title: Closure of the cystic duct by ultrasonic energy: an electron-microscopic and biomechanical study in man.
abstract: BACKGROUND
  Ultrasonic activated devices are currently used both for sealing of blood vessels and dissection of parenchymal organs. Recently, ultrasonic energy has been used to seal the cystic duct during successful clip-less cholecystectomy, but no study examined the mechanisms of tissue welding by ultrasonic energy or the biomechanical properties of the seal. This was the aim of our investigations.
  
  
  METHODS
  Eight patients (7 women and 1 man, mean age 42+/-7 y) subjected to laparoscopic cholecystectomy had a cystic duct sealed and sectioned by Ultracision; after removal of the specimens, the distal end was processed for scanning electron microscopy and transmission electron microscopy, whereas the proximal end to the gallbladder was used for determination of the bursting pressure.
  
  
  RESULTS
  The bursting pressure of the cystic duct sealed by ultrasonic energy was 168+/-47 mm Hg, well above the maximal pressure of the common bile duct. At scanning electron microscopy, the end of the cystic duct was closed by an amorphous, bundled, dense substance. The section proximal to the end showed destruction of the epithelial layer with dense amorphous bridges connecting the opposite sites of the wall. When the lumen was observed, it was filled with bile microaggregates. At transmission electron microscopy, 2 different findings were evident: (1) coagulative necrosis in the sectioned area and (2) a combination of coagulative necrosis and collagen denaturation in the more distal sections. The connective tissue was characterized by attenuation of collagen birefringence and swelling of fibers and bundles due to shrinkage of collagen.
  
  
  CONCLUSIONS
  Ultrasonic energy can be applied to suitable tissues to obtain sealing of the walls with good biomechanical effects.
authors.affiliation: Department of Clinical Sciences L Sacco, Clinical Institute S Siro, L Sacco Hospital, University of Milan, Milan, Italy. Diego.Foschi@unimi.it
authors.forename: Diego
authors.initials: D
authors.lastname: Foschi
authors.forename: Paola
authors.initials: P
authors.lastname: Cellerino
authors.forename: Fabio
authors.initials: F
authors.lastname: Corsi
authors.forename: Paolo
authors.initials: P
authors.lastname: Previde
authors.forename: Raffaele
authors.initials: R
authors.lastname: Allevi
authors.forename: Emilio
authors.initials: E
authors.lastname: Trabucchi
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D017081:Cholecystectomy, Laparoscopic; D002764:Cholecystitis / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D003549:Cystic Duct / Q000473:pathology / Q000502:physiology* / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D011312:Pressure; D014464:Ultrasonic Therapy