Shock Wave Technology and Application: An Update

Abstract

Context The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems. Objective To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies. Evidence acquisition We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy. Evidence synthesis Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60–80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures. Conclusions New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL.

CUA Guideline: Management of ureteral calculi

“…For mid to distal ureteric stones, where the renal parenchyma is not affected by SWL energy, treatment can safely be carried out up to 4000 or more shocks. 37 However, the incremental benefit of treating ureteric stones beyond 4000 shocks has not been established. For upper ureteral stones the range is from 2000 to 3500 shocks.…”

“…In general, if SWL fails it can be repeated, but the incremental benefit of more than two SWL treatments for the same ureteric stone is small. 36,37 Accordingly, after two unsuccessful SWL treatments, consideration should be given to alternative treatment with ureteroscopy. The optimal time interval between SWL treatments is unclear, but can be as short as within two days for mid and distal ureteric stones.…”

“…For upper ureteral stones the range is from 2000 to 3500 shocks. 37 In general, urologists should follow their lithotripter manufacturer's recommendations for the optimal maximum number of shocks. …”

Çocukluk Taş Hastalığında Extracorporeal Shock Wave Lithotripsy: Hala Yaşıyor ve Çok Etkili

“…Çünkü elektromanyetik jeneratörler daha küçük başlıklar-da yeterli şok dalga basıncı sağlayabilmekte, şok dalgaları daha kontrollü ve etkin olmaktadır. Bunun yanında elektrodu daha uzun ömürlü olup, odaklama alanının boyutu değiştirilebilmekte ve kolaylıkla çok fonksiyonlu modüler masalara adapte edilebilmektedirler (25). Endoüroloji'deki hızlı değişime ayak uydurma adına; SWL teknolojisinde de gelişme ve arayışlar sürmektedir.…”

Un nuevo enfoque terapéutico para la disfunción eréctil: las ondas de choque de baja intensidad

“…Las ondas de choque de baja intensidad son ondas acústicas longitudinales de transmisión continua con frecuencia entre 16 y 20 megaherzios y duración menor de 10 microsegundos, que generan un impulso de presión y transportan energía cuando se propagan a través de un medio (32). El grado de enfoque se puede modular de forma no invasiva, lo que resulta en una concentración variable de energía en la ubicación deseada.…”