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: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

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 (US)
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
EditorsK.E. Bartels, L.S. Bass, W.T.W. Riese, K.W. Gregory, H. Hirschberg, A. Katzir, N. Kollias, S.J. Madsen, R.S. Malek
Pages105-111
Number of pages7
Volume5
Edition1
DOIs
StatePublished - 2004
EventLasers in Surgery: Advanced Characterization, Therapeutics, and Systems XIV - San Jose, CA, United States
Duration: Jan 24 2004Jan 27 2004

Other

OtherLasers in Surgery: Advanced Characterization, Therapeutics, and Systems XIV
CountryUnited States
CitySan Jose, CA
Period1/24/041/27/04

Keywords

  • Erbium
  • Laser
  • Stricture
  • Ureter
  • Urethra

ASJC Scopus subject areas

  • Engineering(all)

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