Search

BACKGROUND: The extracorporeal shock wave lithotripsy (ESWL) is a non-invasive method in the treatment of urinary tract stones and its discovery has led to a complete change in the therapeutic strategy for urolithiasis. Due to the low morbidity and excellent fragmentation of the stones, ESWL has proven to be an effective and non-invasive method in the treatment of renal stones. AIM: The aim of this retrospective study is to evaluate the efficacy and safety of the ESWL as a monotherapy in the treatment of moderate size kidney stones with stone area (SA) of 100–300 mm². MATERIALS AND METHODS: We made a retrospective study of 98 patients with moderate size kidney stones with SA of 100–300 mm², divided into two subgroups, into a group with a SA of 100–200 mm² and with 200–300 mm², treated with ESWL in the period of November 2018–December 2019. The patients were treated with a third-generation electromagnetic lithotripter (Lithoskop®, Siemens Medical Systems, Erlangen, Germany), with a source of electromagnetic shocks (Pulso™) and dual ultrasonographic/fluoroscopic system for detection of the stones. The stone location, size, maximum energy used, localization technique, number of shock waves, sessions, re-treatment rate, and additional procedures were reviewed. All the patients before the intervention had a complete laboratory and radiological examinations. Postoperatively, patients were monitored on the 1st, 30th, and 90th post-operative days. RESULTS: Ninety-eight patients with solitary kidney stone with a SA of 100–300 mm² were treated with ESWL. The study included 58 men (59.18%) and 44 women (40.81%). The average length and width of the stone were 15.47 ± 2.68 mm and 12.99 ± 2.83 mm, respectively. The average surface area of the stones in our series was 203.78 ± 72.85 mm². The mean number of treatments for the entire series of patients was 1.82 ± 0.91. The mean number of shock waves for the total series of patients was 3899.11 ± 40. The mean energy used for the overall patient series was 110106.17 ± 21489.61 mJ. The total re-treatment rate was 47.95%. The entire rate of additional procedures was 19.38%. The overall success rate (SR) in our study was 77.55%. The efficiency quotient for the upper-middle and lower calyx was 55.57, 57.15, and 30.81, respectively. CONCLUSION: ESWL is a safe and effective method in the treatment of renal stones, and we recommend as the first method in the treatment of moderate size kidney stone with a surface area of 100–300 mm². The treatment of each patient should be individualized and take into account all favored and non-favored factors that influence the decision to choose extracorporeal lithotripsy as a method of treatment of medium-sized stones.

The effects of stone size on the process and comminution efficiency of shock wave lithotripsy (SWL) were investigated in experiments, numerical simulations and scale analysis. Cylindrical BegoStone phantoms with approximately equal height and diameter of either 4, 7 or 10 mm, in a total aggregated mass of about 1.5 g, were treated in an electromagnetic shock wave lithotripter field. The resultant stone comminution was found to correlate closely with the average peak pressure, P+(avg), incident on the stones. The P+(avg) threshold necessary to initiate stone fragmentation in water increased from 7.9 to 8.8 to 12.7 MPa, respectively, as stone size decreased from 10 to 7 to 4 mm. Similar changes in the P+(avg) threshold were observed for the 7- and 10-mm stones treated in 1,3-butanediol, in which cavitation is suppressed, suggesting that the observed size dependency is due to changes in stress distribution within stones of different size. Moreover, the slope of the correlation curve between stone comminution and ln(P¯+(avg)) in water increased with decreasing stone size, whereas the opposite trend was observed in 1,3-butanediol. The progression of stone comminution in SWL exhibited size-dependence: the 7- and 10-mm stones fragmented into progressively smaller pieces, whereas a significant portion (>30%) of the 4-mm stones reached a stalemate within the size range of 2.8 ∼ 4 mm, even after 1000 shocks. Analytical scaling considerations suggest size-dependent fragmentation behavior, a hypothesis further supported by numerical model calculations that reveal changing patterns of constructive and destructive wave interference and, thus, variations in the maximum tensile stress or stress integral produced in cylindrical and spherical stone of different sizes.

We have investigated the relationship between stone size and stone comminution (SC) in shock wave lithotripsy (SWL). Begostone phantoms of cylindrical shape in 4-, 7- and 10-mm size (W x H) groups were prepared with appropriately equal total mass (i.e., 1.5 g) in a tube holder and treated in an electromagnetic shock wave lithotripter field at various locations and doses. The results reveal a close correlation between SC and the average peak pressure, P+(avg), incident on the stone among differnet size groups. The P+(avg) threshold to initiate stone fragmentation and the slope of SC vs ln (P+(avg)) curve in water were found to increase with decreased stone size. In 1,3-butanediol where cavitation is suppressed, the P+(avg) threshold was found to be similar to the value in water yet the slope of the SC curve was significantly reduced at decreased stone size. Altogether, these results demonstrate a clear dependency of the P+(avg) threshold and rate of SC on stone size, as well as the importance of cavitation...

Kidney stones are a common and painful affliction, but fortunately physics offers some relief: Sound can be used to break up the stones, without invasive surgery. Efficacy of this ``lithotripsy'' treatment, however, depends strongly on cavitation, which can both attenuate the sound waves and provoke significant tissue damage. In this collaboration between a physicist, engineers, and materials scientists, our understanding of this process is advanced through measurements and modeling, providing insight into the relations between bubble dynamics and lithotripsy effectiveness.

The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens design for a contemporary electromagnetic (EM) shock wave lithotripter, based on recently acquired knowledge of the key lithotripter field characteristics that correlate with efficient and safe SWL. The new lens design addresses concomitantly three fundamental drawbacks in EM lithotripters, namely, narrow focal width, nonidealized pulse profile, and significant misalignment in acoustic focus and cavitation activities with the target stone at high output settings. Key design features and performance of the new lens were evaluated using model calculations and experimental measurements against the original lens under comparable acoustic pulse energy (E+) of 40 mJ. The −6-dB focal width of the new lens was enhanced from 7.4 to 11 mm at this energy level, and peak pressure (41 MPa) and maximum cavitation activity were both realigned to be within 5 mm of the lithotripter focus. Stone comminution produced by the new lens was either statistically improved or similar to that of the original lens under various in vitro test conditions and was significantly improved in vivo in a swine model (89% vs. 54%, P = 0.01), and tissue injury was minimal using a clinical treatment protocol. The general principle and associated techniques described in this work can be applied to design improvement of all EM lithotripters.

Objectives. To evaluate the incidence and outcome of cardiac arrhythmias associated with an external fixed-rate generator and the Medstone lithotripter with regard to stone location, anesthesia type, patient age, and gender. Methods. Data were obtained on 933 patients who underwent shock wave lithotripsy (SWL) with the Medstone lithotripter. Patients were randomly divided into two study groups, including those with pre-existing cardiac disease, hypertension, and cardiac medications. Group 1 (576 patients) were treated with the external fixed-rate signal generator (cardiac simulator). Group 2 (357 patients) underwent electrocardiogram-gated SWL (no simulator). All patients were monitored for arrhythmias during SWL. Patients who developed arrhythmias on the simulator were converted to gated SWL. Results. In group 1, 463 patients (80%) had no arrhythmias during treatment, whereas 113 patients (20%) developed cardiac arrhythmias (primarily premature ventricular contractions [PVCs]) and were successfully converted to gated SWL. Only 1 patient in group 2 (0.3%) had a documented arrhythmia (PVC). Group 1 patients who developed arrhythmias with a cardiac simulator were more likely to have renal rather than ureteral stones. Chi-square analysis showed a significant correlation between patients with and without arrhythmias in group 1 with regard to stone location (P

The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model.Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave treated kidneys were perfused, dehydrated, cast in paraffin wax and sectioned. Digital images were captured every 120 μm and processed to determine functional renal volume damage.After 500 shocks, the mean ± SD stone fragmentation efficiency produced by the original and modified lenses was 48% ± 12% and 52% ± 17%, respectively (p = 0.60). However, after 2,000 shocks, the modified lens showed significantly improved stone fragmentation compared to the original lens (mean 86% ± 10% vs 72% ± 12%, p = 0.02). Tissue injury caused by the original and modified lenses was minimal at a mean of 0.57% ± 0.44% and 0.25% ± 0.25%, respectively (p = 0.27).With lens modification the Modularis lithotripter demonstrates significantly improved stone fragmentation with minimal tissue injury at a clinically relevant acoustic pulse energy. This new lens design could potentially be retrofitted to existing lithotripters, improving the effectiveness of electromagnetic lithotripters.

Objective To assess whether the stone composition affects the operative time of ureteroscopic holmium:yttrium-aluminum-garnet laser lithotripsy (ULL) with active fragment retrieval. The chemical composition of a calculus is known to affect the efficacy with which it is fragmented by a device, such as pneumatic, laser, or shock wave lithotripter. Previous studies examining the efficacy of holmium:yttrium-aluminum-garnet laser lithotripsy have been performed in vitro, but it is not known whether the operative time is significantly affected by the chemical composition of a patient's stone. Methods We selected all patients who had undergone ULL for stone disease from July 2008 to January 2011 for a retrospective chart review. We used a standardized operative technique of fragmentation and active retrieval of all fragments identified on full inspection of the entire collecting system using rigid and flexible endoscopes. The stone composition was defined as the presence of a single predominant (>51%) component. Statistical analysis was performed on a per-procedure basis relative to the stone burden, as measured in minutes of operative time per gram of stone. Results A total of 187 cases of unilateral ULL with active retrieval of stone fragments confirmed to have a single predominant chemical composition met the inclusion criteria. When accounting for the weight of the recovered stone, no difference was found in the operative time among the apatite, brushite, cystine, calcium oxalate monohydrate, calcium oxalate dihydrate, and uric acid stones. Conclusion Although stone composition is widely recognized as an important procedural variable, especially for shock wave lithotripsy, it appears to have little effect on the overall operative time for holmium:yttrium-aluminum-garnet lithotripsy when using active fragment retrieval.

Objectives To compare the treatment efficacy of Dornier Compact S and a Chinese electromagnetic shock wave lithotripter (Huikang MZ-SWL-V) in a large series. Methods We retrospectively reviewed the outcome of shock wave lithotripsy (SWL) in 13,954 consecutive patients with upper urinary tract stones from December 1996 to December 2008 with Dornier Compact S (9124 cases) and Huikang MZ-SWL-V (4830 cases). An intramuscular injection of 50 mg pethidine was given to the patients with Dornier Compact S but not to those with Huikang MZ-SWL-V. Treatment outcomes were assessed by the stone-free rate at three months, the retreatment rate, the auxiliary procedure rate, and the effectiveness quotient. The pain scores were evaluated by visual analog scales, where 0 = pain and 10 = unbearable pain. Results The overall stone-free rate at 3 months, retreatment rate, and ancillary procedure rate for Dornier Compact S were 95.9%, 13.4%, and 2.2%, respectively, and they were 85%, 29.6%, and 10.2%, respectively, for Huikang MZ-SWL-V. The overall efficiency quotients of Dornier Compact S and Huikang MZ-SWL-V were 83% and 60.8%, respectively. However, the pain scores in the Dornier group (6-10) were higher than those in the Huikang group (1-5). Three clinically significant subcapsular hematomas were detected in the Dornier group but there were none in the Huikang group. Conclusions Dornier Compact S is more effective than Huikang MZ-SWL-V, but SWL with Huikang machine could be performed with milder pain and without analgesia, and a lower significant hematoma rate was observed in Huikang group.

The authors give account of the experience they gained with the Direx Tripter X-1 (ESWL) apparatus. In a random material they succeeded to render 81.5% of the patients stone free within three months. They judge the apparatus suitable for in situ treatment of pelvic and ureteric stones and for the monotherapy of staghorn calculi. It is easy to handle, inexpensive to buy and maintain but noisy to operate, moreover the patient has to be anaesthetized. All in all it is highly useful in the treatment of renal lithiasis.

Twenty-eight patients with lower ureteral stones underwent in situ extracorporeal shock wave lithotripsy (ESWL) in the prone position over the period of 7 months between March 1990 and September 1990. For stone disintegration the spark gap shock wave lithotripter Tripter XI (Direx) was used. Satisfactory disintegration was achieved in 93 per cent of patients. The stone-free rate at 12 weeks was 82 per cent, and 11 per cent had residual fragments less than or equal to 4 mm in diameter. Twenty-one per cent of patients required repeat treatments. For only 2 patients general anaesthesia was required (7 per cent). There were no remarkable complications except for haemospermia which resolved spontaneously 15 days after treatment. It was concluded that in situ prone ESWL is an effective and safe procedure for the treatment of lower ureteral stones.

A total of 65 patients with 67 upper ureteral stones underwent in situ extracorporeal shock wave lithotripsy (ESWL) between March 1990 and September 1990. For stone disintegration the electrohydraulic shock wave lithotripter Tripter XI (Direx) was used. Eighty-seven per cent of stones showed satisfactory disintegration after the first treatment and a further 9 per cent after repeat treatments. The stone-free rate at 12 weeks was 85 per cent. General anaesthesia was needed in only 12 per cent of patients. The retreatment rate was 13 per cent. It was concluded that in situ ESWL is an effective procedure with negligible morbidity for treating upper ureteral stones.

In this paper we have reviewed the feasibility of using a shock wave lithotripter to loosen the interface between the bone and acrylic bone cement for revision arthroplasty. We have reviewed the physics of shock wave and its applications in medicine, especially its interaction with tissues. The calculations show that the energy is greatly reduced at the interface both in the soft tissue–bone interface and cement–bone interface. On the other hand, a tensile and compressive pressure can be operated at the cement–bone interface that can cause the interface to break if the pressure exceeds the tensile strength of the cement–bone interface. Subsequent papers will deal with in vitro and in vivo application of the shock wave in the treatment of the cement-bone interface in order to weaken it and consequently for easier extraction of bone cement from the intramedullary canal.

Despite recent innovations in lithotripter design and technology, the first generation Dornier HM-3 electrohydraulic lithotripter remains the most effective clinical, non-invasive modality for comminuting stones. Understanding the fundamental differences between the HM-3 and more clinically practicable lithotripters is critical to achieving meaningful improvements in future models. This study aims to further clarify the role of the second, weaker pulse of the HM-3 in stone comminution by introducing a similar pulse in the pressure profile of an electromagnetic lithotripter. Additionally, this study investigates the potential for this tandem shock technique to improve comminution in electromagnetic lithotripters through optimization of the interpulse delay time.

The effects of respiratory motion on stone comminution produced by an electromagnetic (EM) shock wave lithotripter were evaluated in vitro. Individual spherical BegoStone phantoms (D = 10 mm) were placed in a flat‐base tube holder and treated at various radial distances in the lithotripter focal plane. To assess the effects of respiratory motion on stone comminution, the holder was set into translational motions in another series of experiments with various excursion distances (1.5–3.0 cm), breath rates (12–24 bpm), and drift factors for motion randomization. Stone comminution tests were performed using either a newly designed acoustic lens with a wide focal width and a low peak pressure or the original lens under equivalent acoustic energies. The results shows that the new lens produces statistically higher stone comminution (p < 0.01) than the original lens. Moreover, stone comminution at various radial distances will be compared, together with cavitation potential calculated by the Gilmore model based ...

NAG and -2 microglobulin. After SWL, all group showed similar CCr. Compared with the sham group, control and COX-2 groups produced increase of NAG and -2 microglobulin excretion. However, NAG and -2 microglobulin excretions were significantly lower in the COX-2 group than control group. The mean grade of tubular injury of the COX-2 group was significantly lower than the control group. The COX-2 gene expression did not increase in the sham group. However, the COX-2 gene expression was significantly increased in the control group, which was prevented by celecoxib in COX-2 group. CONCLUSIONS: SWL increased COX-2 gene expression in renal tissues and COX-2 inhibition reduced renal tubular injury after SWL. Biochemical and histological findings also supported a renal protective effect of celecoxib on SWL.

Stone breakage is less efficient when lithotripter shock waves (SWs) are delivered at 2 Hz compared to slower 0.5–1‐Hz pulse repetition rates (PRFs). This correlates with increased number of transient cavitation bubbles observed along the SW path at fast PRF. The dynamics of this bubble proliferation throughout the bubble lifecycle is investigated in this report. Cavitation bubbles were studied in the free‐field of a shock wave lithotripter using fine temporal and microscopic spatial resolution (high‐speed camera Imacon‐200). A typical cavitation bubble became visible (radius>10 μm) under the tensile phase of the lithotripter pulse, and at its first inertial collapse emitted a secondary SW and formed a micro‐jet, which then could break up forming ∼25 micro‐bubbles. Subsequent rebound and collapse of the parent bubble appeared to produce a further 40–120 daughter bubbles visible following the rebound. Preexisting bubbles hit by the lithotripter SW also formed micro‐jets and broke up into micro‐bubbles that...

Objectives: To evaluate the success of shock wave lithotripsy (SWL) as monotherapy for solitary renal stones larger than 2 cm without ureteral stenting. Hence, if our study result demonstrates acceptable success and safety, we can recommend ESWL as a treatment option for patients with large renal calculi. Subjects and methods: This is a prospective study conducted in the Department of Urology, Regional Institute of Medical Sciences, Imphal, India, from January 2011 to December 2012. A total of 104 patients aged between 20 and 70 years with solitary large (>2 cm) renal stones underwent ESWL using the Dornier Compact Sigma Lithotripter. Stone size was calculated by measuring the largest dimension of the stone in KUB plain films. In each session, 3000–3500 shocks at frequency 60–90 min−1 and intensity between 1 and 4 were given. A maximum number of six sessions were given. Successful treatment was defined as complete clearance or residual stones smaller than 4 mm on KUB performed 3 months after the first session. Results: Total number of patients was 104. The M:F ratio was 1:1.4. The stone size ranged from 21 to 55 mm. The overall success rate was 73%. For stones >30 mm, the success rate was only 62.2% (n = 28). The number of sessions required increased as the stone size increased. The most common complication encountered was haematuria. Conclusion: ESWL remains the cornerstone of therapy for renal calculi less than 2 cm. Our study reveals that multiple sessions were required for solitary renal calculi, with higher rate of ancillary procedures. The success rate of ESWL for both non-staghorn and staghorn calculi with size above 2 cm is low, so other treatment modalities like PCNL should be considered as the first treatment option. However, with appropriate patient selection, significant improvements in stone-free rates may be achieved.