Document Detail

Holmium: YAG lithotripsy: photothermal mechanism.
MedLine Citation:
PMID:  10360498     Owner:  NLM     Status:  MEDLINE    
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 microsec, 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 (approximately 23 degrees 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 < or = 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.
G J Vassar; K F Chan; J M Teichman; R D Glickman; S T Weintraub; T J Pfefer; A J Welch
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of endourology / Endourological Society     Volume:  13     ISSN:  0892-7790     ISO Abbreviation:  J. Endourol.     Publication Date:  1999 Apr 
Date Detail:
Created Date:  1999-08-11     Completed Date:  1999-08-11     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8807503     Medline TA:  J Endourol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  181-90     Citation Subset:  IM    
Division of Urology, The University of Texas Health Science Center, San Antonio, USA.
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MeSH Terms
Analysis of Variance
Calculi / therapy*
Hot Temperature*
Lithotripsy, Laser / methods*
Video Recording
Reg. No./Substance:
7440-60-0/Holmium; 7440-65-5/Yttrium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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