Study on Feasibility of a New 805nm Semiconductor Laser as a Source in Laser Angioplasty

The authors studied on the feasibility of 805nm Laser produced by a new compact semiconductor laser equipment (Diomed 25, made in UK) to apply to laser angioplasty.The walls of fresh pig aorta and frozen human arteriosclerotic aorta were irradiated by this laser through bare-ended fibers at different power and exposure time, and the size of hole in terms of surface diameter and depth of holes created by vaporization was measured.The power of 25W was needed to vaporize and penetrate the aortic wall of both pig and human specimen.The pig aortic wall was penetrated by this laser irradiation for 1.2 to 18.4 seconds at 25W. The depth of vaporized hole ranged from 0.8 to 1.5mm. The volume of holes ranged from 0.224 to 1.26cmm. The human aortic wall was penetrated when irradiated through bulb type fiber for 2 to 5 seconds at 25W. The average diameter of a hole was 1.24mm, and the average depth was 2.3mm. The human aortic wall was vaporized when irradiated through a conical type fiber for 1 to 3 seconds at 25W, and the average diameter of a hole was 1.12 mm, and its depth was 1.85 mm in average.Once vaporization of aortic wall occurs, the time necessary to vaporize the wall became shorter for the second time. It is assumed that minute carbon particles sticked or adhered to the surface of the tip of a laser fiber from the first lasing produced more heat to the aortic wall, and thus the necessary time for vaporization was shortened.It seems to be important to keep this phenomenon in mind to apply laser to stenotic arterial wall in order to control optimal laser energy.It seems to be warranted to test the effect of a ceramic tip for contact irradiation of this new type of semiconductor laser before applying to clinical case.