CHARACTERIZATION OF TISSUE EFFECTS PRODUCED BY THE PROLASE-II LATERAL-FIRING NEODYMIUM-YAG LASER FIBER IN THE CANINE PROSTATE

The immediate and long term-effects of neodymium:YAG laser treatment with the ProLase II lateral-firing laser fiber in the canine prostate were evaluated. Fourteen male dogs, aged 3 years and older with established benign prostatic hyperplasia, underwent endoscopic ablation of the prostate using the ProLase II fiber. Subjects were treated at laser power settings of 60 watts (6 dogs), 75 watts (4 dogs), or 90 watts (3 dogs), with a mean total energy delivery of 15,000 joules. One dog underwent a sham procedure and served as a normal control. Prostates were examined grossly and histologically at 48 hours, 2 weeks, 4 weeks, or 8 weeks post-treatment. The cross-sectional diameter and volume of tissue ablation were measured in each prostate, Histological studies of the extent of thermal injury to the prostatic tissue and the course of healing of the prostatic urethra were performed. The mean cross-sectional diameter of tissue ablation was 28.6 +/- 4.7 mm and mean volume of tissue ablation was 8.2 +/- 5.1 cc. No statistically significant difference in diameter or volume of tissue ablation was noted between varying power settings. Histological studies showed extensive tissue necrosis with hemorrhage and an acute inflammatory cell infiltrate at 48 hours. By 8 weeks, total resolution of both necrosis and inflammatory changes with complete re-epithelialization of the prostatic urethra was observed. (C) 1994 Wiley-Liss, Inc.