The optimum laser source for performing coronary artery laser angioplasty has not been determined. The purpose of this study is to define the most suitable laser source for vaporization of atherosclerotic plaque. Selected coronary arteries from human cadavers are exposed to lasers of various wave lengths and precise real time measurements of thermal diffusion are made by thermocouples and infra-red photography. In addition, well defined gross and histopathological techniques are used to compare the effects of various laser-tissue interactions. Four laser sources have been tested. Argon creates a large thermal injury regardless of pulse duration, number of pulses and energy per pulse. Carbon dioxide caused thermal injury to human arteries similar to argon but this can be minimized by alteration of the natural wave length. The most efficacious laser sources were xenon chloride and krypton fluoride. These lasers can be highly controlled and vaporized atheroma well with minimal thermal effects. These studies provided a basis for acquisition of an excimer laser.
