The interaction between excimer laser energy and vascular tissue

Abstract

The effects of XeF1 excimer laser on isolated normal and atherosclerotic aorta were studied. Experiments were performed in flowing water at constant temperature, flow rate, water depth, pulse width (10 nsec), wavelength (351 nm), beam size (1 mm 2) and focal length (50 cm). The number of pulses, the pulse energy, and the pulse frequency were varied, and the vascular tissue was studied histologically. The following observations were made: (1) tissue ablation required a minimum threshold pulse energy and was nonlinearly proportional to the number of pulses and the pulse energy delivered; (2) precise tissue ablation occurred at low pulse frequencies, but changes resembling a thermal process were seen as pulse frequency increased; (3) calcified plaque was more photoresistant than atheroma or normal vessel; (4) excimer laser energy was markedly attenuated by blood; and (5) the time interval between pulses and high peak power are related to the precision of ablation by pulsed excimer laser. It is concluded that excimer laser can rapidly and precisely ablate vascular tissue by a photothermal process.