Variable pulsewidth Erbium:YAG laser ablation of the ureter and urethra in vitro and in vivo: Optimization of the laser fluence, pulse duration, and pulse repetition rate

Nathaniel M. Fried, Zelalem Tesfaye, Albert M. Ong, Koon H. Rha, Pooya Hejazi

Research output: Contribution to journalConference article


Stricture recurrence frequently occurs due to mechanical or thermal insult during endourologic treatment of ureteral and urethral strictures. Optimization of the Er:YAG laser for precise incision of strictures was conducted using ureteral and urethral tissue samples, ex vivo, and a laparoscopic porcine ureteral model with exposed ureter, in vivo. Erbium:YAG laser radiation with a wavelength of 2.94 microns, pulse lengths of 8, 70, and 220 microseconds, output energies of 2-35 mJ, fluences of 1-25 J/cm 2, and pulse repetition rates of 5-30 Hz, was delivered through germanium oxide optical fibers in contact with the tissue. Incision of the ureteral wall was achieved in vivo with less than 20 pulses at a laser fluence of 4 J/cm 2. Thermal damage was reduced from 30-60 microns to 10-20 microns by shortening the laser pulse duration from 220 to 70 microseconds. Pulse repetition rates above 20 Hz resulted in larger thermal damage zones ranging from 60-120 microns. The Er:YAG laser, operating at a pulse duration of approximately 70 microseconds, a fluence of 4 J/cm 2 or greater, and a repetition rate less than 20 Hz, is capable of rapidly incising urethral and ureteral tissues, in vivo, with minimal thermal and mechanical side-effects.

Original languageEnglish
Article number25
Pages (from-to)105-111
Number of pages7
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Issue number1
Publication statusPublished - 2004 Dec 1
EventLasers in Surgery: Advanced Characterization, Therapeutics, and Systems XIV - San Jose, CA, United States
Duration: 2004 Jan 242004 Jan 27


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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