title: Potential use of holmium lasers for angioplasty: evaluation of a new solid-state laser for ablation of atherosclerotic plaque.
abstract: Tissue effects of the mid-IR Holmium laser (emitting at a wave-length of 2130 nm) were evaluated. This wavelength is attractive because it combines high water absorption and easy transmission through standard optical fibres. The laser was pulsed with pulse durations in the range of 100 microseconds and repetition rates between 2 and 6 Hertz. For all experiments a repetition rate of 2 Hertz was used. The laser beam was coupled into waterfree quartz fibers with core diameters of 200 and 800 microns with an efficiency of 70 and 80%, respectively. Ablation of atherosclerotic plaque has been performed at an ablation threshold of 10J/cm2 for the 800 microns and 40J/cm2 for the 200 microns fibre. Removal of calcified plaque was possible. Ablation efficiency increased in a non-linear fashion with increasing pulse energies. The ablation rate per pulse was approximately 2 mm at energy fluences of 1000J/cm2 for the 200 microns fibre and 1.25 mm at energy fluences of 70J/cm2 for the 800 microns fibre; a further increase in energy densities did not result in higher ablation rates. On macroscopic examination only very limited thermal injury was found in crater adjacent tissue structures. Crater edges were even and did not reveal signs of crater charring or debris in the crater lumen. However, the histologic specimens revealed zones of thermal damage extending 100 up to 1000 microns lateral into adjacent tissue. Thermal damage increased with increasing radiant exposures and depended on the medium used.
authors.affiliation: Department of Medicine, University of Tübingen, Federal Republic of Germany.
authors.forename: K K
authors.initials: KK
authors.lastname: Haase
authors.forename: A
authors.initials: A
authors.lastname: Baumbach
authors.forename: M
authors.initials: M
authors.lastname: Wehrmann
authors.forename: S
authors.initials: S
authors.lastname: Duda
authors.forename: G
authors.initials: G
authors.lastname: Cerullo
authors.forename: B
authors.initials: B
authors.lastname: Rückle
authors.forename: E
authors.initials: E
authors.lastname: Steiger
authors.forename: K R
authors.initials: KR
authors.lastname: Karsch
mesh_terms: D016342:Angioplasty, Laser / Q000379:methods*; D001161:Arteriosclerosis / Q000473:pathology / Q000601:surgery*; D005069:Evaluation Studies as Topic; D006695:Holmium; D006801:Humans
chemical_list: D006695:Holmium