title: Magnetic retraction in natural-orifice transluminal endoscopic surgery (NOTES): addressing the problem of traction and countertraction.
abstract: OBJECTIVE
  Because of their reliance on the flexible endoscope, most current procedures in natural-orifice transluminal endoscopic surgery (NOTES) suffer from the inability to vigorously grasp and move tissue or to retract organs. We aimed to assess the use of internal and external magnets that might allow the vigorous multiaxial traction/countertraction required in more complicated NOTES procedures.
  
  
  METHODS
  Ex vivo and in vivo porcine model. Study components were: (1) Evaluation of force-distance relationship of this magnetic retraction system using a digital tensiometer. (2) Application of this magnetic retraction system to two procedures in the porcine model: (a) Liver retraction during transcolonic cholecystectomy in five nonsurvival pigs. Procedure time was recorded and compared to historical controls. (b) Mesh positioning for implantation into the anterior abdominal wall for ventral hernia repair in three survival pigs.
  
  
  RESULTS
  Over a distance of 5 cm to 0.25 cm, the magnetic force of our system increased from 3 to 90 gramforce (29.42 to 882.60 mN.) In vivo, the magnet system provided robust liver retraction, shortening the procedure time of NOTES cholecystectomy from a historical mean of 68 minutes (range 42 - 90 minutes; n = 5) to 49.6 minutes (range 33 - 61 minutes; n = 3). The magnetic system also greatly enhanced mesh positioning and stability, and these animals survived for 2 weeks without complications.
  
  
  CONCLUSIONS
  Our basic system provided critical liver retraction during NOTES cholecystectomy and was also instrumental in moving and stabilizing mesh for implantation during NOTES ventral hernia repair. Magnets can potentially provide the vigorous traction and countertraction required to advance NOTES procedures.
authors.affiliation: Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: M
authors.initials: M
authors.lastname: Ryou
authors.forename: C C
authors.initials: CC
authors.lastname: Thompson
mesh_terms: D000818:Animals; D002763:Cholecystectomy; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006555:Hernia, Ventral / Q000601:surgery*; D008280:Magnetics / Q000295:instrumentation*; D009354:Neodymium; D013526:Surgical Mesh; D013552:Swine; D014143:Traction / Q000295:instrumentation*
chemical_list: D009354:Neodymium