Holmium: YAG lithotripsy: Photothermal mechanism

George J. Vassar, Kin F. Chan, Joel M H Teichman, Randolph D. Glickman, Susan T. Weintraub, T. Joshua Pfefer, Ashley J. Welch

Research output: Contribution to journalArticle

147 Citations (Scopus)

Abstract

Objective: A series of experiments were conducted to test the hypothesis that the mechanism of holmium:YAG lithotripsy is photothermal. Methods and Results: To show that holmium:YAG lithotripsy requires direct absorption of optical energy, stone loss was compared for 150 J Ho:YAG lithotripsy of calcium oxalate monohydrate (COM) stones for hydrated stones irradiated in water (17 ± 3 mg) and hydrated stones irradiated in air (25 ± 9 mg) v dehydrated stones irradiated in air (40 ± 12 mg) (P < 0.001). To show that Ho:YAG lithotripsy occurs prior to vapor bubble collapse, the dynamics of lithotripsy in water and vapor bubble formation were documented with video flash photography. Holmium:YAG lithotripsy began at 60 μsec, prior to vapor bubble collapse. To show that Ho:YAG lithotripsy is fundamentally related to stone temperature, cystine, and COM mass loss was compared for stones initially at room temperature (~ 23°C) v frozen stones ablated within 2 minutes after removal from the freezer. Cystine and COM mass losses were greater for stones starting at room temperature than cold (P ≤ 0.05). To show that Ho:YAG lithotripsy involves a thermochemical reaction, composition analysis was done before and after lithotripsy. Postlithotripsy, COM yielded calcium carbonate; cystine yielded cysteine and free sulfur; calcium hydrogen phosphate dihydrate yielded calcium pyrophosphate; magnesium ammonium phosphate yielded ammonium carbonate and magnesium carbonate; and uric acid yielded cyanide. To show that Ho:YAG lithotripsy does not create significant shockwaves, pressure transients were measured during lithotripsy using needle hydrophones. Peak pressures were < 2 bars. Conclusion: The primary mechanism of Ho:YAG lithotripsy is photothermal. There are no significant photoacoustic effects.

Original languageEnglish (US)
Pages (from-to)181-190
Number of pages10
JournalJournal of Endourology
Volume13
Issue number3
StatePublished - Apr 1999

Fingerprint

Holmium
Lithotripsy
Calcium Oxalate
Cystine
Air
Calcium Pyrophosphate
Pressure
Temperature
Calcium Carbonate
Photography
Steam
Cyanides
Uric Acid
Sulfur

ASJC Scopus subject areas

  • Urology

Cite this

Vassar, G. J., Chan, K. F., Teichman, J. M. H., Glickman, R. D., Weintraub, S. T., Pfefer, T. J., & Welch, A. J. (1999). Holmium: YAG lithotripsy: Photothermal mechanism. Journal of Endourology, 13(3), 181-190.

Holmium : YAG lithotripsy: Photothermal mechanism. / Vassar, George J.; Chan, Kin F.; Teichman, Joel M H; Glickman, Randolph D.; Weintraub, Susan T.; Pfefer, T. Joshua; Welch, Ashley J.

In: Journal of Endourology, Vol. 13, No. 3, 04.1999, p. 181-190.

Research output: Contribution to journalArticle

Vassar, GJ, Chan, KF, Teichman, JMH, Glickman, RD, Weintraub, ST, Pfefer, TJ & Welch, AJ 1999, 'Holmium: YAG lithotripsy: Photothermal mechanism', Journal of Endourology, vol. 13, no. 3, pp. 181-190.
Vassar GJ, Chan KF, Teichman JMH, Glickman RD, Weintraub ST, Pfefer TJ et al. Holmium: YAG lithotripsy: Photothermal mechanism. Journal of Endourology. 1999 Apr;13(3):181-190.
Vassar, George J. ; Chan, Kin F. ; Teichman, Joel M H ; Glickman, Randolph D. ; Weintraub, Susan T. ; Pfefer, T. Joshua ; Welch, Ashley J. / Holmium : YAG lithotripsy: Photothermal mechanism. In: Journal of Endourology. 1999 ; Vol. 13, No. 3. pp. 181-190.
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