[An experimental study of excimer laser angioplasty in vitro]

Intratube thrombus and in vitro intraarterial thrombus and isolated normal pig aortic wall were radiated by excimer laser with wavelength of 308 nm and pulse width of 20 ns. The single pulse energy and the numbers of pulses were varied at the constant beam size and pulse frequency and the results were studied by micrometer measurement and histological examination. The results show: (1) excimer laser can effectively ablate thrombus. With constant total energy (at the range from 10 to 50 J), the depth of vaporized thrombus was nonlinearly proportional to the single pulse energy. But with constant single pulse energy (at the range from 10-100m J), the depth of vaporized thrombus was in linear proportion to the numbers of pulses; (2) if coaxial position of laser beam with blood vessel was maintained, thrombus can be effectively vaporized without arterial wall damage; (3) the incision produced by excimer laser has microscopically precise edges: there is no evidence of thermal injury and adjacent tissue is unaffected. Our conclusion is that excimer laser can be used safely and effectively in angioplasty. It may be mainly by photochemical effect that excimer laser ablates organic tissue.