Development of a burst wave lithotripsy system for noninvasive fragmentation of ureteroliths in pet cats

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