title: Impact of Laser Power and Firing Angle on Coagulation Efficiency in Laser Treatment for Twin-Twin Transfusion Syndrome: An ex vivo Placenta Study.
abstract: OBJECTIVE
  To assess the impact of laser power and firing angle on coagulation efficiency for closing placental anastomoses in the treatment of twin-twin transfusion syndrome.
  
  
  METHODS
  We used an ex vivo blood-perfused human placenta model to compare time to complete coagulation using 30 vs. 50 W of neodymium-doped yttrium aluminum garnet laser power and using a firing angle of 90° vs. 45°. Placentas were perfused with pig blood at 5 mL/min. Differences were analyzed using independent-samples t test, Mann-Whitney U test, or χ2 test as appropriate.
  
  
  RESULTS
  Coagulation took less time and energy using 50 W (n = 53) compared to 30 W (n = 52), 11 vs. 22 s (p < 0.001), and 557 vs. 659 J (p = 0.007). Perpendicular coagulation (n = 53) took less time and energy compared to a 45° angle (n = 21), 11 vs. 17 s (p = 0.004), and 557 vs. 871 J (p = 0.004). Bleeding complicated 2 (3%) measurements in the 50-W group, 5 (10%) in the 30-W group, and 3 (14%) in the 45° group.
  
  
  CONCLUSIONS
  In a highly controlled model, a 50-W laser power setting was more energy efficient than 30 W in coagulating a placental vein. A more perpendicular laser firing angle resulted in more efficient coagulation. Furthermore, bleeding due to vessel wall disruption occurred more often with lower power and a more tangential approach.
authors.affiliation: Department of Obstetrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: Akkermans
authors.forename: Loes
authors.initials: L
authors.lastname: van der Donk
authors.forename: Suzanne H P
authors.initials: SHP
authors.lastname: Peeters
authors.forename: Sjoerd
authors.initials: S
authors.lastname: van Tuijl
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Middeldorp
authors.forename: Enrico
authors.initials: E
authors.lastname: Lopriore
authors.forename: Dick
authors.initials: D
authors.lastname: Oepkes
mesh_terms: D000818:Animals; D005260:Female; D005330:Fetofetal Transfusion / Q000601:surgery*; D006801:Humans; D066298:In Vitro Techniques; D017075:Laser Coagulation / Q000295:instrumentation / Q000379:methods*; D010920:Placenta / Q000473:pathology / Q000601:surgery*; D011247:Pregnancy; D013552:Swine
keywords: Laser energy; Laser power; Laser therapy; Placenta; Twin-twin transfusion syndrome