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 w ith the ProLase II lateral-firing laser fiber in the canine prostate w ere evaluated. Fourteen male dogs, aged 3 years and older with establi shed benign prostatic hyperplasia, underwent endoscopic ablation of th e 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 un derwent a sham procedure and served as a normal control. Prostates wer e examined grossly and histologically at 48 hours, 2 weeks, 4 weeks, o r 8 weeks post-treatment. The cross-sectional diameter and volume of t issue ablation were measured in each prostate, Histological studies of the extent of thermal injury to the prostatic tissue and the course o f healing of the prostatic urethra were performed. The mean cross-sect ional 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 di fference in diameter or volume of tissue ablation was noted between va rying power settings. Histological studies showed extensive tissue nec rosis 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 wa s observed. (C) 1994 Wiley-Liss, Inc.