Enhanced Kidney Stone Fragmentation by Short Delay Tandem Conventional and Modified Lithotriptor Shock Waves: A Numerical Analysis

Abstract

Our numerical simulations suggest that for direct stress wave induced fragmentation modified shock waves should be as effective as conventional shock waves for fragmenting kidney stones. Also, with a small interval of 20 microseconds between the pulses tandem pulse lithotripsy using modified or conventional shock waves could be considerably more effective than single pulse lithotripsy for fragmenting kidney stones.

Combined short and long-delay tandem shock waves to improve shock wave lithotripsy according to the Gilmore–Akulichev theory

“…We designed a novel shock wave profile that enhances both stone damage due to shear and pitting. The first two shock waves of the novel profile hit the stone with a fixed time delay of 20 ls, increasing shear forces as reported by Tham et al [37]. The third pressure pulse, emitted hundreds of microseconds after the first, intensified bubble collapse.…”

“…In that case, stress and cavitation could not have been increased simultaneously and a two-stage SWL treatment as suggested by Tham and colleagues [37] would be needed.…”

“…Tham and colleagues [37] compared the stress field induced inside kidney stones by single-pulse shock waves with the stress produced by short-delay (Dt = 20 ls) tandem shock waves. The authors modeled the conventional lithotripter shock wave according to a simplified expression proposed by Church [38]:…”

Out-of-Focus Low Pressure Pulse Pretreatment to the Whole Kidney to Reduce Renal Injury During Shockwave Lithotripsy: AnIn VivoStudy Using a Rabbit Model

“…Several interesting approaches have been made to generate pressure profiles to better comminute urinary stones during SWL 3,4,9,10,[32][33][34][35][36][37][38][39] ; however, more strategies still need to be explored to reduce shockwave-induced tissue injury. There is a general consensus that better SWL outcomes result in patients treated at a low shockwave rate.…”

Recent finding and new technologies in nephrolithiasis: a review of the recent literature

“…Further reduction of frequency (30 sw/min) showed a protective effect on renal vessels in an animal model [71]. Furthermore, Tham et al observed optimal fragmentation by using a short delay time (20 μs) between shock waves [72]. …”