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 (TM) XPS (TM) 180 W, 532 nm lithium triborate laser and MoXy (TM) fiber in a survival model of living dogs. We compared these findings with those of the existing GreenLight HPS (TM) 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 mu m (vs the existing 600 mu m 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.