Current status of extracorporeal shock wave lithotripsy

Chaussy, C.; Wilbert, D. M.

doi:10.1007/s001200050089

Cited by 14 publications

(10 citation statements)

References 35 publications

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“…This technical improvement, if confirmed in vivo and in clinics, could reduce the adverse effects and broaden the application scope of SWL, especially for those who are at much higher risk for SWL-induced chronic injury, such as elderly patients. 7,33 Disintegration of renal calculi by SWL is a consequence of dynamic fracture of calculus caused by the growth and the coalescence of stress wave-induced microcracks (spalling, squeezing, and tear) inside the brittle stone, 1 and cavitation erosion on the exterior surface of calculus caused by the violent collapse of bubble cavitation (secondary shockwave or a liquid microject) 1,25,34 in a synergistic way. 28 Initially, stress waves dominate in breaking up kidney stones into distributed pieces.…”

Section: Discussionmentioning

confidence: 99%

“…1 Despite its great success and the development of several generations of clinical lithotripters with friendly user interface, better imaging quality, less anesthesia requirement, multifunctionality, and sometimes, high cost-effectiveness for stone treatment in the past three decades, no fundamental improvement in SWL technology has been accomplished. 2 In particular, there is substantial evidence from both clinical and basic studies that SWL produces acute renal injury, such as hematuria, kidney enlargement, renal and perirenal hemorrhage, and hematomas.…”

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confidence: 99%

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Reduction of Bubble Cavitation by Modifying the Diffraction Wave from a Lithotripter Aperture

Zhou

2012

Journal of Endourology

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Purpose: A new method was devised to suppress the bubble cavitation in the lithotripter focal zone to reduce the propensity of shockwave-induced renal injury. Materials and Methods: An edge extender was designed and fabricated to fit on the outside of the ellipsoidal reflector of an electrohydraulic lithotripter to disturb the generation of diffraction wave at the aperture, but with little effect on the acoustic field inside the reflector. Results: Although the peak negative pressures at the lithotripter focus using the edge extender at 20 kV were similar to that of the original configuration (-11.1 -0.9 vs -10.6 -0.7 MPa), the duration of the tensile wave was shortened significantly (3.2 -0.54 vs 5.83 -0.56 ls, P < 0.01). There is no difference, however, in both the amplitude and duration of the compressive shockwaves between these two configurations as well as the -6 dB beam width in the focal plane. The significant suppression effect of bubble cavitation was confirmed by the measured bubble collapse time using passive cavitation detection. At the lithotripter focus, while only about 30 shocks were needed to rupture a blood vessel phantom using the original HM-3 reflector at 20 kV, no damage could be produced after 300 shocks using the edge extender. Meanwhile, the original HM-3 lithotripter at 20 kV can achieve a stone comminution efficiency of 50.4 -2.0% on plaster-of-Paris stone phantom after 200 shocks, which is comparable to that of using the edge extender (46.8 -4.1%, P = 0.005). Conclusions: Modifying the diffraction wave at the lithotripter aperture can suppress the shockwave-induced bubble cavitation with significant reduced damage potential on the vessel phantom but satisfactory stone comminution ability.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Reduction of Bubble Cavitation by Modifying the Diffraction Wave from a Lithotripter Aperture

Zhou

2012

Journal of Endourology

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“…That is, there is a tremendous variability of stone fragility within all types of stone [18]. So, knowing that a stone is composed primarily of COM indicates that it may be difficult to break, but certainly many COM stones respond quite well to SWL [19]. Thus, knowing that a stone is composed primarily of COM really does not help in making decisions about treatment.…”

Section: Introductionmentioning

confidence: 97%

Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL)

Williams¹,

Zarse²,

Jackson³

et al. 2007

AIP Conference Proceedings

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Great variability exists in the response of urinary stones to SWL, and this is true even for stones composed of the same mineral. Efforts have been made to predict stone fragility to shock waves using computed tomography (CT) patient images, but most work to date has focused on the use of stone CT number (i.e., Hounsfield units). This is an easy number to measure on a patient stone, but its value depends on a number of factors, including the relationship of the size of the stone to the resolution (i.e., the slicewidth) of the CT scan. Studies that have shown a relationship between stone CT number and failure in SWL are reviewed, and all are shown to suffer from error due to stone size, which was not accounted for in the use of Hounsfield unit values. Preliminary data are then presented for a study of calcium oxalate monohydrate (COM) stones, in which stone structure -rather than simple CT number values-is shown to correlate with fragility to shock waves. COM stones that were observed to have structure by micro CT (e.g., voids, apatite regions, unusual shapes) broke to completion in about half the number of shock waves required for COM stones that were observed to be homogeneous in structure by CT. This result suggests another direction for the use of CT in predicting success of SWL: the use of CT to view stone structure, rather than simply measuring stone CT number. Viewing stone structure by CT requires the use of different viewing windows than those typically used for examining patient scans, but much research to date indicates that stone structure can be observed in the clinical setting. Future clinical studies will need to be done to verify the relationship between stone structure observed by CT and stone fragility in SWL.

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“…The main advantage of this procedure consists in avoiding surgery altogether by generating shockwaves extracorporeally and focusing them onto kidney stones [2]. As a result, the stones are broken into fragments small enough that they can be passed naturally by the human body.…”

Section: Introductionmentioning

confidence: 99%

Non-Spherical Collapse of an Air Bubble Subjected to a Lithotripter Pulse

Johnsen

Colonius

Kreider

et al. 2007

Volume 2: Biomedical and Biotechnology Engineering

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Seattle, Washington 98105 wkreider@u.washington.eduIn order to better understand the contribution of bubble collapse to stone comminution in shockwave lithotripsy, the shockinduced and Rayleigh collapse of a spherical air bubble is investigated using numerical simulations, and the free-field collapse of a cavitation bubble is studied experimentally. In shock-induced collapse near a wall, it is found that the presence of the bubble greatly amplifies the pressure recorded at the stone surface; the functional dependence of the wall pressure on the initial standoff distance and the amplitude are presented. In Rayleigh collapse near a solid surface, the proximity of the wall retards the flow and leads to a more prominent jet. Experiments show that re-entrant jets form in the collapse of cavitation bubbles excited by lithotripter shockwaves in a fashion comparable to previous studies of collapse near a solid surface.

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Current status of extracorporeal shock wave lithotripsy

Cited by 14 publications

References 35 publications

Reduction of Bubble Cavitation by Modifying the Diffraction Wave from a Lithotripter Aperture

Reduction of Bubble Cavitation by Modifying the Diffraction Wave from a Lithotripter Aperture

Using Helical CT to Predict Stone Fragility in Shock Wave Lithotripsy (SWL)

Non-Spherical Collapse of an Air Bubble Subjected to a Lithotripter Pulse

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