Maxwell AD. et al., 2023: Development of a burst wave lithotripsy system for noninvasive fragmentation of ureteroliths in pet cats.
Maxwell AD, Kim GW, Furrow E, Lulich JP, Torre M, MacConaghy B, Lynch E, Leotta DF, Wang YN, Borofsky MS, Bailey MR.
Department of Urology, University of Washington School of Medicine, Seattle, WA, USA.
Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, WA, USA.
Department of Veterinary Clinical Sciences, University of Minnesota, St. Paul, MN, USA.
Department of Urology, University of Minnesota, Minneapolis, MN, USA.
Department of Urology, University of Washington School of Medicine, Seattle, WA, USA.
Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, WA, USA.
Abstract
Background: Upper urinary tract stones are increasingly prevalent in pet cats and are difficult to manage. Surgical procedures to address obstructing ureteroliths have short- and long-term complications, and medical therapies (e.g., fluid diuresis and smooth muscle relaxants) are infrequently effective. Burst wave lithotripsy is a non-invasive, ultrasound-guided, handheld focused ultrasound technology to disintegrate urinary stones, which is now undergoing human clinical trials in awake unanesthetized subjects.
Results: In this study, we designed and performed in vitro testing of a modified burst wave lithotripsy system to noninvasively fragment stones in cats. The design accounted for differences in anatomic scale, acoustic window, skin-to-stone depth, and stone size. Prototypes were fabricated and tested in a benchtop model using 35 natural calcium oxalate monohydrate stones from cats. In an initial experiment, burst wave lithotripsy was performed using peak ultrasound pressures of 7.3 (n = 10), 8.0 (n = 5), or 8.9 MPa (n = 10) for up to 30 min. Fourteen of 25 stones fragmented to < 1 mm within the 30 min. In a second experiment, burst wave lithotripsy was performed using a second transducer and peak ultrasound pressure of 8.0 MPa (n = 10) for up to 50 min. In the second experiment, 9 of 10 stones fragmented to < 1 mm within the 50 min. Across both experiments, an average of 73-97% of stone mass could be reduced to fragments < 1 mm. A third experiment found negligible injury with in vivo exposure of kidneys and ureters in a porcine animal model.
Conclusions: These data support further evaluation of burst wave lithotripsy as a noninvasive intervention for obstructing ureteroliths in cats.
BMC Vet Res. 2023 Sep 2;19(1):141. doi: 10.1186/s12917-023-03705-1. PMID: 37660015 FREE PMC ARTICLE
Comments 1
A method, based on burst wave lithotripsy, is described for disintegration of ureteral stones in cats.
One interesting finding in this report was that stones measuring 3mm (2-5mm) and composed of COM and treated with an energy of 8MPa for 10 minutes resulted in fragments