Effect of initial shock wave voltage on shock wave lithotripsy-induced lesion size during step-wise voltage ramping

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From: BJU International(Vol. 103, Issue 1)
Publisher: Wiley Subscription Services, Inc.
Document Type: Report
Length: 409 words

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To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1464-410X.2008.07922.x Byline: Bret A. Connors, Andrew P. Evan, Philip M. Blomgren, Rajash K. Handa, Lynn R. Willis (*), Sujuan Gao ([dagger]) Keywords: tissue injury; animal models; renal protection Abstract: OBJECTIVE To determine if the starting voltage in a step-wise ramping protocol for extracorporeal shock wave lithotripsy (SWL) alters the size of the renal lesion caused by the SWs. MATERIALS AND METHODS To address this question, one kidney from 19 juvenile pigs (aged 7-8 weeks) was treated in an unmodified Dornier HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA) with either 2000 SWs at 24 kV (standard clinical treatment, 120 SWs/min), 100 SWs at 18 kV followed by 2000 SWs at 24 kV or 100 SWs at 24 kV followed by 2000 SWs at 24 kV. The latter protocols included a 3-4 min interval, between the 100 SWs and the 2000 SWs, used to check the targeting of the focal zone. The kidneys were removed at the end of the experiment so that lesion size could be determined by sectioning the entire kidney and quantifying the amount of haemorrhage in each slice. The average parenchymal lesion for each pig was then determined and a group mean was calculated. RESULTS Kidneys that received the standard clinical treatment had a mean (sem) lesion size of 3.93 (1.29)% functional renal volume (FRV). The mean lesion size for the 18 kV ramping group was 0.09 (0.01)% FRV, while lesion size for the 24 kV ramping group was 0.51 (0.14)% FRV. The lesion size for both of these groups was significantly smaller than the lesion size in the standard clinical treatment group. CONCLUSIONS The data suggest that initial voltage in a voltage-ramping protocol does not correlate with renal damage. While voltage ramping does reduce injury when compared with SWL with no voltage ramping, starting at low or high voltage produces lesions of the same approximate size. Our findings also suggest that the interval between the initial shocks and the clinical dose of SWs, in our one-step ramping protocol, is important for protecting the kidney against injury. Author Affiliation: (*)Pharmacology and Toxicology, ([dagger])Medicine, Division of Biostatistics, Indiana University School of Medicine, Indianapolis, IN, USA Article History: Accepted for publication 30 May 2008 Article note: Bret A. Connors, Indiana University School of Medicine, Department of Anatomy and Cell Biology, Medical Science Building, Room 5055, 635 Barnhill Drive, Indianapolis, IN 46202, USA. e-mail: connors@anatomy.iupui.edu

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Gale Document Number: GALE|A190437855