Innovaciones tecnológicas en la litotricia de ondas de choque / Technological innovations in shock wave lithotripsy

Introducción Desde 1980, la litotricia extracorpórea por ondas de choque (SWL) ha sido empleada en el tratamiento de las litiasis urinarias, ofreciendo alternativas no invasivas a las técnicas quirúrgicas. Aunque limitada por tamaño y ubicación de las piedras, su efectividad se ve afectada por varios factores. A pesar de la evolución de técnicas quirúrgicas, la SWL podría mantener su relevancia con nuevos avances. Nuestro objetivo es revisar la bibliografía existente para recopilar los mayores avances hasta la fecha en el tratamiento extracorpóreo de la litiasis. Material y métodos Se ha realizado una revisión bibliográfica no sistemática, entre los años 2017 a 2023 para obtener 26 artículos sobre 3 tipos de innovación tecnológica en litotricia extracorpórea: Burst Wave Lithotripsy (BWL), Histotripsy y Microbubble Lithotripsy (ML). Resultados La BWL emplea ondas sinusoidales ultrasónicas de menor y mayor frecuencia que la SWL tradicional. Su mecanismo de acción genera una fragmentación de mayor calidad (finos fragmentos) en lugar de generar fuerzas tensionales como en la SWL tradicional que generan líneas de fractura que dan lugar a fragmentos de mayor tamaño. Resultados en cerdos y humanos han mostrado fragmentación efectiva con buen perfil de seguridad. Basada en la tecnología de ultrasonido focalizado de alta intensidad (HIFU), la histotricia fragmenta tejido empleando fenómenos de cavitación. Han mostrado buenos resultados in vitro, aunque la formación de microburbujas que se interponen entre la litiasis y las ondas de ultrasonido son un impedimento para el progreso de esta técnica. La ML combina microburbujas y ultrasonido para fragmentar litiasis con seguridad y eficacia. Resultados in vitro y en cerdos son prometedores. Puede optimizar tratamientos y reducir niveles energéticos. Conclusiones La innovación tecnológica no solo se está aplicando a técnicas endourológicas, sino también a la ESWL. ... (AU)

Introduction Since 1980, extracorporeal Shock Wave Lithotripsy (SWL) has been employed in the treatment of urolithiasis, offering noninvasive alternatives to surgical techniques. In addition to being limited by the size and location of the stones, its efficacy is influenced by several factors. Despite the advancement of other surgical techniques, SWL could maintain its position with new improvements. Our objective is to review the existing literature on the latest advances in the extracorporeal treatment of lithiasis. Material and methods A non-systematic literature review was carried out from 2017 to 2023 to obtain 26 articles on three different emerging technologies in extracorporeal lithotripsy: Burst Wave Lithotripsy (BWL), Histotripsy, and Microbubble Lithotripsy (ML). Results The BWL uses sinusoidal bursts of US waves delivered at lower and higher frequencies than conventional SWL. Its mechanism of action generates a higher quality fragmentation (fine fragments) instead of generating tensile stresses for stone fracture resulting in larger fragments, as in traditional SWL. Studies in pigs and humans have shown effective fragmentation with a good safety profile. Based on High Intensity Focused Ultrasound (HIFU) technology, histotripsy fragments tissue through cavitation. Good in vitro results have been shown, but the formation of microbubbles between the stone and ultrasound waves hinders the progress of this technique. Microbubble Lithotripsy (ML) combines microbubbles and ultrasound for safe and effective stone fragmentation. In vitro and pig results are promising. This technique can help optimize treatments and reduce energy levels. Conclusions Technological innovation is not only being applied to endourological techniques, but also to ESWL. New techniques such as BWL, histotripsy and ML are promising, with good results in the research phase. (AU)

Technological innovations in shock wave lithotripsy.

INTRODUCTION: Since 1980, extracorporeal shock wave lithotripsy (SWL) has been employed in the treatment of urolithiasis, offering noninvasive alternatives to surgical techniques. In addition to being limited by the size and location of the stones, its efficacy is influenced by several factors. Despite the advancement of other surgical techniques, SWL could maintain its position with new improvements. Our objective is to review the existing literature on the latest advances in the extracorporeal treatment of lithiasis. MATERIAL AND METHODS: A non-systematic literature review was carried out from 2017 to 2023 to obtain 26 articles on three different emerging technologies in extracorporeal lithotripsy: Burst Wave Lithotripsy (BWL), Histotripsy, and Microbubble Lithotripsy (ML). RESULTS: The BWL uses sinusoidal bursts of US waves delivered at lower and higher frequencies than conventional SWL. Its mechanism of action generates a higher quality fragmentation (fine fragments) instead of generating tensile stresses for stone fracture resulting in larger fragments, as in traditional SWL. Studies in pigs and humans have shown effective fragmentation with a good safety profile. Based on High Intensity Focused Ultrasound (HIFU) technology, histotripsy fragments tissue through cavitation. Good in vitro results have been shown, but the formation of microbubbles between the stone and ultrasound waves hinders the progress of this technique. Microbubble Lithotripsy (ML) combines microbubbles and ultrasound for safe and effective stone fragmentation. In vitro and pig results are promising. This technique can help optimize treatments and reduce energy levels. CONCLUSIONS: Technological innovation is not only being applied to endourological techniques, but also to ESWL. New techniques such as BWL, histotripsy and ML are promising, with good results in the research phase.

Factors Affecting Tissue Cavitation during Burst Wave Lithotripsy.

Burst wave lithotripsy (BWL) is a technology under clinical investigation for non-invasive fragmentation of urinary stones. Under certain ranges of ultrasound exposure parameters, this technology can cause cavitation in tissue leading to renal injury. This study sought to measure the focal pressure amplitude needed to cause cavitation in vivo and determine its consistency in native tissue, in an implanted stone model and under different exposure parameters. The kidneys of eight pigs were exposed to transcutaneous BWL ultrasound pulses. In each kidney, two locations were targeted: the renal sinus and the kidney parenchyma. Each was exposed for 5 min at a set pressure level and parameters, and cavitation was detected using an active cavitation imaging method based on power Doppler ultrasound. The threshold was determined by incrementing the pressure amplitude up or down after each 5-min interval until cavitation occurred/subsided. The pressure thresholds were remeasured postsurgery, targeting an implanted stone or collecting space (in sham). The presence of a stone or sham surgery did not significantly impact the threshold for tissue cavitation. Targeting parenchyma instead of kidney collecting space and lowering the ultrasound pulse repetition frequency both resulted in an increased pressure threshold for cavitation.

First In-Human Burst Wave Lithotripsy for Kidney Stone Comminution: Initial Two Case Studies.

Purpose: To test the effectiveness (Participant A) and tolerability (Participant B) of urinary stone comminution in the first-in-human trial of a new technology, burst-wave lithotripsy (BWL). Materials and Methods: An investigational BWL and ultrasonic propulsion system was used to target a 7-mm kidney stone in the operating room before ureteroscopy (Participant A). The same system was used to target a 7.5 mm ureterovesical junction stone in clinic without anesthesia (Participant B). Results: For Participant A, a ureteroscope inserted after 9 minutes of BWL observed fragmentation of the stone to <2 mm fragments. Participant B tolerated the procedure without pain from BWL, required no anesthesia, and passed the stone on day 15. Conclusions: The first-in-human tests of BWL pulses were successful in that a renal stone was comminuted in <10 minutes, and BWL was also tolerated by an awake subject for a distal ureteral stone. Clinical Trial NCT03873259 and NCT02028559.

Emerging Technologies in Lithotripsy.

This comprehensive review updates the advances in extracorporeal lithotripsy, including improvements in external shockwave lithotripsy and innovations in ultrasound based lithotripsy, such as burst wave lithotripsy, ultrasonic propulsion, and histotripsy. Advances in endoscopic technology and training have changed the surgical approach to nephrolithiasis; however, improvements and innovations in extracorporeal lithotripsy maintain its status as an excellent option in appropriately selected patients.

Innovations in Ultrasound Technology in the Management of Kidney Stones.

This article reviews new advances in ultrasound technology for urinary stone disease. Recent research to facilitate the diagnosis of nephrolithiasis, including use of the twinkling signal and posterior acoustic shadow, have helped to improve the use of ultrasound examination for detecting and sizing renal stones. New therapeutic applications of ultrasound technology for stone disease have emerged, including ultrasonic propulsion to reposition stones and burst wave lithotripsy to fragment stones noninvasively. The safety, efficacy, and evolution of these technologies in phantom, animal, and human studies are reviewed herein. New developments in these rapidly growing areas of ultrasound research are also highlighted.

Evaluation of Renal Stone Comminution and Injury by Burst Wave Lithotripsy in a Pig Model.

Introduction: Burst wave lithotripsy is an experimental technology to noninvasively fragment kidney stones with focused bursts of ultrasound (US). This study evaluated the safety and effectiveness of specific lithotripsy parameters in a porcine model of nephrolithiasis. Methods: A 6- to 7-mm human kidney stone was surgically implanted in each kidney of three pigs. A burst wave lithotripsy US transducer with an inline US imager was coupled to the flank and the lithotripter focus was aligned with the stone. Each stone was exposed to burst wave lithotripsy at 6.5 to 7 MPa focal pressure for 30 minutes under real-time image guidance. After treatment, the kidneys were removed for gross, histologic, and MRI assessment. Stone fragments were retrieved from the kidney to determine the mass comminuted to pieces <2 mm. Results: On average, 87% of the stone mass was reduced to fragments <2 mm. In three of five treatments, stones were completely comminuted to <2-mm fragments. In two of five treatments, stones were partially disintegrated, but larger fragments remained. One stone was not treated because no suitable acoustic window was identified. No injury was detected through gross, histologic, or MRI examination in the parenchymal tissue, although petechial damage and surface erosion were identified on the urothelium of the collecting system limited to the area around the stone. Conclusion: Burst wave lithotripsy can consistently produce stone fragments small enough to spontaneously pass by transcutaneous administration of US pulses. The data suggest that such exposures produce minimal injury to the kidney and urinary tract.

Combined Burst Wave Lithotripsy and Ultrasonic Propulsion for Improved Urinary Stone Fragmentation.

PURPOSE: Burst wave lithotripsy (BWL) is a new technology in development to fragment urinary stones. Ultrasonic propulsion (UP) is a separate technology under investigation for displacing stones. We measure the effect of propulsion pulses on stone fragmentation from BWL. MATERIALS AND METHODS: Two artificial stone models (crystalline calcite, BegoStone plaster) and human calcium oxalate monohydrate (COM) stones measuring 5 to 8 mm were subjected to ultrasound exposures in a polyvinyl chloride tissue phantom within a water bath. Stones were exposed to BWL with and without propulsion pulses interleaved for set time intervals depending on stone type. Fragmentation was measured as a fraction of the initial stone mass fragmented to pieces smaller than 2 mm. RESULTS: BegoStone model comminution improved from 6% to 35% (p < 0.001) between BWL and BWL with interleaved propulsion in a 10-minute exposure. Propulsion alone did not fragment stones, whereas addition of propulsion after BWL slightly improved BegoStone model comminution from 6% to 11% (p < 0.001). BegoStone model fragmentation increased with rate of propulsion pulses. Calcite stone fragmentation improved from 24% to 39% in 5 minutes (p = 0.047) and COM stones improved from 17% to 36% (p = 0.01) with interleaved propulsion. CONCLUSIONS: BWL with UP improved stone fragmentation compared with BWL alone in vitro. The improvement was greatest when propulsion pulses are interleaved with BWL treatment and when propulsion pulses are applied at a higher rate. Thus, UP may be a useful adjunct to enhance fragmentation in lithotripsy in vivo.

Ultrasound-Induced Bubble Clusters in Tissue-Mimicking Agar Phantoms.

Therapeutic ultrasound can drive bubble activity that damages soft tissues. To study the potential mechanisms of such injury, transparent agar tissue-mimicking phantoms were subjected to multiple pressure wave bursts of the kind being considered specifically for burst wave lithotripsy. A high-speed camera recorded bubble activity during each pulse. Various agar concentrations were used to alter the phantom's mechanical properties, especially its stiffness, which was varied by a factor of 3.5. However, the maximum observed bubble radius was insensitive to stiffness. During 1000 wave bursts of a candidate burst wave lithotripsy treatment, bubbles appeared continuously in a region that expanded slowly, primarily toward the transducer. Denser bubble clouds are formed at higher pulse repetition frequency. The specific observations are used to inform the incorporation of damage mechanisms into cavitation models for soft materials.

Detection and Evaluation of Renal Injury in Burst Wave Lithotripsy Using Ultrasound and Magnetic Resonance Imaging.

PURPOSE: Burst wave lithotripsy (BWL) is a transcutaneous technique with potential to safely and effectively fragment renal stones. Preclinical investigations of BWL require the assessment of potential renal injury. This study evaluates the capabilities of real-time ultrasound and MRI to detect and evaluate BWL injury that was induced in porcine kidneys. MATERIALS AND METHODS: Ten kidneys from five female farm pigs were treated with either a 170 or 335 kHz BWL transducer using variable treatment parameters and monitored in real-time with ultrasound. Eight kidneys were perfusion fixed and scanned with a 3-Tesla MRI scanner (T1-weighted, T2-weighted, and susceptibility-weighted imaging), followed by processing via an established histomorphometric technique for injury quantification. In addition, two kidneys were separately evaluated for histologic characterization of injury quality. RESULTS: Observed B-mode hyperechoes on ultrasound consistent with cavitation predicted the presence of BWL-induced renal injury with a sensitivity and specificity of 100% in comparison to the histomorphometric technique. Similarly, MRI detected renal injury with a sensitivity of 90% and specificity of 100% and was able to identify the scale of lesion volumes. The injuries purposefully generated with BWL were histologically similar to those formed by shock wave lithotripsy. CONCLUSIONS: BWL-induced renal injury can be detected with a high degree of sensitivity and specificity by real-time ultrasound and post-treatment ex vivo MRI. No injury occurred in this study without cavitation detected on ultrasound. Such capabilities for injury detection and lesion volume quantification on MRI can be used for preclinical testing of BWL.