Shock Wave Lithotripsy Treatment Research Articles

Predictive Risk Factors for Pain During Extracorporeal Shockwave Lithotripsy

Extracorporeal shockwave lithotripsy (SWL) is a noninvasive but painful procedure. The aim of this study was to identify predictive risk factors for pain during SWL. Two hundred twenty-two SWL treatments with the Lithostar lithotripter (Siemens) were included in a monocentric study. Patient and stone characteristics were prospectively collected in a database, and a standardized pain control protocol was administered 1 hour before treatment: paracetamol, nefopam, ketoprofen, and alprazolam. Subjective pain level was assessed with visual analog scale (VAS, 0-10). If VAS was >or=3, tramadol was added. If VAS was still >or=3, shockwave intensity was decreased or treatment was interrupted. The efficacy on stone fragmentation was evaluated 1 month after treatment. The need for adjuvant analgesia was compared with patient and stone characteristics to find out predictive risk factors for pain. The average subjective pain was 3.1. The need for supplementary analgesia was more frequent in women (p = 0.035), younger patients (p < 0.001), anxious and depressed patients (p = 0.018), in patients with previous SWL (p = 0.0185), in patients with a rib projected stone (p < 0.001), in patients with renal stones (p = 0.0535), and finally in patients with homogeneous stones (p = 0.02). Multivariate analysis revealed two independent risk factors for pain: young age (odds ratio = 5; p < 0.001) and rib projected stone (odds ratio = 5.23; p < 0.001). Stone fragmentation was worse in patients with an adjuvant analgesia requirement (p = 0.0311). Predictive risk factors for pain during SWL treatments were found: young age, rib projected stones, anxious and depressed patients, previous SWL treatment, and homogeneous stones. A higher analgesic requirement is necessary for these preselected patients to perform SWL and optimize its efficacy.

UP-3.185: Salvage Extracorporeal Shockwave Lithotripsy (ESWL) Treatment after Initial Lithotripsy Failure by Semirigid Ureteroscopy

To evaluate the efficacy of salvage extracorporeal shockwave lithotripsy after initial lithotripsy failure by semirigid ureteroscopy.

The role of energy density and acoustic cavitation in shock wave lithotripsy

Today a high percentage of urinary stones are successfully treated by extracorporeal shockwave lithotripsy (SWL); however, misconceptions regarding fragmentation mechanisms, as well as treatment parameters like dose, applied energy and focal area are still common. A main stone comminution mechanism during SWL is acoustic cavitation. The objective of this study was to analyze the influence of cavitation and energy density on stone fragmentation. A research lithotripter was used to expose a large set of artificial kidney stones to shock waves varying different parameters. Hundreds of pressure records were used to calculate the energy density of the lithotripter at different settings. Results indicate that energy density is a crucial parameter and that better SWL treatment outcomes could be obtained placing the calculus at a prefocal position.

Treatment Time Reduction Using Tandem Shockwaves for Lithotripsy: AnIn VivoStudy

Reducing extracorporeal shockwave lithotripsy (SWL) time by increasing the shockwave rate of the lithotripter has been tested in the past; however, basic research and treatment outcomes revealed that this is not convenient. The purpose of this study was to use an animal model to demonstrate that SWL treatment time can be reduced significantly without sacrificing stone fragmentation efficiency using tandem shockwaves. A tandem research lithotripter was used to treat 50 artificial kidney stones implanted into the kidneys of 50 rabbits. Standard single-pulse and tandem shockwaves were compared in two different scenarios: Without a fluid-filled expansion chamber and with a fluid-filled expansion chamber surrounding the stone. The presence of fluid surrounding the stone enhances fragmentation in both the standard and tandem modes. No significant difference in fragmentation efficiency was recorded between the standard and tandem SWL with stones surrounded by fluid; however, the treatment time with tandem shockwaves was reduced by 50%. Significantly shorter SWL treatments may be possible in the future using tandem shockwaves on urinary stones that are surrounded by fluid.

Use of traditional Chinese medicine in the management of urinary stone disease

To assess the evidence-based literature supporting the use of traditional Chinese medicine Kampo herbal and Acupuncture in stone disease management. Four of the most commonly used herbal components of Kampo medicine in the treatment of stone disease are described according to their in vitro and in vivo effects. We also reviewed the role of Acupuncture in urologic clinical setting as well as its proposed mechanisms of action and results. Medline database was assessed using isolated and conjugated key words (Chinese Medicine, Kampo, Chinese Herbal, Calculi, Stone Disease, Kidney, Acupuncture, Herbal Medicine). Articles were reviewed and summarized. Herbal medicine has been proven to be free from side-effects and therefore suitable for long term use therapy. Its antilithic beneficial effects include increased urinary volume, increased magnesium excretion (Takusya), inhibitory activity on calcium oxalate aggregation (Takusya, Wulingsan and Desmodyum styracyfolium), inhibition of calcium oxalate nucleation and hydroxyapatite internalization (Wulingsan). In contrast, acupuncture, has shown to be effective as a pre-treatment anxiolytic and analgesic during colic pain and extracorporeal shock wave lithotripsy treatment, reducing the need for complementary sedative drugs. Chinese traditional medicine is promising as regards its role in stone prevention. An effort must be made in order to standardize study protocols to better assess acupuncture results since each procedure differs in regards to selected acupoints, electrostimulation technique and adjunct anesthetics. Similarly, standardization of Kampo formulations and acceptable clinical endpoints (imaging vs. symptomatic events) is needed.

How to improve results with extracorporeal shock wave lithotripsy

Shock wave lithotripsy (SWL) has greatly revolutionized the treatment of patients suffering from stone disease. There are a number of patient- and device-specific factors that can affect treatment outcome. Herein, we review practices that can increase the likelihood of SWL treatment success. A systematic literature review was performed to identify studies of SWL treatment parameters. Among the factors affecting the outcome of SWL were patient selection criteria, such as stone burden, stone location, and anatomic features. Additionally, technical aspects of the SWL procedure also can affect outcome; these factors include the acoustic output of the lithotripter, the coupling of the lithotripter to the patient, and the power, total number, and rate of shock wave delivery. The outcome of SWL can be optimized with close attention to patient selection criteria as well as the manner in which the treatment is performed.

Low-energy shock wave pretreatment results in greater vasoconstriction and less injury in the kidney compared to high-energy shock wave lithotripsy treatment alone.

Pretreating the kidney with low-energy shock waves (SWs) before administering a clinical dose of high-energy SWs has been found to greatly decrease the hemorrhagic lesion that normally results from high-energy shock wave lithotripsy (SWL) treatment alone. We tested the hypothesis that this novel pretreatment SWL protocol results in a greater and/or earlier renal vasoconstriction than clinical SWL alone, which could potentially explain the reduced bleeding in the kidney. Anesthetized pigs were treated with a clinical dose of SWs (2000 SWs, 24 kV, 120 SWs/min) or the pretreatment protocol (500 SWs, 12 kV, 120 SWs/min + 3-min pause + 2000 SWs, 24 kV, 120 SWs/min) using the HM3 lithotripter. Sonography (color and pulsed ultrasound) was used to locate a resistance artery within the SW-treated pole of the kidney and to take resistance index (RI) measurements from the blood vessel to estimate the resistance/impedance to blood flow. The results demonstrated that RI increased (renal vasoconstriction) earlier and greater during the pretreatment protocol compared to normal clinical SWL. Constricted blood vessels would likely be less prone to rupture by SWs and, if broken, would bleed less—resulting in a smaller hemorrhagic lesion.

Can infundibular height predict the clearance of lower pole calyceal stone after extracorporeal shockwave lithotripsy?

To evaluate the efficacy of extracorporeal shock wave lithotripsy (SWL) on lower calyceal calculi in relation to the renal anatomical factors and determine which of these factors can be used to select patients who will benefit from SWL. We analyzed retrospectively 78 patients with single radiopaque lower calyceal stones treated with SWL. The patients were evaluated 3 months after lithotripsy with a simple abdominal X-ray and a kidney ultrasound scan. The success of the treatment, removal of all fragments, was correlated with renal anatomical factors measured in the pre-treatment intravenous urography: infundibulopelvic angle, lower infundibulum width, lower infundibulum length, ratio length/width, infundibulum height, and number of minor calyces in the lower calyceal group. Three months after SWL treatment, 39 patients were stone-free (NR group) and 39 had residual fragments (R group). Both groups presented no differences in relation to infundibulopelvic angle, width and length of the lower calyceal infundibulum, length/width ratio of the lower infundibulum or number of lower calyces. Height of the infundibulum, described as the distance between the line passing through the lowest part of the calyx containing the calculus and the highest point of the lower lip of renal pelvis, was the only parameter in which significant differences (p = 0.002) were found between the NR and R groups. Lower Infundibular height could be a good measurement tool for deciding which patients with lower calyceal lithiasis would benefit from SWL treatment. Height of less than 22 mm suggests a good outcome from lithotripsy.

Shock wave lithotripsy treatment at 60 shock waves per minute is an appropriate protocol to minimize tissue injury.

Previous work has shown that the size of the renal hemorrhagic lesion caused by extracorporeal shock wave lithotripsy (SWL) is greatly reduced when shock waves (SWs) are delivered at 30 SWs/min instead of at the more commonly used rate of 120 SWs/min (0.08±0.02% versus 3.93±1.29% of functional renal volume, P=0.006). However, slowing the SW rate to 30 SWs/min greatly increases treatment time. Consequently, we investigated whether an intermediate rate of 60 SWs/min also reduces lesion size compared to treatment at 120 SWs/min. Methods: one kidney in 12 juvenile pigs was treated at 120 SWs/min (n=7) or at 60 SWs/min (n=5) with an unmodified Dornier HM-3 lithotripter (2000 SWs, 24 kV). After lithotripsy, the treated kidneys were fixed and removed to determine lesion size. Results: SWL at 60 SWs/min significantly reduced the size of the morphological lesion compared to 120 SWs/min (0.42±0.23% versus 3.93±1.29%, P=0.034). This reduction in lesion size was comparable to the lesion produced at 30 SWs/min. Conclusions: SWL applied at 60 SWs/min produces significantly less renal injury than SWL at 120 SWs/min, and produces an equivalent level of injury as that seen at 30 SWs/min.

Combination of Lower Pole Anatomic Features in A Single Infundibulopelvic Index Can Predict the Lower Pole Stone Clearance More Accurately

Purpose To investigate whether the combination of lower pole pelvicaliceal anatomic features in a single index can predict the outcome of shock wave lithotripsy treatment (SWL) of lower caliceal stones in children more accurately in stead of considering every single anatomic feature alone. Material and Methods The clinical records of children with lower caliceal stones who underwent SWL between 2002-2008 were reviewed. After excluding patients with ureteropelvic obstruction, major renal anatomic abnormalities, non-calcium stones, metabolic abnormalities, history of recurrent stone disease, multiple stones and previous renal surgery;25 paediatric patients were enrolled into study. Lower pole infundibulopelvic angle (IPA), infundibular length (IL) and width (IW) were measured from intravenous pyelography. Also, paediatric infundibulopelvic index(IPI) was calculated as [IPA( 0 )xIW(mm)x100]/[IL(mm)xstone size(mm 2 )xPelvicaliceal volume(mm 3 )]. Results The mean stone size was 72,4±49,4 mm 2 . Overall stone-free rate was %80.There were no statistically significant difference in IPA, IL and IW values between patients with residual stones and stone-free patients, respectively (p=0.06,p=0.81,p=0.21). Also no statistically significant difference were found in stone size (p=0.27),total pelvicaliceal volume(p=0.06) and SWL parameters. However IPI index was significantly different between two patient groups (p=0.04). Stone Free (mean±SD) Residual(mean±SD) P value Lower IPA( 0 ) 46,8±15,2 40±7,6 0,06 Lower IL 7,9±4 6,8±2 0,81 Lower IW 4,9±2,6 5,4±1,3 0,21 Lower IP index 0,14±0,18 0,028±0,019 0,04 Stone size 66,2±44,1 96,2±67,1 0,27 Mean number of session 1,6±0,8 1,6±0,58 0,87 Mean energy 16,9±1,2 18,3±1,1 0,06 Mean number of shockwave 2457,5±551,6 2785±786 0,33 Total pelvic volume of stone bearing kidney(range) 2621,2(582-7037) 1850(1505-17138) 0,07 Conclusions Results of this study let us think that although every single anatomic variation might have some effect on the SWL outcome of lower caliceal stones in paediatric patient basis, combination of all these anatomic parameters with the stone size in a single index could be a more accurate predictive tool because every single anatomic feature was a part of whole.

DO LITHOTRIPTORS MAINTAIN THEIR EFFECTIVENESS OVER TIME?

This study compared the efficacy and safety profile of electrohydraulic (EH) and electromagnetic (EM) lithotriptors in the treatment of 10- to 20-mm renal and proximal ureteric stones at a single center and by a single operator.Between January 2001 and December 2006, we sequentially treated patients meeting study inclusion criteria with MPL 9000 Dornier EH for the first 3 years, followed by the EM Siemens Modularis shockwave lithotripsy (SWL) unit. A single operator performed all SWL treatments under the supervision of an admitting urologist. We analyzed the demographic features and stone- and treatment-related parameters including complications for both groups. In each group, the stone-free rate and efficiency quotient was determined at 1-3 months.Of 274 patients, we sequentially treated 112 using the EH lithotriptor, and 162 the EM lithotriptor. The pre-SWL patients and stone-related parameters were similar in the two groups, except for diagnostic imaging modalities. The mean number of SWL sessions, need for ancillary procedure, retreatment rate, stone location, stone-free rate, and efficiency quotient were not significantly different between groups. The mean number of shockwaves required for complete fragmentation was 2977 and 6044 (P < .000) for the EH and EM groups, respectively.Single center, single operator experience with two types of lithotriptor indicated that both are equally efficacious, with similar safety profiles. The only significant difference was that the EH lithotriptor required fewer shockwaves for fragmentation.

Comparison of the effectiveness and safety of MPL 9000 and Lithostar Modularis shockwave lithotriptors: treatment results of 263 children

In this study, we aimed to compare the treatment results of two different shock wave lithotripsy (SWL) machines used in the management of pediatric urolithiasis. Between January 1993 and October 2004, Dornier MPL 9000 (electrohydraulic) had been used, and since then Siemens Lithostar Modularis (electromagnetic) has been used. The last evaluation was done 3 months after SWL treatment in terms of the success rate, use of anesthesia and complications. A total of 263 children (171 boys and 92 girls), with an age range of 9 months-14 years (mean age 8.1 +/- 3.8 years) were included in this study. Of the patients treated with the Dornier MPL 9000, 60.1% (173/104) required general anesthesia and 69 needed sedation. In contrast, for all patients treated with the Lithostar Modularis necessitated only sedo-analgesia (90 children). The hospital stay was shorter for Siemens Lithostar Modularis than those of Dornier MPL 9000 (26.2 vs. 35.5 h, P = 0.03). The success rate for the electromagnetic unit (86.5%) was almost identical that achieved with the electrohydraulic unit (85.2%) in the stones for the different location. Success rates were compared for stone burden subsets, the differences were insignificant for both lithotriptors (P > 0.05, for all). The electromagnetic unit had a significantly higher success rate for distal ureteral calculi (86.2 vs. 54.5%, P = 0.034). The efficiency quotients (EQ) for distal ureteral calculi were significantly different in favor of electromagnetic machine (56 vs. 40%). The complication rates for SWL were not significantly different for electrohydraulic and electromagnetic lithotriptors (8.7 and 6.2%, respectively). This study showed that SWL treatment was effective and safe in pediatric urolithiasis using both electrohydraulic and electromagnetic machines. Electromagnetic machine was more effective than electrohydraulic one for distal ureteral calculi. Additionally, the electromagnetic lithotriptor has significant clinical advantages over the electrohydraulic lithotriptor in terms of anesthesia requirements, hospitalization duration and fluoroscopic targeting.

The effect of age on outcomes in patients undergoing treatment for renal stones

Standard guidelines in management of urolithiasis might not be applicable to patients of extreme ages, namely children and the elderly population. This review summarizes the latest evidence on the effects of age on the outcomes, both treatment results and complications, in various treatment modalities for stone disease. Although age has been recently reported to be a significant negative predictor in elderly patients with renal stones receiving shock wave lithotripsy (SWL) treatment, there is increasing evidence suggesting SWL is well tolerated in children. For percutaneous nephrolithotomy and ureteroscopy, literature has shown that the outcomes in both age groups are similar to normal adult patients. Age does affect treatment outcome in patients with urinary stones. With the advance in endoscopy design and experience, percutaneous nephrolithotomy and ureteroscopy in these two extremes of age seem to be providing the same efficacy and safety as the standard adult population. However, for SWL, more precautions are to be taken for pediatric patients. For elderly patients, SWL may actually have a less satisfactory result than the other treatment modalities.

Ovarian apoptosis after shock wave lithotripsy for distal ureteral stones

The objective of this study is to identify any apoptotic effect of shock wave lithotripsy (SWL) for distal ureteral stones on ovarian tissue. Twenty-one female New Zealand White rabbits were divided into three groups of seven rabbits each: I (control), and II, III (treated and killed 14 and 28 days after SWL, respectively). The left distal ureteral segment of the anesthetized (ketamine HCl, 20 mg/kg) animals in groups II and III was exposed to 1,500 shock waves at 17 kV. Localization of the distal ureteral segments was achieved following contrast medium (Iohexol 300 mg of I/ml) injection. The animals were killed on day 14 or 28 after SWL, and the ovaries were removed. The follicle number with apoptotic changes in ovarian tissue was compared with control group. Apoptotic changes were determined by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) method. No increased apoptosis was detected in all groups. The mean number of TUNEL-positive follicle in groups I, II and III was 9.3 +/- 2.9, 8.1 +/- 2.6 and 8.7 +/- 2.9, respectively. There were no statistically significant differences among all groups regarding the number of TUNEL-positive follicle (P = 0.647). Also, no histomorphological change other than apoptosis was detected in the study groups. In conclusion, SWL treatment for distal ureteral stones does not induce apoptotic changes on ovarian tissue.

Does the Type of Lithotripter Affect Outcomes in Children with Upper Tract Urolithiasis?

To compare the treatment outcome and short-term safety of electrohydraulic and electromagnetic lithotripters in children. Comparative analysis of children undergoing shockwave lithotripsy (SWL) with a Dornier MPL 9000 electrohydraulic lithotripter (EHL) and a Siemens Modularis electromagnetic lithotripter (EML) was performed. All SWL treatments were performed by a single operator under the supervision of an admitting urologist. The demographic features, stone, and treatment-related parameters, including complications, were analyzed for both groups. Stone-free (SF) rates, re-treatment rate, and efficiency quotient (EQ) were calculated and compared for the two groups. Ninety-eight children had SWL for renal and proximal ureteral stones. There were 58 children in the EHL group and 40 in the EML group. There were no statistically significant differences between the groups in terms of age, sex, type of anesthesia, diagnostic modality, site, side, and size of the stones. Number of shockwaves used with EML was greater than with EHL (P < 0.00). SF rate was 95% and 77% for EHL and EML, respectively, with a statistically significant difference (P < 0.00). The re-treatment rate was equal in either group. The complication rate was higher with the EHL compared with the EML, although it did not reach statistical significance. Steinstrasse was the most common complication noted. EQ was 66% for the EHL, in comparison with 53% for the EML. The EHL has a better SF and EQ than the EML; however, short-term safety is marginally better with the EML.

Percutaneous nephrolithotomy for the treatment of lower pole renal calculi

Percutaneous nephrolithotomy for the treatment of lower pole renal calculi

Extracorporeal Shock Wave Lithotripsy in an Elderly Population: How to Prevent Complications and Make the Treatment Safe and Effective

The aim of our study is to consider the feasibility and the results of shock wave lithotripsy (SWL) in an elderly cohort of patients, considering different diseases and concomitant morbidity. From January 2003 up to July 2006, a total of 1100 SWL treatments were performed in our Stone Centre with Dornier Lithotripter S device. We retrospectively analyzed all the treatments carried out in patients older than 70 years of age, collecting a total of 130 patients. The average age was 75.1 years (range: 70-89). Stone location was renal in 95 and ureteral in 45 patients. Information about SWL outcomes and complications were collected as well as patient's characteristics and treatment modalities. Average stone size was 10.2+/-3.4 and 8.7+/-3.1 for the renal and ureteral location, respectively. 73 out of 140 patients (52.1%) were stone free after a single treatment; 49 patients (35%) required an adjunctive session, whereas SWL was unsuccessful in 18 (12.8%) patients. We observed 64, 24, 21, 10, 31 cases of concomitant arterial hypertension, diabetes mellitus, chronic renal failure, solitary kidney condition and previous neoplastic pathologies. A total of 8 and 6 subjects had previous cardiac surgery and atrial fibrillation respectively, thus requiring a warfarin scheduled conversion to low molecular weight heparin. Five patients had a pace maker implant and three patients an abdominal aortic aneurism. No SWL-related complications were found in this series considering both urological and systemic features. SWL represents the treatment of choice for urolithiasis, and it has to be recommended especially to geriatric patients. In those subjects, SWL complications can be avoided with a proper and personalized preparation, together with an ECG and ultrasound continuously monitored procedure.

Single Center, Single Operator Comparative Study of the Effectiveness of Electrohydraulic and Electromagnetic Lithotripters in the Management of 10- to 20-mm Single Upper Urinary Tract Calculi

This study compared the efficacy and safety profile of electrohydraulic (EH) and electromagnetic (EM) lithotriptors in the treatment of 10- to 20-mm renal and proximal ureteric stones at a single center and by a single operator. Between January 2001 and December 2006, we sequentially treated patients meeting study inclusion criteria with MPL 9000 Dornier EH for the first 3 years, followed by the EM Siemens Modularis shockwave lithotripsy (SWL) unit. A single operator performed all SWL treatments under the supervision of an admitting urologist. We analyzed the demographic features and stone- and treatment-related parameters including complications for both groups. In each group, the stone-free rate and efficiency quotient was determined at 1-3 months. Of 274 patients, we sequentially treated 112 using the EH lithotriptor, and 162 the EM lithotriptor. The pre-SWL patients and stone-related parameters were similar in the two groups, except for diagnostic imaging modalities. The mean number of SWL sessions, need for ancillary procedure, retreatment rate, stone location, stone-free rate, and efficiency quotient were not significantly different between groups. The mean number of shockwaves required for complete fragmentation was 2977 and 6044 (P < .000) for the EH and EM groups, respectively. Single center, single operator experience with two types of lithotriptor indicated that both are equally efficacious, with similar safety profiles. The only significant difference was that the EH lithotriptor required fewer shockwaves for fragmentation.

Stone Attenuation and Skin-to-Stone Distance on Computed Tomography Predicts for Stone Fragmentation by Shock Wave Lithotripsy

To determine whether stone attenuation and the skin-to-stone distance (SSD) can predict for stone fragmentation by SWL independently. Identifying the factors predictive of shock wave lithotripsy (SWL) outcome would help streamline the care of patients with stones. A retrospective review was performed of 111 patients undergoing initial SWL for a solitary, 5-20 mm, renal calculus. Stone size, location, attenuation value, and SSD were determined on pretreatment noncontrast computed tomography. The outcome was categorized as stone free, complete fragmentation <5 mm, and incomplete fragmentation >or=5 mm or unchanged at 2 weeks on kidney/ureter/bladder radiography. After SWL, 44 (40%) were stone free, 27 (24%) had complete fragmentation, and 40 (36%) of 111 patients had incomplete fragmentation. The stone attenuation of the successfully treated patients (stone free and complete fragmentation groups) was 837 +/- 277 Hounsfield units (HU) vs 1092 +/- 254 HU for those with treatment failure (incomplete fragmentation; P < .01). The mean SSD also differed: 9.6 cm +/- 2.0 vs 11.1 cm +/- 2.5 for the successful treatment group vs the treatment failure group, respectively (P = .01). On multivariate analysis, the factors that independently predicted the outcome were stone attenuation, SSD, and stone composition. When patients were stratified into 4 risk groups (stone <900 HU and SSD <9.0 cm, stone <900 HU and SSD >or=9.0 cm, stone >or=900 HU and SSD <9.0 cm, and stone >or=900 HU and SSD >or=9.0 cm), the SWL success rate was 91%, 79%, 58%, and 41%, respectively (odds ratio 7.1, 95% confidence interval 1.6-32 for <900 HU and SSD <9.0 cm group vs other 3 risk groups; P = .01). The results of our study have shown that a stone attenuation of <900 HU, SSD of <9 cm, and stone composition predict for SWL success, independent of stone size, location, and body mass index. These factors will be considered important in the prospective design of a SWL treatment nomogram at our center.

Does the rate of shock wave delivery affect outcomes in patients receiving shock wave lithotripsy for urinary calculi?

This Practice Point discusses a meta-analysis performed by Semins and colleagues, which included a total of 589 patients from four studies who were randomized to receive shock wave lithotripsy (SWL) delivered at either 120 shock waves per minute (fast rate) or 60 shock waves per minute (slow rate). The slow-rate group had a 10.2% increased chance of successful treatment compared with the fast-rate group (P = 0.002). Whilst this paper adds to existing evidence suggesting improved outcomes for slow-rate versus fast-rate SWL, the small sample size and heterogeneity of the studies included make it difficult to draw definitive conclusions. Varying the shock wave delivery rate according to patient, lithotripter system and stone characteristics, might form an important part of individualizing SWL treatment protocols. The potential advantages of slow-rate SWL must be weighed against the disadvantages of increased treatment times. Large multicenter studies will be required to determine how best to tailor SWL treatment to the individual patient.