Insight into mechanism of neodymium: yttrium-aluminum-garnet laser prostatectomy utilizing the high-power contact-free beam technique.

OBJECTIVES: The objective of this study was to define the actual mechanism of neodymium: yttrium-aluminum-garnet (Nd:YAG) laser prostatectomy achieved with the previously described contact-free beam technique using the Ultraline delivery system at high-power settings.

METHODS: Transurethral Nd:YAG laser application was performed with the Ultraline side-firing laser fiber in canine and human prostates. Total or radical prostatectomy was performed after laser treatment to examine and measure laser tissue effects produced using the contact-free beam technique.

RESULTS: Minimal actual tissue evaporation or vaporization was noted in either the canine or human prostate using this technique. The extent of tissue vaporization achieved was probably insufficient to produce clinically significant voiding outcomes acutely or chronically. However, this technique, using the Nd:YAG laser, produced excellent tissue coagulation and necrosis, similar to other laser delivery systems and reports dealing with laser coagulation prostatectomy.

CONCLUSIONS: The primary mechanism accounting for therapeutic efficacy of the contact-free beam technique for Nd:YAG laser prostatectomy utilizing the Ultraline delivery system at high-power settings appears to be tissue coagulation with subsequent necrosis and slough, rather than tissue vaporization. This is consistent with the known tissue effects of the Nd:YAG laser wavelength in other systems.