2. Subject is implanted with pacemaker, implantable cardiac defibrillator, cardiac management product, or a medical device that interferes with the SAS or with which the SAS interferes. This includes, but is not limited to, direct brain neurostimulators, spinal cord stimulators, vagus nerve stimulators (VNS), and cochlear implants. Patients with a vagus nerve stimulator implanted but turned off through the duration of the study may be enrolled, provided their clinical status has been stable for at least one month with VNS turned off.