Burst Wave Lithotripsy for the Treatment of Ureteral Calculi

DESCRIPTIONprovided by applicantSignificanceUrinary tract stones pose a significant healthcare burdenwith costs to the US exceeding $billion annuallyThe impact of stone disease on the healthcare system is expected to continue to grow as risk factors such as diabetes and obesity become more prevalentUreteral stones in particular pose a management challenge as they are often symptomaticand spontaneous passage is a strong function of stone size and locationWatchful waiting in combination with expulsion therapy is the first line approachbut can lead to repeat physician and or emergency department visitslost productivityand stress on the patientFor active interventionextracorporeal shock wave lithotripsySWLoften requires repeat or secondary procedures to achieve stone free statusUreteroscopya minimally invasive procedurehas greater stone free rates than SWLbut higher complication ratesTechnologyBurst wave lithotripsyBWLis a novelnoninvasivemethod of stone fragmentation that has the potential to significantly improve the management of ureteral stonesBWL uses multi cyclelow amplitude pulses of ultrasound rather than shock waves to noninvasively induce stone fractureThis approach has the potential to reduce the risk of injuryprocedural complicationsand additional proceduresas well as result in a significant reduction in procedural time and costFurthermorethe low pulse pressure amplitude used may preclude the need for anesthesiaproviding an attractive alternative to watchful waitingPreliminary DataIn vitro studies have shown the technology is capable of breaking all common types of stones found in humansResults also show that the fragment size can be controlled by altering the ultrasound frequency to produce small fragments likely to spontaneously pass without further symptomsPreliminary studies indicate the pressure levels required to break stones are significantly below the pressure levels required to induce renal injury in a porcine animal studySpecific AimsThis is a fast track proposal that will use Phase I to address the technical question of how BWL parameters should be altered to treat a stone obstructed within a ureter compared to a stone free in a water bathThis will require assembly of a BWL transducer and amplifierPhase I Aimand in vitro studies to establish the pressure level and dosetimerequired to break stones within a ureteral phantomPhase I AimPhase II identifies the acoustic windows and critical structures exposed while targeting ureteral stonesPhase II Aimand designs the commercial prototype transducer specific for those windows and operating the acoustic parameters identified in Phase IPhase II AimThe BWL system will be guided by an ultrasound imaging system with specialized algorithms to enhance targeting and detect cavitation to monitor and control for injuryPhase II AimThe safety and efficacy of the developed system will be tested in a porcine animal modelPhase II Aims