Photoselective Vaporization of the Prostate Using a Laser High Performance System in the Canine Model

Abstract

Photoselective vaporization of the prostate with the 80 W KTP laser has been shown to be an effective and durable therapy for benign prostatic hyperplasia. We investigated the new, more powerful GreenLight HPS(R) High Performance System laser in the canine model as a more rapid treatment for benign prostatic hyperplasia. Five male beagles underwent general anesthesia and laparotomy. Photoselective vaporization of the prostate was performed in antegrade fashion through a suprapubic cystotomy at 40, 80 and 120 W at 3 firing periods (5, 10 and 20 seconds). Photoselective vaporization of the prostate was performed for each power and time combination in stationary fashion at unique locations. Prostates were harvested and histopathological analysis was performed. Mean vaporization and coagulation depths of each laser setting were determined and compared using ANOVA. Vaporization depth was 4 mm to full thickness. Coagulation occurred 1.2 to 2.5 mm deep to the vaporization zone. Increasing laser power appeared to increase depth of vaporization with equivalent or less coagulation depth and increasing the lasing duration behaved similarly. Microscopic pathological evaluation revealed damage to adjacent tissues in areas of full-thickness vaporization at the longest exposure times. The HPS laser is capable of greater power than the 80 W KTP system. HPS laser beam effects appeared more optically confined than those of its lower power brethren. It consistently vaporized more tissue during a given period while maintaining a 1 to 2 mm rim of coagulation, like its predecessors. The HPS should be applied carefully due to the ability to rapidly create full-thickness tissue vaporization.