Inclusion Criteria:

• Willing and capable to provide informed consent

• Age 18 or above

• Previously underwent a clinically indicated ARS assessment without complications (including deep breathing, Valsalva maneuver, and tilt table testing).

• Previously diagnosed with OH, Vasovagal syncope, OR control subjects assessed as normal, based on the ARS assessment. Participant enrollment shall be based on the type of diagnosis.

• Willing to complete all required study activities.

Exclusion Criteria:

• Currently enrolled in another clinical trial that might interfere with data collection.

• Subject is pregnant or planning to become pregnant during the study

• Active Implantable Medical Device, e.g. cardiac implantable electronic devices, bladder stimulators, diaphragm stimulators, implantable neuro stimulator, implantable active monitoring devices, implantable active drug administration devices, etc

• Have a prosthetic cardiac valve or previously underwent cardiac valve surgery.

• Known allergy to materials used in the study (adhesive, ECG electrodes)

• Diagnosed with syncope due to cardiologic causes.

• Have had a myocardial infarction in the previous 90 days

• Have been diagnosed with tachycardia that requires current medical treatment

• Have any contraindications for exercise testing, tilt table test, Valsalva maneuver test or deep breathing test (judged by the study Principal Investigator)

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 12/29/2025. Questions regarding updates should be directed to the study team contact.