Laser treatment of vascular skin lesions, such as port wine stains, has been attempted with a myriad of laser systems. Early therapeutic efforts resulted in unacceptable scarring that was attributed to unselective heating of tissue. Understanding the mechanisms of laser-tissue interactions lead to the clinical application of pulsed lasers which selectively target the vasculature and leave the surrounding tissue thermally unaffected. Despite these advancements, the optimum laser pulse duration has yet to be investigated. Modeling predicts that a pulse width of several milliseconds would be ideal. Flashlamp-pumped dye lasers (pulse width = 0.4 ms) create pulses which are too short to avoid bruising, or purpura, localized to the irradiated spot. Purpura is a result of vessel disruption and is not a desired clinical or cosmetic endpoint. Continuous wave lasers (exposure time > 30 ms) result in scarring due to overheating the vessel. Laserscope proposes to develop a solid state laser capable of generating pulses between the range of one and ten milliseconds. This laser is a modification of a surgical laser currently manufactured by Laserscope. As part of this study, the laser's effectiveness at coagulating vessels in an animal model will be compared to that of the flashlamp-pumped system.
