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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.

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

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.

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.