Photoselective vaporization prostatectomy: experience with a novel 180 W 532 nm lithium triborate laser and fiber delivery system in living dogs.

Purpose: We studied vaporization parameters, and anatomical and histopathological outcomes of photoselective vaporization of the prostate with the novel GreenLight™ XPS™ 180 W, 532 nm lithium triborate laser and MoXy™ fiber in a survival model of living dogs. We compared these findings with those of the existing GreenLight HPS™ 120 W 532 nm lithium triborate laser photoselective vaporization of the prostate in living dogs.

Materials And Methods: Eight dogs underwent antegrade photoselective vaporization of the prostate with the 180 W laser delivered through a new 750 μm (vs the existing 600 μm core diameter), 50% larger, spot sized, side firing fiber. Four dogs were sacrificed 3 hours and 8 weeks postoperatively, respectively. We recorded laser energy and time. Prostates were sectioned, measured and histologically analyzed after hematoxylin and eosin, triphenyltetrazolium chloride or Gomori trichrome staining and compared with a normal control.

Results: Photoselective vaporization of the prostate with the 180 W laser bloodlessly created a 76% larger cavity (mean 11.8 vs 6.7 cm(3), p = 0.014), vaporized tissue at a 77% higher rate (mean 2.3 vs 1.3 cm(3) per minute, p = 0.03) and did so in 37% less time per volume vaporized (0.5 vs 0.8 minutes per cm(3), p = 0.003). Hematoxylin and eosin, and triphenyltetrazolium chloride staining histologically revealed a 33% thicker mean coagulation zone vs that of 120 W laser photoselective vaporization of the prostate (2.0 ± 0.4 vs 1.5 ± 0.3 mm, p <0.005). In prostates healed for 8 weeks postoperatively hematoxylin and eosin, and Gomori trichrome staining showed re-epithelialized cavities with negligible submucosal fibrosis compared with a normal prostate.

Conclusions: GreenLight XPS 180 W 532 nm lithium triborate laser photoselective vaporization of the prostate with the MoXy fiber has a significantly higher vaporization rate and speed with a deeper hemostatic coagulation zone but favorable tissue interaction and healing equal to those of HPS 120 W laser photoselective vaporization of the prostate in dogs.