2079 ENERGY AND PULSE REPETITION FREQUENCY DEPENDENT TISSUE INJURY PRODUCED BY A MODIFIED ACOUSTIC LENS FOR ELECTROMAGNETIC LITHOTRIPTERS

Abstract

You have accessJournal of UrologyStone Disease: Basic Research (I)1 Apr 20132079 ENERGY AND PULSE REPETITION FREQUENCY DEPENDENT TISSUE INJURY PRODUCED BY A MODIFIED ACOUSTIC LENS FOR ELECTROMAGNETIC LITHOTRIPTERS Andreas Neisius, Nathan Smith, Nicholas J. Kuntz, Tim Schykowski, Gaston M. Astroza, Ramy Youssef, Muhammad W. Iqbal, Michael E. Lipkin, Michael N. Ferrandino, Michael R. Gustafson, Walther N. Simmons, Glenn M. Preminger, and Pei Zhong Andreas NeisiusAndreas Neisius Durham, NC More articles by this author , Nathan SmithNathan Smith Durham, NC More articles by this author , Nicholas J. KuntzNicholas J. Kuntz Durham, NC More articles by this author , Tim SchykowskiTim Schykowski Durham, NC More articles by this author , Gaston M. AstrozaGaston M. Astroza Durham, NC More articles by this author , Ramy YoussefRamy Youssef Durham, NC More articles by this author , Muhammad W. IqbalMuhammad W. Iqbal Durham, NC More articles by this author , Michael E. LipkinMichael E. Lipkin Durham, NC More articles by this author , Michael N. FerrandinoMichael N. Ferrandino Durham, NC More articles by this author , Michael R. GustafsonMichael R. Gustafson Durham, NC More articles by this author , Walther N. SimmonsWalther N. Simmons Durham, NC More articles by this author , Glenn M. PremingerGlenn M. Preminger Durham, NC More articles by this author , and Pei ZhongPei Zhong Durham, NC More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.2498AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The acoustic lens of a Siemens Modularis electromagnetic shock wave lithotripter has been further modified to reduce pre-focal cavitation while generating a pressure waveform and broad focal zone mimicking the Dornier HM3 electrohydraulic device. We sought to determine the threshold for the maximum acoustic energy which can be safely applied to a kidney under clinically relevant treatment protocols, and the dependency of tissue injury on pulse repetition frequency (PRF). METHODS Tissue injury (TI) produced by the original and modified lenses in a swine model were first evaluated starting from the highest output level to determine the threshold energy for safe lithotripsy. Thereafter, TI was assessed under an effective acoustic pulse energy for the leading compressive wave (E+)of 44 mJ. A clinical protocol with a soft ramping scheme was used to deliver 3000 shock waves to each kidney using a PRF of 1.0 and 1.5 Hz, leading to a total accumulated energy of 112.84 J. Following lithotripsy, kidneys were perfused, harvested, dehydrated, cast in paraffin wax, and sectioned. Photographic images were taken every 120 μm and analyzed to determine the functional renal volume (FRV) damage. RESULTS Gross subcapsular hematomas were produced by both the original and modified lenses at E+ of 51 mJ. Using E+ of 44 mJ, the modified lens showed quantatively macroscopic tissue injury (subcapsular hematoma) in 1/6 renal units (17%) in the 1.5 Hz group. No macroscopic tissue injury was detected in the 1.0 Hz group (0/6 renal units). After processing of the digitalized images TI was detected in 0.432 % (±0.51%) of the FRV (with a maximum level of 1.324% in the kidney with the gross hematoma) in the 1.5 Hz group and in 0.009% (±0.015%) of the FRV in the 1 Hz group (p=0.025), respectively. CONCLUSIONS This study demonstrates that the energy threshold for gross TI of the modified lens is comparable to the original lens. Our data further confirms that the initiation of TI depends on acoustic pulse energy, and the extent of TI depends on the total accumulated acoustic energy delivered to a kidney, as well as on PRF. Overall, our results suggest that a rational design of treatment strategies to minimize tissue injury in SWL is warranted. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e853 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Andreas Neisius Durham, NC More articles by this author Nathan Smith Durham, NC More articles by this author Nicholas J. Kuntz Durham, NC More articles by this author Tim Schykowski Durham, NC More articles by this author Gaston M. Astroza Durham, NC More articles by this author Ramy Youssef Durham, NC More articles by this author Muhammad W. Iqbal Durham, NC More articles by this author Michael E. Lipkin Durham, NC More articles by this author Michael N. Ferrandino Durham, NC More articles by this author Michael R. Gustafson Durham, NC More articles by this author Walther N. Simmons Durham, NC More articles by this author Glenn M. Preminger Durham, NC More articles by this author Pei Zhong Durham, NC More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...