Erbium: YAG Laser Incision of Urethral Strictures for Treatment of Urinary Incontinence After Prostate Cancer Surgery

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Abstract : Urethral and bladder neck strictures occur in 5 to 20 percent of all prostate cancer surgery patients, resulting in urinary incontinence. Conventional treatments for stricture (including balloon dilation, cold knife incision, electrocautery, and Holmium laser incision) have widely variable success rates with suboptimal long-term results. The failure of these conventional stricture treatments is presumably due to mechanical and/or thermal damage to the urethral wall during the procedure. The purpose of this research project is to test a new laser, the Erbium:YAG laser, which is capable of precisely incising the urethral stricture with minimal peripheral damage to adjacent healthy tissue. The author hypothesizes that the minimal side effects caused during Erbium laser incision should translate into limited scarring and improved procedural success rates. The first year of this project was devoted to optimization of the laser and optical fiber delivery system for rapid and precise cutting of urethral tissue. Task 1 of the Statement of Work for Year 1 was the Modification of the Erbium:YAG laser system (Months 1-6). This task entailed two subtasks: (a) Modify electronics in laser power supply to produce shorter laser pulses, more uniform temporal beam profile, and higher pulse repetition rates; and (b) Optimize laser ablation parameters (laser energy, pulse duration, repetition rate, and irradiation time) using in vitro tissue samples. Task 2 for Year 1 was to determine the optimal optical fiber delivery system (Months 7-12). This task entailed three subtasks: (a) Test fiber optic damage thresholds with chemical and microscopic analysis of fiber tips after laser ablation with fiber in contact with tissue, (b) Design side-firing laser fibers with varying delivery angles for incision of urethral wall, and (c) Build hybrid fibers combining flexible germanium oxide trunk fiber with durable sapphire probe tip to prevent fiber damage. (4 tables, 7 figures, 13 refs.)