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Rassweiler-Seyfried MC. et al., 2023: High-frequency shock wave lithotripsy: stone comminution and evaluation of renal parenchyma injury in a porcine ex-vivo model

Rassweiler-Seyfried MC, Mayer J, Goldenstedt C, Storz R, Marlinghaus E, Heine G, Alken P, Rassweiler JJ.
Department of Urology and Urosurgery, Medical Faculty Mannheim, University Medical Center Mannheim, University of Heidelberg.
Storz-Medical AG, Tägerwilen, Switzerland.
Department of Urology and Urosurgery, Medical Faculty Mannheim, University Medical Center Mannheim, University of Heidelberg.
Department for Urology and Andrology, Danube Private University, Krems, Austria.

Abstract

Background: The electrohydraulic high-frequency shock wave (Storz Medical, Taegerwilen, Switzerland) is a new way to create small fragments with frequencies up to 100 Hertz (Hz). This study evaluated the efficacy and safety of this method in a stone and porcine model.

Materials and methods: BEGO stones were put in a condom in a specifically designed fixture treated with different modulations to see stone comminution. Standardized ex vivo porcine model with perfused kidneys with 26 upper and lower poles of 15 kidneys was treated with the following modulations: voltage 16-24 kV, capacitor 12 nF and frequency up to 100 Hz. 2000-20,000 shock waves were applied to each pole. The kidneys were perfused with barium sulfate solution (BaSO4) and x-ray was performed to quantify the lesions using pixel volumetry.

Results: There was no correlation between the number of shock waves and the powdering degree or the applied Energy and the grade of pulverization in the stone model. Regarding the perfused kidney model, the number of shock waves, applied voltage and frequency had no direct correlation with the occurrence of parenchymal lesions The detected lesions of the renal parenchyma were minimal, technical parameters had no significant impact and the lesions did not differ from the results of former experiments using 1-1.5 Hz in the same model.

Conclusions: High-frequency shock wave lithotripsy can produce small stone fragments to pass in a very short time. The injury to the renal parenchyma is comparable to the results of the conventional SWL using 1-1.5 Hz.
World J Urol. 2023 Jun 7. doi: 10.1007/s00345-023-04441-9. Online ahead of print. PMID: 37284842
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Comments 1

Hans-Göran Tiselius on Tuesday, 15 August 2023 08:45

High frequency SWL is a new interesting technical development aiming at improved stone disintegration compared with what can be achieved with standard SWL. The hypothesis is that the rapid disintegration results in fragments smaller than 4 mm that will pass easier. The similarity with “stone dusting” is mentioned, but fragment passage is not only the result of size, but also of the intrarenal anatomy and patient mobility. This report is not a clinical study, and it remains to be shown that improved stone fragmentation also improves stone-free rates.

It is interesting to speculate about the development of SWL and compare what we can do today with modern lithotripters and what we were able to do with the original unmodified Dornier HM3 lithotripter. It is true that the trend away from SWL towards endoscopy is the result of technical development of endoscopy, but it is also a consequence of variably efficient lithotripters. The latter aspect at least partly has been concealed by continuously modified recommendations in guidelines. With the goal to carry out SWL without general or regional anesthesia, the indications for SWL have been narrowed.

In this perspective it is interesting to note that to achieve the results with high-frequency SWL it was necessary to abandon electromagnetic SW-generation and instead apply a technique based on electrohydraulic shock wave generation.
The results presented in this report are promising with good disintegration of the BEGO-stones without serious harm to the renal tissue. Remains to be shown: Does high-frequency SWL result in improved stone disintegration in a clinical setting and will such an outcome result in rapid stone/fragment-free calices?

Hans-Göran Tiselius

High frequency SWL is a new interesting technical development aiming at improved stone disintegration compared with what can be achieved with standard SWL. The hypothesis is that the rapid disintegration results in fragments smaller than 4 mm that will pass easier. The similarity with “stone dusting” is mentioned, but fragment passage is not only the result of size, but also of the intrarenal anatomy and patient mobility. This report is not a clinical study, and it remains to be shown that improved stone fragmentation also improves stone-free rates. It is interesting to speculate about the development of SWL and compare what we can do today with modern lithotripters and what we were able to do with the original unmodified Dornier HM3 lithotripter. It is true that the trend away from SWL towards endoscopy is the result of technical development of endoscopy, but it is also a consequence of variably efficient lithotripters. The latter aspect at least partly has been concealed by continuously modified recommendations in guidelines. With the goal to carry out SWL without general or regional anesthesia, the indications for SWL have been narrowed. In this perspective it is interesting to note that to achieve the results with high-frequency SWL it was necessary to abandon electromagnetic SW-generation and instead apply a technique based on electrohydraulic shock wave generation. The results presented in this report are promising with good disintegration of the BEGO-stones without serious harm to the renal tissue. Remains to be shown: Does high-frequency SWL result in improved stone disintegration in a clinical setting and will such an outcome result in rapid stone/fragment-free calices? Hans-Göran Tiselius
Saturday, 02 December 2023