Investigation of photoablation of atherosclerotic plaques by laser radiation

A study was made of the mechanism and products of ablation of atherosclerotic plaques and arterial walls by laser radiation of wavelengths 308, 539, and 1078 nm at energy densities 0.5–8 J/cm². Visible and infrared radiation were found to have a tissue damage threshold of 3–4 J/cm² and the process was "explosive" involving ejection of large fragments. Ultraviolet radiation resulted in "soft" ablation of tissues throughout the investigated range of energy densities with the minimal effects on the underlying layers. The specific energy of ablation in air was  1.1 ±  0.3 kJ/g and the effective quantum yield of volatile products in vacuum was   0.8 ± 0.3. The quantum yield of lipids and their photoproducts was approximately the same at all the wavelengths and did not exceed 10^–3. The results obtained confirmed the photochemical mechanism of ablation of tissues by XeCl laser radiation.