Greenlight Photoselective 120-Watt 532-nm Lithium Triborate Laser Vaporization Prostatectomy in Living Canines

Abstract

Efficiency, anatomic, and histopathologic outcomes of GreenLight HPS 120-W, 532-nm lithium triborate (LBO) laser photoselective vaporization of the prostate (PVP) in a survival model of living canines were studied and compared with the outcomes of the only benchmarked survival study of 60-W 532-nm potassium-titanyl-phosphate (KTP) laser PVP in living canines. Twelve dogs underwent anterograde PVP with the 120-W LBO laser and, 4 each, were euthanized 3 hours (acute), 3 days (early), or 8 weeks (chronic) postoperatively. Laser energy and time were recorded. Prostates were sectioned, measured, and histologically analyzed after hematoxylin and eosin (H&E), triphenyltetrazolium chloride (TTC), or Gomori trichrome (GT) staining and compared with a normal control. LBO laser PVP at 120 W acutely created a 6.7 +/- 3.2 cm(3) cavity, hemostatically, and vaporized tissue 160% more efficiently (mean 1.3 cm(3)/min vs 0.5 cm(3)/min), 500% faster (mean 4.9 vs 29.1 min), and needed 121% less energy (mean 28.8 vs 63.6 kJ) than the 60-W KTP laser. Histologic staining with H&E and TTC demonstrated a coagulation zone of 1.5 +/- 0.3 mm for the 120-W LBO laser, comparable to the 1 to 2 mm for the 60-W KTP laser. H&E- and GT-stained, healed prostates at 8-weeks postoperatively showed reepithelialized cavities with minimal submucosal fibrosis compared with an identically stained normal and the benchmarked KTP laser PVP-treated prostates. Our in vivo canine survival study demonstrates GreenLight HPS 120-W, 532-nm LBO laser PVP has substantially more vaporization efficiency and speed, with equally favorable tissue interaction and healing vis-à-vis those benchmarked for the 532-nm wavelength by KTP laser PVP.