EXCIMER LASER IRRADIATION OF NONCALCIFIED AND CALCIFIED HUMAN ATHEROMA (248 AND 308 NM WAVELENGTHS)

In order to develop a system of peripheral arterial angioplasty, we carried out an in vitro study to define the quantitative, thermal and morphological characteristics of human-atheroma ablation by excimer laser. A multigas 'Sopra' laser was used. The study was performed by using 248nm, krypton fluoride (KrF), then 308nm, xenon chloride (XeCl) wavelengths. The delivered energy was up to 150 mJ pulse -1, pulse duration was 25ns, and the repetition rate could be adjusted to up to 20Hz. Irradiated tissue segments of the superficial femoral and external iliac arteries were obtained in man during surgical procedures and were both calcified and non-calcified atherosclerotic lesions. Quantitative measurements showed a linear increase of ablated tissue mass depending on the energy delivered. For the same energy, the loss of mass was greater with the 248nm wavelength than with the 308nm. The maximum temperature rise measured at the site of irradiation was 6°C at 248nm and 25°C at 308nm. Histological analysis of the irradiated segments revealed neat and precise ablation without thermal injury of adjacent tissue. At 248nm, this phenomenon was observed for calcified as well as non-calcified atheromas. It is concluded that quantitative, thermal and morphological characteristics of in vitro ablation of calcified and non-calcified human atheroma by excimer laser are compatible to clinical requirements. The results observed at 248nm were experimentally more satisfactory. © 1992 Baillière Tindall.