Abstract
An applicability of pulsed Ho:YAG laser and continuous-wave uv Ar laser for the laser angioplasty was studied by investigating an ablation characteristics of these laser irradiations in saline in vitro. We selected Ho:YAG laser in it region, and Ar laser in uv region for therapy laser, since these laser lights have large absorption for vascular tissues (30-70cm-1), and can be used SiO2 glass fiber for laser angioplasty. We employed a SiO2 fiber of 200μm in core-diameter, with 0.33 to 3.82kW/cm2 in intensity at the end of the fiber. The specimens were human abdominal aorta, including fibrous fatty plaque and calcified plaque. The ablation for Ar laser had a sufficient ablation energy efficiency with a good selectivity for yellow plaque. The ablation for calcified plaque using Ho:YAG laser had three times as efficient as soft region. Both laser irradiations could create sharp ablation hole. Ho:YAG occurred with the dissection at high fluence irradiation. Therefore, we determined applicable ablation ranges, 0.2-0.4kJ/cm2/Shot for Ho:YAG laser, and 1.0-2.5kW/cm2 for Ar laser. Comparing these characteristics between Ho:YAG and uv Ar laser performance, we conclude that Ho:YAG laser may be one of proper choice for all kind of vascular tissues, and Ar laser may offer the best performance for ablation without calcified plaque.
