This is a prospective observational pilot study of suitability of autonomic monitoring via the VU-AMS device for prediction of neurocardiogenic syncope (NCS) in children referred to cardiopulmonary exercise testing (CPET) for a diagnosis of syncope. The study population is children referred for CPET to evaluate for neurocardiogenic syncope. The purpose is to describe autonomic function during rest and exercise and determine the positive predictive value of autonomic function measurements against the gold standard for diagnosis of neurocardiogenic syncope, the CPET. Children presenting for CPET with chest pain or who are status post orthotopic heart transplantation will serve as positive and negative controls respectively.

Inclusion Criteria:

• Parent/Legal guardian able to provide informed consent
• Verbal participant assent
• Undergoing clinically indicated CPET.
• Diagnosis of either syncope, chest pain/dyspnea or status post OHT
• Participant willing and able to participate in study procedures
• Age 7-24 years

Exclusion Criteria:

• Participant unwilling or unable to participate
• Contraindication to adhesive placement, eg, epidermolysis bullosa
• Cancellation of the subject's planned CPET procedure.
• Tracheostomy tube presence (this will prevent proper placement of impedance cardiogram lead)

The study will enroll participants scheduled to undergo clinically indicated CPET procedures.