The evolution of photoselective vaporization prostatectomy (PVP): advancing the surgical treatment of benign prostatic hyperplasia

The most recent advance in laser technology for prostatectomy is represented by the potassium-titanyl-phosphate (KTP) laser. By doubling the frequency of pulsed Nd:YAG laser energy with a KTP crystal, a 532 nm wavelength selectively absorbed by hemoglobin was created [1]. This leads to radically different tissue-interaction properties compared to older lasers. KTP laser energy is delivered through fluid medium, such as water, into the cell where it is absorbed by hemoglobin which acts as an intracellular chromophore. The cell rapidly heats up, leading to vaporization of tissue. Laser power is confined to a superficial layer of prostatic tissue due to the wavelength's short optical penetration, leading to rapid vaporization and a 1-2 mm rim of hemostatic coagulated tissue. Although continual irradiation of a single point by laser energy usually causes heat to competitively diffuse into deeper tissue layers, thus creating coagulation, the efficient energy transfer of the KTP laser wavelength in conjunction with the cooling provided by the continual bladder irrigation used in the procedure is able to create only a thin layer of coagulated tissue while providing rapid vaporization. These tissue-selective effects led to the use of the KTP laser in prostatectomy being termed, (P) under bar hotoselective (V) under bar aporization of the (P) under bar rostate (PVP).