title: An endoscopically implantable device stimulates the lower esophageal sphincter on demand by remote control: a study using a canine model.
abstract: OBJECTIVE
  Implantable microstimulators (IMS) have been used in a variety of medical conditions. Selective stimulation to increase lower esophageal sphincter (LES) pressure may be useful in the control of gastroesophageal reflux disease. We evaluated on-demand stimulation of the LES with an endoscopically implanted microstimulator.
  
  
  METHODS
  We performed acute experiments in three 30-kg dogs. After LES manometry, a 3.3 mm x 28 mm microstimulator (the Bion) was implanted into the LES. Manometry was repeated with and without IMS stimulation to record the changes in LES pressure. Stimulation amplitude was varied from 3 mA to 10 mA, with a fixed frequency of 20 Hz and a pulse width of 200 microsec.
  
  
  RESULTS
  The mean LES pressures prior to IMS implantation in the three dogs were 13.0 mm Hg, 5.0 mm Hg, and 14.9 mm Hg. The mean pressures were not significantly changed by IMS placement. There were no documented changes in LES pressure when the amplitude of stimulation was less than 8 mA. After stimulation of the IMS at a setting of 10 mA in dogs 1 and 2 and at 8mA in dog 3, however, the resultant LES pressures were 62.1 mm Hg, 35.1 mm Hg, and 26.8 mm Hg respectively, more than three times higher than post-implantation baseline levels (P < 0.02).
  
  
  CONCLUSIONS
  The LES pressure can be increased using an on-demand microstimulator. The implantation procedure is minimally invasive, represents a novel therapeutic approach to gastroesophageal reflux disease, and may have therapeutic potential for other gastrointestinal motility disorders.
authors.affiliation: Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: J O
authors.initials: JO
authors.lastname: Clarke
authors.forename: S B
authors.initials: SB
authors.lastname: Jagannath
authors.forename: A N
authors.initials: AN
authors.lastname: Kalloo
authors.forename: V R
authors.initials: VR
authors.lastname: Long
authors.forename: D M
authors.initials: DM
authors.lastname: Beitler
authors.forename: S V
authors.initials: SV
authors.lastname: Kantsevoy
mesh_terms: D000818:Animals; D004285:Dogs; D004599:Electric Stimulation Therapy; D004567:Electrodes, Implanted; D049630:Esophageal Sphincter, Lower / Q000502:physiology*; D004945:Esophagoscopy; D008365:Manometry; D023421:Models, Animal; D019919:Prosthesis Implantation; D012371:Robotics