title: Selection of electrical algorithms to treat obesity with intermittent vagal block using an implantable medical device.
abstract: BACKGROUND
  A laparoscopically implantable electrical device that intermittently blocks both vagi near the esophagogastric junction led to significant excess weight loss (EWL) in an initial clinical trial in obese patients. The study objective was to optimize therapy algorithms and determine the EWL achieved with a second-generation device at university hospitals in Australia, Norway, and Switzerland.
  
  
  METHODS
  Data acquired during the initial clinical trial were analyzed and subsequently used to select alternative electrical algorithms. In the second trial, vagal blocking using one selected therapy algorithm was initiated 2 weeks after implanting the second-generation device. The patients were followed up for 6 months to assess the EWL and safety, including adverse events.
  
  
  RESULTS
  In the initial clinical trial, vagal blocking algorithm durations of 90-150 s were associated with greater EWL compared with either shorter or longer algorithm durations (P<.01). The second trial enrolled 27 patients (mean body mass index 39.3+/-.8 kg/m2) to evaluate a 120-s blocking algorithm. At 6 months, greater EWL was achieved (22.7%+/-3.1%, n=24) compared with the initial study and first-generation device (14.2%+/-2.2%, n=29, P=.03). In both trials, an association was found between the number of 90-150-s algorithms delivered daily and greater EWL (P=.03). No deaths, unanticipated device-related adverse events, or medically serious adverse events were associated with the device.
  
  
  CONCLUSIONS
  This second-generation vagal blocking device, using a therapy algorithm of 120-s duration, resulted in a clinically acceptable safety profile and significantly greater EWL compared with the first-generation device delivering a wider range of therapy algorithm durations.
authors.affiliation: Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Camilleri
authors.forename: James
authors.initials: J
authors.lastname: Toouli
authors.forename: Miguel F
authors.initials: MF
authors.lastname: Herrera
authors.forename: Lilian
authors.initials: L
authors.lastname: Kow
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Pantoja
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Billington
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Tweden
authors.forename: Richard R
authors.initials: RR
authors.lastname: Wilson
authors.forename: Frank G
authors.initials: FG
authors.lastname: Moody
mesh_terms: D000328:Adult; D000465:Algorithms; D001315:Australia; D001340:Autonomic Nerve Block / Q000379:methods*; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D009765:Obesity / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D011474:Prosthesis Design; D012189:Retrospective Studies; D013270:Stomach / Q000294:innervation; D013557:Switzerland; D013997:Time Factors; D016896:Treatment Outcome; D014630:Vagus Nerve / Q000503:physiopathology / Q000601:surgery*; D015431:Weight Loss