Optimization of treatment strategy used during shockwave lithotripsy to maximize stone fragmentation efficiency.

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Yong, Daniel Z
Lipkin, Michael E
Simmons, W Neal
Sankin, Georgy
Albala, David M
Zhong, Pei
Preminger, Glenn M

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BACKGROUND AND PURPOSE: Previous studies have demonstrated that treatment strategy plays a critical role in ensuring maximum stone fragmentation during shockwave lithotripsy (SWL). We aimed to develop an optimal treatment strategy in SWL to produce maximum stone fragmentation. MATERIALS AND METHODS: Four treatment strategies were evaluated using an in-vitro experimental setup that mimics stone fragmentation in the renal pelvis. Spherical stone phantoms were exposed to 2100 shocks using the Siemens Modularis (electromagnetic) lithotripter. The treatment strategies included increasing output voltage with 100 shocks at 12.3 kV, 400 shocks at 14.8 kV, and 1600 shocks at 15.8 kV, and decreasing output voltage with 1600 shocks at 15.8 kV, 400 shocks at 14.8 kV, and 100 shocks at 12.3 kV. Both increasing and decreasing voltages models were run at a pulse repetition frequency (PRF) of 1 and 2 Hz. Fragmentation efficiency was determined using a sequential sieving method to isolate fragments less than 2 mm. A fiberoptic probe hydrophone was used to characterize the pressure waveforms at different output voltage and frequency settings. In addition, a high-speed camera was used to assess cavitation activity in the lithotripter field that was produced by different treatment strategies. RESULTS: The increasing output voltage strategy at 1 Hz PRF produced the best stone fragmentation efficiency. This result was significantly better than the decreasing voltage strategy at 1 Hz PFR (85.8% vs 80.8%, P=0.017) and over the same strategy at 2 Hz PRF (85.8% vs 79.59%, P=0.0078). CONCLUSIONS: A pretreatment dose of 100 low-voltage output shockwaves (SWs) at 60 SWs/min before increasing to a higher voltage output produces the best overall stone fragmentation in vitro. These findings could lead to increased fragmentation efficiency in vivo and higher success rates clinically.





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Yong, Daniel Z, Michael E Lipkin, W Neal Simmons, Georgy Sankin, David M Albala, Pei Zhong and Glenn M Preminger (2011). Optimization of treatment strategy used during shockwave lithotripsy to maximize stone fragmentation efficiency. J Endourol, 25(9). pp. 1507–1511. 10.1089/end.2010.0732 Retrieved from https://hdl.handle.net/10161/5090.

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Michael Eric Lipkin

Cary N. Robertson, MD, Associate Professor

Walter Neal Simmons

Gendell Family Professor of the Practice

Pei Zhong

Professor in the Thomas Lord Department of Mechanical Engineering and Materials Science

My research focuses on engineering and technology development with applications in the non-invasive or minimally invasive treatment of kidney stone disease via shock wave and laser lithotripsy, high-intensity focused ultrasound (HIFU) and immunotherapy for cancer treatment, acoustic and optical cavitation, and ultrasound neuromodulation via sonogenetics. 

We are taking an integrated and translational approach that combines fundamental research with engineering and applied technology development to devise novel and enabling ultrasonic, optical, and mechanical tools for a variety of clinical applications. We are interested in shock wave/laser-fluid-bubble-solid interaction, and resultant mechanical and thermal fields that lead to material damage and removal.  We also investigate the stress response of biological cell and tissue induced by cavitation and ultrasound exposure, mediated through mechanosensitive ion channels, such as Piezo 1. Our research activities are primarily supported by NIH and through collaborations with the medical device industry.


Glenn Michael Preminger

James F. Glenn, M.D. Distinguished Professor of Urology
  1. Minimally invasive management of urologic diseases
    2. Minimally invasive management of renal and ureteral stones
    3. Medical management of nephrolithiasis
    4. Bioeffects of shock wave lithotripsy
    5. Basic physics of shock wave lithotripsy
    6. Intracorporeal lithotripsy for stone fragmentation
    7. Minimally invasive management of urinary tract obstruction, including ureteropelvic junction obstruction and ureteral strictures
    8. Enhanced imaging modalities for minimally invasive surgery
    9. Digital video imaging during endoscopic surgery
    10. 3-D imaging modalities for minimally invasive surgery
    11. Holmium laser applications in urology

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