Myocardial Revasc Diffrac Limited Fiber-Tip Laser

Myocardial infarction is the major pathological killer in America, resulting in the deaths of morethan 500,000 persons each year. Despite important advances which have been made in preventing andtreating atherosclerotic cardiovascular disease, coronary artery impairments continue to constitute amajor health problem. Significant numbers of afflicted individuals who are not candidates for eitherbypass surgery or angioplasty as therapeutic procedures for the treatment of myocardial ischemia willbenefit from a technique for accomplishing direct revascularization. A non-divergent laser beam locatedat the distal tip of a subcutaneous catheter would provide an operator with the critical control neededto create precise cylindrical channels in the wall of the left ventricle, without opening the chest cavity.We will accomplish this task by using arrays of AlGaAs lasers, configured as one centimeter bars, topump a miniature Er:YLF laser, emitting at the 2800 nm water absorption band. A catheter housing willbe designed that places the miniature Er:YLF laser, on the order of one centimeter long, at the tip of thecatheter; pumping energy will be conveyed to the tip via a glass optical fiber. We presently producesdiode laser arrays featuring power levels of 2500 W/cm, sufficient for performing tissue ablation. Anoptical integrator will couple the optical energy from the diode laser bar into the circular fiber. Theproposed effort will establish conditions, including spectral watching and input/output coupling formaximum energy transfer for effectively coupling the output flux from an array of laser diodes into thefundamental mode volume of the solid-state laser. Preliminary effects on porcine myocardial tissuesamples will be evaluated.