercise education * Evidence of unstable medical disorder, such as kidney (rising creatinine, or end-stage renal failure) or liver impairment (rising AST or ALT, or end-stage with coagulopathy), poorly controlled significant cardiovascular (CHF), respiratory, endocrine (diabetes - A1c \> 9 - or untreated thyroid dysfunction) or uncontrolled psychiatric illness (such as untreated depression, psychosis, etc.) * Neuropathy, central nervous system disorder (e.g., Cerebral palsy, developmental delay, seizure disorder, MS, stroke, etc.) * Treatment with a drug or medical device within the previous 30 days that has not received regulatory approval * Use of hormones (except insulin, thyroid replacement or oral contraceptives, which will be carefully documented) * Current substance or alcohol abuse * Any major surgical intervention with general anesthesia in the last 60 days and minor procedure, such as…