HOLMIUM-YTTRIUM-ALUMINUM-GARNET LITHOTRIPSY EFFICIENCY VARIES WITH STONE COMPOSITION

Objectives. To test the hypothesis that holmium:yttrium-aluminum-garne t (YAG) lithotripsy efficiency varies with stone composition. Methods. Single pulses of holmium:YAG energy were delivered using 272-, 365-, 550-, and 940-mu m optical fibers to human calculi composed of calcium oxalate monohydrate (COM), calcium hydrogen phosphate dihydrate (CHPD ), cystine, magnesium ammonium phosphate hexohydrate (MAPH), and uric acid. Energy/pulse settings were 0.2, 0.5, 1.0, and 1.5 J. Stone crate r width and depth were characterized with reflectance light microscopy . Results. For similar energies overall MAPH yielded the deepest and w idest craters. CHPD, cystine, and uric acid yielded craters of interme diate width and depth. COM yielded the smallest craters. Within any gi ven composition, increased pulse energy yielded craters of increased w idth and depth. Conclusions. Holmium:YAG lithotripsy efficiency varies with stone composition. The rank order of crater size appears to corr elate with thermal threshold for each composition. Increased holmium:Y AG energy produces larger craters for all compositions. UROLOGY 52: 39 2-397, 1998. (C) 1998, Elsevier Science Inc. All rights reserved.