Extracorporeal Shock Wave Lithotripter Research Articles

Clinical application of Sonolith 2000 type B on extracorporeal shock wave lithotripsy for upper urinary tract calculi

This report describes the results of clinical trials of the second generation extracorporeal shock wave lithotriptor (Sonolith 2000 Type B) in patients with upper urinary tract stones. The studies were carried out on 101 cases at the Departments of Urology, Juntendo University School of Medicine, Kanto Teishin Hospital and General Daiyukai Hospital from Nov. 1987 to Jun. 1988. The location of stones were renal calyx and pelvis in 84 cases, ureteropelvic junction in 7 cases and upper ureter in 12 cases (2 of them had multiple stones at different levels). The average number of treatment per a patient was 1.25, and that of shock waves delivered per treatment was 1798. Ultrasound localization has been effective in all cases. The rate of destruction of the stones was 100% in the kidney, 66.7% in the upper ureter, with an overall average of 95.0%. On the X-ray film obtained six weeks after ESWL treatment, the stone free rate was 53.5%, and the effectiveness rate was 89.1%, including the cases of stone free and cases with fragments smaller than 5 mm. No serious adverse effect was observed, although there were mild transient hematuria in all cases and pyrexia (more than 38.0 degrees C) in 7 cases (6.9%). The procedure was performed safely in the majority of patients without anesthesia. In 10 cases, we applied anesthesia (epidural anesthesia in 3 cases, and local anesthesia in 7 cases) for the prevention of pain. It is concluded that ESWL treatment using Sonolith 2000 Type B is as effective as other types of shock wave lithotriptor previously applied to urolithiasis without serious clinical complication.

Extracorporeal shock wave lithotripsy for upper urinary tract stone using piezoelectric lithotripter (Piezolith 2200)

The results of clinical trial using the second generation extracorporeal shock wave lithotripter (Piezolith 2200, Wolf, West Germany) were presented. The treatments were performed between December 1987 and March 1988 at the University of Tokyo. In total 59 ESWL sessions were carried out on 32 patients with 48 upper urinary tract stones. The treatment could be performed without anesthesia or analgesic agent in every case. A double-J ureteral stent was indwelling in 6 patients with ureteral stones or large stones before ESWL treatment, and transurethral lithotripsy (TUL) was performed in two patients after the treatment. On the X-ray film obtained three weeks after the final ESWL treatment, 13 cases (40.6%) were completely free from stone fragments, while 9 cases (28.2%) had stone fragments less than or equal to 5 mm. Others had fragments greater than 5 mm. ESWL using this device was clinically useful in 71.9% in the three weeks follow-up period. No serious complication was observed after treatment except macroscopic hematuria for a few days in all cases, pyrexia in 4 cases (12.5%) and flank pain in 7 cases (21.9%). There were slight and transient changes in the laboratory data after the treatment, but these changes were milder than those with spark gap lithotripters. It is concluded that Piezolith 2200 is useful in the management of patients with upper urinary tract stones, and it is applicable more safely than the first generation lithotripters.

Cavitation Microjets as a Contributory Mechanism for Renal Calculi Disintegration in Eswl

The rarefaction shock wave produced by an extracorporeal shockwave lithotripter can result in liquid failure at numerous discrete sites near the second focus. When the liquid fails, vapor-filled cavities can grow to relatively large sizes and subsequently collapse with enormous violence. This phenomenon, called acoustic cavitation, has been shown to cause severe erosion in materials exposed to cavitation fields. It is proposed in this paper that ESWL devices generate acoustic cavitation in vivo and that the high speed liquid microjets produced during cavitation bubble collapse play an important role in renal calculi disintegration.

The Effect of the Extracorporeal Shock Wave Lithotriptor on the Bone-Cement Interface in Dogs

The extracorporeal shock wave lithotriptor (ECSWL) is a machine that generates shock waves that transfer energy through biologic materials. This study focused the wave at a composite bone-cement (polymethylmethacrylate) interface and evaluated the effects both quantitatively and qualitatively. Six matched sets of dog femora were selected. The intramedullary canals were packed uniformly with cement. One of the set was randomly selected for treatment with impulses while the other served as the control. The bone was then sectioned transversely into discs, and scanning electron microscopy and mechanical push-out studies were performed. The results indicated that the ECSWL does have a loosening effect on the bone-cement interface. Using a paired Student's t-test, the shear strength was significantly less in the treated group than in the control (p less than 0.003). Microscopically, the treated specimens revealed relative sparing of the surrounding bone. At the bone-cement interface, however, microfractures, loose bodies, and widening were seen. Revision total arthroplasty has a significant morbidity, which can be partially attributed to cement extraction. The results of this study indicate that the ECSWL may be a useful adjunct in revision surgery by facilitating the extraction of polymethylmethacrylate and thereby reducing the morbidity.

Treatment of paediatric urolithiasis by extracorporeal shock-wave lithotripsy.

Non-surgical removal of renal and ureteral stones has proven successful in adults. In this study, 21 paediatric patients have been treated with the first generation extracorporeal shock-wave lithotriptor and an additional 13 children with a second generation local shock-wave lithotriptor. A total of 47 stones was treated. Treatment-related complications such as colics (17%/18.8%) or fever (8.3%/6.2%) were minimal. Stone passage occurred in 93% and 100%, respectively of each group. Open surgery is still the treatment of choice for large staghorn calculi. Extracorporeal shock-wave lithotripsy can be performed successfully in paediatric nephrolithiasis with stones of limited size.

A theoretical study of cavitafion generated by an extracorporeal shock wave lithotripter

The intense acoustic wave generated at the focus of an extracorporeal shockwave lithotripter is modeled as the impulse response of a parallel RLC circuit. The shock wave consists of a zero rise time positive spike which falls to 0 at 1 μs followed by a negative pressure component 6 μs long with amplitudes scaled to + 1000 and − 167 bars, respectively. This pressure wave drives the Gilmore‐Akulichev formulation for bubble dynamics; the zero order effect of gas diffusion on bubble response is included. Results predict that a preexisting bubble in the micron range will expand to over 100 times its initial size, R0, for 240 μs, with a peak radius of 1350R0, then collapse very violently, emitting far UV or soft x‐ray photons (black body assumption). Gas diffusion does not appreciably mitigate the violence of the primary collapse, but does significantly increase R0, up to 40 μm, as well as the duration of subsequent ringing, assuming no break up or production of microbubbles. The prediction of x‐ray emission is of more academic than clinical concern because relatively few photons will be produced, and renal tissue exhibits a fairly low radio‐sensitivity. [Work supported by NIH.]

A comparison of commercial extracorporeal shock wave lithotripters based on measurements in the acoustic field

A survey of five, presently available, commercial extracorporeal shock wave lithotripters is reported. As part of the survey, a detailed examination of the acoustic field of the Dornier HM3, Wolf Piezolith 2200, Technomed Sonolith 2000, EDAP LT‐01, and Siemens Lithostar was carried out using the same 25‐μm, bilaminar PVDF membrane hydrophone. The absolute pressure has been estimated from the voltage waveforms (recorded on a digital scope with a 30‐MHz single‐shot bandwidth) using the 1‐MHz calibration factor for the hydrophone. The peak positive focal pressure at clinically used power settings of the different lithotripters is found to vary in the range 20–115 MPa. The peak negative focal pressure ranges from 3–10 MPa. The width of the focal region (defined as the region in which the peak positive pressure may be greater than 50% of that at the focus) varies from 0.1–2.5 cm. The rise time of the main pressure peak (defined as the time from 10%–90% of the peak positive pressure) is found to vary from less than 30 ns to 500 ns and the full width at a half‐maximum of the positive pressure half‐cycle from 250–500 ns. The estimated peak positive pressure gain of the different systems range from 10 to above 1000. Some of the parameters reported can be related to the relative clinical performance of the lithotripters. [Thanks to the companies and hospitals who provided the facilities for this survey.]

Results in the Use of Extracorporeal Piezoelectric Lithotripsy (EPL) for Treatment of Urinary Calculi

The Piezolith 2200 as an extracorporeal shock wave lithotripter uses piezoelectrically generated, high-energy sonic impulses for treatment of urinary calculi; the shock wave generator is self-focussing. Localization of concrements is performed by means of ultrasound imaging. Treatment with the Piezolith 2200 is painless for the patient and thus possible without anesthesia and analgesia. We report on 806 cases of treatment involving a total of 572 kidneys in 567 patients (561 adults, 6 children) suffering from calculi of various sizes in the renal pelvis (n = 126), calculi in the calyces (n = 384), partial (n = 24) or full (n = 19) staghorn calculi, as well as calculi in the upper part of the ureter (n = 19). In 88% of these cases the concrements could be removed completely. Since cardiac activity is not influenced by piezoelectrically generated high-energy impulses, this procedure is particularly suited to the treatment of patients with heart problems.

Methodology, results and complications in 2000 extracorporeal shock wave lithotripsy procedures.

Since the installation of an extracorporeal shock wave lithotriptor (ESWL) unit 12 months ago, 2000 lithotripsy procedures have been performed. Overall, 68.4% of patients were stone-free by the end of the first month. Residual lithiasis (fragments less than 0.5 cm) was seen in 19.7% of patients and significant lithiasis (fragments greater than 0.5 cm) was observed in 10.1%. Complications were obstruction, infection, headache due to the epidural anaesthesia, anuria, renal failure, perirenal haematoma and cardiac arrest. A number of patients required additional operative treatment; this was always endoscopic and no open procedures were performed. Hospitalisation averaged 1 day.

Patient Exposure and Radiation Environment of an Extracorporeal Shock Wave Lithotriptor System

Radiation exposures to the patient undergoing extracorporeal shock wave lithotripsy were assessed along with the scattered radiation levels around the lithotriptor systems. The data gathered from 2 Dornier lithotriptor systems suggest that the lead shieldings required for this particular make and model are minimal. Owing to the physical size of the lithotriptor system, the treatment room housing it may not require additional lead shielding when the walls are constructed with appropriate materials. Typical radiation exposures to the patient have been assessed from the experimental data. The total amount of radiation exposures a patient is likely to receive has been estimated to be approximately 26 roentgens, for example 21 roentgens from 3 to 4 minutes of fluoroscopic exposure and 5 roentgens from 8 frames of video spot filming. The scattered radiation has been found to be approximately 0.5mR. per hour at 3 feet or 91cm. from the center of the lithotriptor water tank.

Pressure waveforms generated by a Dornier extra-corporeal shock-wave lithotripter.

Pressure waveforms in the acoustic field generated by a Dornier (HM3) shock-wave lithotripter have been measured using a bilaminar shielded PVDF membrane hydrophone in water. Using these waveforms, values of the peak-positive (p+) and peak-negative pressure (p-) at various positions in the field have been estimated. At the focus, p+ is 38.6 MPa (standard deviation = 9.0 MPa) and p- is 10.1 MPa (standard deviation = 1.0 MPa) at 20 kV discharge potential and an electrode separation in the range 1.3 to 2.4 mm. The peak-positive pressure is found to fall to 50% (-6 dB level) at about 60 mm either side of the focus on the major axis of the reflector and on a 10 mm radius circle around the focus in the focal plane. A shot-to-shot variation of +/- 25% in p+ is attributed to the inherent variability of the electrical discharge which may result in changes in the exact position and strength of the acoustic field. The results reported are considered to be more accurate than those of previous measurements due to the relatively flat frequency response of this type of hydrophone.

The Effects of Extracorporeal Shock Wave Lithotripsy on Pacemaker Function

Twenty-two pacemaker pulse generators were exposed to shock waves of an extracorporeal shock wave lithotripter to assess the effects of the extremely high pressure transients on pacemaker function. The pulse generator and distal aspect of the lead were positioned 5 cm from the focal point of the lithotripter and 10 cm from each other. Pulse generator function was analyzed during shock wave delivery synchronized with pulse generator output, during shock waves at a rate faster than the escape rate, and after exposure to lithotripsy. During shock waves delivered synchronously with pulse generator output, only one of 22 pulse generators malfunctioned by intermittently reverting to the magnet rate. When subjected to shock waves at a rate greater than the escape rate, 50% of the pulse generators were inhibited by electromechanical interference from the lithotripter. Both bipolar and unipolar devices were affected. However, analysis after exposure to shock waves showed that none of the pacemakers was damaged or spuriously reprogrammed. In conclusion, cardiac pacemakers do not appear to be damaged or reprogrammed by exposure to extracorporeal shock wave lithotripsy. The likelihood of false inhibition appears to be very low if shock waves are delivered synchronously with the QRS.

716 - Experience with the First Extracorporeal Shock Wave Lithotripter Unit in Canada

No AccessJournal of Urology1 Jun 1987Experience with the First Extracorporeal Shock Wave Lithotripter Unit in Canada Martin G. McLoughlin, Seek L. Chan, V. Allen Rowley, Joachim H. Burhenne, and Edward A. Gofton Martin G. McLoughlinMartin G. McLoughlin More articles by this author , Seek L. ChanSeek L. Chan More articles by this author , V. Allen RowleyV. Allen Rowley More articles by this author , Joachim H. BurhenneJoachim H. Burhenne More articles by this author , and Edward A. GoftonEdward A. Gofton More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(17)75866-1AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "Experience with the First Extracorporeal Shock Wave Lithotripter Unit in Canada." The Journal of Urology, 137(6), p. 283A © 1987 by The American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 137Issue 6June 1987Page: 283A Advertisement Copyright & Permissions© 1987 by The American Urological Association Education and Research, Inc.MetricsAuthor Information Martin G. McLoughlin More articles by this author Seek L. Chan More articles by this author V. Allen Rowley More articles by this author Joachim H. Burhenne More articles by this author Edward A. Gofton More articles by this author Expand All Advertisement Loading ...

Acoustic cavitation generated by an extracorporeal shockwave lithotripter

Evidence is presented of acoustic cavitation generated by a Dornier extracorporeal shockwave lithotripter. Using x-ray film, thin aluminium sheets, and relatively thick metal plates as targets, evidence of liquid jet impacts associated with cavitation bubble collapse was observed. The jet impact was violent enough to puncture thin foils and deform metal plates. Furthermore, numerous jet impacts were generated over a volume of greater than 200 cm 3. It is likely that such violent cavitation will also occur in tissue, and observed biological effects (e.g. renal calculus disintegration and tissue trauma) may be related to cavitation damage.

Clinical study of urinary tract infection after treatment with extracorporeal shock-wave lithotriptor. Extracorporeal shock-wave lithotriptor

Clinical study of urinary tract infection after treatment with extracorporeal shock-wave lithotriptor. Extracorporeal shock-wave lithotriptor

Acoustic cavitation generated by an extracorporeal shockwave lithotripter

Evidence is presented of acoustic cavitation generated by a Dornier extracorporeal shockwave lithotripter. Using x‐ray film, thin aluminum sheets, and relatively thick metal plates as targets, evidence of liquid jet impacts associated with cavitation bubble collapse was observed. The jet impact was violent enough to puncture thin foils and deform metal plates. Furthermore, numerous jet impacts were generated over a volume greater than 200 cm3. It is likely that such violent cavitation will also occur in tissue, and observed biological effects, e.g., renal calculus disintegration and tissue trauma, may be related to cavitation damage. [Work supported in part by the ONR, NIH, NSF, and the Fulbright Commission.]

Ultrasound stone localisation for extracorporeal shock wave lithotripsy.

An extracorporeal shock wave lithotriptor using an ultrasound scan head pantograph location system has been designed. The shock wave ellipsoid reflector position is adjusted to the stone with a computer assisted positioning device. Seven dogs with stones implanted into the renal pelvis were treated and stone fragmentation occurred in all cases. Subsequently, 45 patients with stones were treated. The stones ranged in size from 5 to 29 mm (mean 16). Radio-opaque as well as poorly opaque or radiolucent stones were treated and fragmentation was achieved in 85% of cases. An additional endoscopic procedure was performed in four cases. No fragmentation occurred in four patients. Further shock wave treatment was necessary in two patients who presented with stones larger than 2 cm. Both radio-opaque and poorly opaque stones can be treated with this system. Ultrasound localisation and the ellipsoid positioning device avoid the need for expensive fluoroscopic equipment and a hydraulic patient positioning system.

The use of ultrasound for the investigation of aqueous suspensions of natural non-oxide pigments: Ryumin, V. P.Zh. prikladnoi khimii, 35, no. 1, p. 56 (1962)

The acoustic emission from cavitation in the field of an extracorporeal shock wave lithotripter has been studied using a lead zirconate titanate piezoceramic (PC4) hydrophone in the form of a 100-mm diameter focused bowl of 120-mm focal length. With this hydrophone directed at the beam focus of an electrohydraulic lithotripter radiating into water, it is possible to identify signals well above the noise level, at the 1-MHz resonance of the hydrophone, which originate at the beam focus. Light emission, attributed to sonoluminescence, is also shown to originate at the focal region of the lithotripter, and the signal obtained from a fast photomultiplier tube directed at the focus has similarities in structure and timing to the detected acoustic signals. The multiple shock emission resulting from a single discharge of an electrohydraulic source is shown to result in two separate bursts of cavitational activity separated by a period of 3–4 ms. The signal burst corresponding to the primary shock has a duration of about 600 μs with little noticeable structure. The signal burst associated with the secondary shock has a reproducible structure with two distinct peaks separated by about 200 μs depending on the shock amplitude. The timing and structure of each burst is shown to be in reasonable agreement with the theoretical predictions made by Church (1989) based on the Gilmore model of bubble dynamics. In particular, it is shown that it is possible to obtain precise measurements of the time delay between the separate peaks within the signal burst detected following the secondary shock and this may, as predicted, provide a method of determining the size of bubbles remaining after the primary shock.