New onset hypertension after extracorporeal shock wave lithotripsy: age related incidence and prediction by intrarenal resistive index

Effects of stone density on alteration in renal resistive index after extracorporeal shock wave lithotripsy for non-obstructed kidney stones

Aim The doppler-based renal resistive index is a recently proposed technique for measuring changes in renal perfusion and predicting acute kidney damage. The purpose of this study was to look at the influence of stone density on the renal resistive index (RI) after extracorporeal shock wave lithotripsy (ESWL) in patients with non-obstructed kidney stones. Material and Method Between May 2020 and July 2021, 48 consecutive patients with unilateral renal calculi of  20 mm were treated with ESWL monotherapy. The patients' non-contrast computed tomography (NCCT) images were processed and grouped into two groups using Hounsfield units (HU) (Group 1, n=27,  1000 HU; Group 2, n=21,  1000 HU). The same radiologist performed Doppler ultrasonography on all cases before, one hour, and one week following ESWL. Measurement of the RI taken in the remote region (at least 20 mm from the stones). Patient age, gender, BMI, stone laterality, stone size, and stone position were investigated as potential predictors. Results The average stone size for Group 1 was 11.7 ± 3.3 mm and 12.1 ± 2.8 mm for Group 2. The mean RI values before ESWL for Group 1 and Group 2 were 0.54 and 0.53, respectively. On comparing the pre-treatment data with the 1 hour after SWL, a statistically significant increase was recorded in the RI value for both groups. However, there was no significant difference in RI values between groups 1 and 2 1 hour and 1 week following lithotripsy therapy. After one week, the mean RI returned to pretreatment levels, according to a follow-up doppler investigation. There was no association between stone density and RI (p > 0.05). Conclusion Stone density is a significant independent predictor of ESWL outcome; however, high stone densities detected with NCCT were not associated with a significant change in RI. Post-ESWL therapy alterations are present and reversible one week after the treatment.

The Outcomes of Extracorporeal Shock Wave Lithotripsy for High-Density Renal Stone on Non-Contrast Computed Tomography

Introduction Urinary lithiasis is usually managed by extracorporeal shock wave lithotripsy (ESWL). Patients are examined using non-contrast computed tomography (NCCT) in order to evaluate the feasibility of ESWL, according to where the stone is located and how big is its size. The objective of this study is to determine the outcomes of ESWL in patients having high-density renal stone, evaluated using NCCT. Materials and methods A descriptive case series study was conducted in the Department of Urology, Sindh Institute of Urology & Transplantation, Karachi for six months. Patients of either gender aged between 25-50 years, who presented with solitary renal and ureteric calculi of 0.5-2 cm in diameter and high-density renal stones [>750 hounsfield units (HU)] were enrolled. ESWL was performed and a satisfactory outcome was defined as complete stone clearance in less than or equal to three ESWL sessions. Statistical Package for Social Sciences (SPSS) (IBM Corp., Armonk, NY) was used to analyze frequencies and percentages of the number of ESWL sessions, complete renal stone clearances, and satisfactory outcomes at the end of 12 weeks. A p-value of <0.05 was considered significant. Results The mean age of the patient was reported to be 34.08 ± 9.53 years. 51.6% male preponderance was noticed. Renal and ureteric stones were found in 69.7% and 30.3% of patients, respectively. 21.3% of patients showed stone clearance after two ESWL sessions, 27% of patients after three ESWL sessions, and 51.6% of patients after four ESWL sessions. Stone clearance was found in 58.2% of patients and a satisfactory outcome was found in 42.6% of patients. Conclusions Our results signify a satisfactory outcome of extracorporeal shock wave lithotripsy for high-density renal stone on non-contrast computed tomography. Further studies on a larger scale are needed to validate these results.

Extracorporeal Shockwave Lithotripsy Could Lead to a Prolonged Increase in the Renal Fibrotic Process of Up to 2 Years

INTRODUCTION AND OBJECTIVE

This prospective study aimed to evaluate the effect of ramping and pause protocols on renal fibrosis, blood pressure control, and renal function in patients receiving extracorporeal shockwave lithotripsy (SWL).

PATIENTS AND METHODS

This study prospectively recruited 320 patients with solitary radiopaque renal stones <15 mm in size. Patients were randomized to receive one of four shockwave protocols: (1) standard protocol (no ramping or pause); (2) ramping protocol alone; (3) ramping and pause protocols; or (4) pause protocol alone. Spot urine samples were collected before and for 2 years after treatment to monitor the levels of the renal fibrosis marker procollagen III aminoterminal propeptide (PIIINP) by blinded research staffs. Blood pressure and serum creatinine levels were also monitored during follow-up.

RESULTS

The four groups had comparable baseline data and treatment parameters. Significant increases (p < 0.05) in the urinary PIIINP levels from 6 weeks until 18 months after SWL were observed among all patients and in individual groups. PIIINP levels peaked at 1 year after SWL and gradually decreased to the baseline at 2 years. At the 2-year follow-up point, the overall serum creatinine levels remained significantly elevated (76.21-80.01 μmol/L, p < 0.001). Twenty (9.95%) patients developed new-onset hypertension and another 43 (36.4%) experienced worsening blood pressure control. However, no differences were observed among the four treatment groups.

CONCLUSIONS

SWL led to significant increases in renal fibrosis marker levels for up to 18 months after treatment. However, no differences in changes in renal fibrosis marker and serum creatinine levels and worsening of blood pressure control were observed with respect to the use of either ramping or pause treatment protocols.

Tracking kidney stones in a homogeneous medium using a trilateration approach

Shock wave lithotripsy is a non-invasive procedure by which kidney stones are fragmented by thousands of shock waves. Currently, many shock waves are delivered to the body that do not impact the stone, but do result in tissue trauma. This motivates developing a monitoring system to locate kidney stones, with the goal of gating shock waves not aligned with the stone, and hence, reducing renal trauma during lithotripsy. The system consists of a circular array housing twenty-two 0.5 MHz transducers that can be mounted on a clinical lithotripter. It was deployed in a water tank and tested with two stone models made from gypsum cement and a stone model fragment. An algorithm consisting of threshold detection, automatic rejection of weak signals, and triangulation was developed to determine the location of stones. The results show that within ±15 mm of the focus of the lithotripter, the accuracy was better than 4 mm in the lateral directions and 2 mm in the axial direction. Using off-the-shelf hardware, the algorithm can calculate stone positions every 1 s allowing for real-time tracking during lithotripsy.

Evaluation of selected Doppler parameters of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy

Introduction

Despite the risk of complications, which does not exceed several percent, extracorporeal shock wave lithotripsy (ESWL) causes morphological and functional changes in kidneys as a result of the effect of the generated shock wave energy on the renal parenchyma structure.

Material and methods

Forty-two patients were included in the study. The mean age in the studied group was 50.9 years (SD ±13.7). Extracorporeal lithotripsy treatments were carried out during the period from January 2014 to April 2014 using an electromagnetic shock wave generator. The spectrum of blood flow of the interlobar arteries of both the treated and the opposite kidney was investigated. On the basis of these spectrums, parameters such as: resistive index (RI), pulsatility index (PI) and acceleration time (AT) were calculated.

Results

The ESWL treatment causes a statistically significant increase of the RI parameter in the ipsilateral kidney (p <0.0001) as well as in the opposite kidney (p <0.0001). The RI value decreases after 92 hours after the treatment, reaching statistical significance in both kidneys (p <0.005). The PI parameter substantially increases after treatment in both kidneys (p <0.0001), and decreases after 92 hours (p <0.0001). Statistically significant correlations are shown between RI as well as the PI parameters and the patient's age.

Conclusions

Extracorporeal shock wave lithotripsy (ESWL) of renal stones causes temporary impairment of the renal perfusion in both ipsilateral and contralateral kidneys. The main factor that determines the value of the RI and PI parameters is the patient's age.

Electromagnetic and Electrohydraulic Shock Wave Lithotripsy-Induced Urothelial Damage: Is There a Difference?

PURPOSE

To evaluate and compare the acute effect of electromagnetic and electrohydraulic extracorporeal shockwave lithotripsy (SWL) on the urothelial layers of kidney and ureter.

MATERIALS AND METHODS

Fifty patients, 29 males (58%) and 21 females (42%), with an average age of 51.68 years (range: 37-70) who underwent SWL application in two different centers were included. Twenty-eight patients (56%) were treated with electrohydraulic and 22 (44%) were treated with electromagnetic lithotripsy. Urinary cytologic examinations were done immediately before and after SWL therapy and 10 days later. The average numbers of epithelial cells, red blood cells (RBC), and myocytes were counted under 40 × magnification.

RESULTS

There were significant differences in the number of epithelial cells and RBC before and after immediate application of SWL: 1.66 and 14.9 cells/field, (p = 0.001), 5.44 and 113.45 cells/field, respectively (p = 0.001). The number of RBC was significantly higher in patients treated with electromagnetic lithotripsy than those treated with electrohydraulic: 141.9 and 93.4 cells/field, respectively (p = 0.02). No myocyte or basement membrane elements were detected in any of the cytologic examinations. Cytologic examinations done after 10 days of SWL therapy revealed recovery of all abnormal cytologic findings.

CONCLUSIONS

The acute increments in the number of epithelial cells and RBC after SWL were statistically significant but it was not permanent. SWL-induced urinary urothelial lesion is limited to the mucosal layer and there was no evidence of damage to the basal membrane or muscle layer. Electromagnetic lithotripsy caused high numbers of RBC than the electrohydraulic device on the postimmediate urine cytologic examination.

Prevalence of diabetes mellitus after extra corporeal shock wave lithotripsy in 15 years follow-up

Objective:

To investigate the hypothesis that extracorporeal shock wave lithotripsy (ESWL) increases the risk of new onset diabetes mellitus (DM) or significant changes in fasting blood sugar (FBS).

Materials and Methods:

A total number of 307 patients enrolled in this study. All of them had undergone ESWL for kidney stone from 1991 to 1994. In 2009, after 15-19 years, we invited patients to check their blood sugar.

Results:

There were 307 patients, 19.8% females, and 80.1% males. The mean age of the patients was 44 for females and 42 years for males. 47.5% had kidney stone in the left side, 42.9% in the right side and 9.4% bilateral. The mean FBS increasing was 11.86 g/dl. It was 14.54 g/dl for the right side, 8.57 g/dl for left and 16.24 g/dl for bilateral ESWL.

Discussions:

The increasing of FBS is more significant in shock wave intensities higher than 15.5 KV. And there wasn't any significant relationship between age, sex, body mass index (BMI) and total number of shock waves with increasing of FBS. ESWL treatment might associate with increasing FBS without any relation to age, sex and BMI.

The Risk of Chronic Kidney Disease Associated with Urolithiasis and its Urological Treatments: A Review

PURPOSE

Urolithiasis can impair kidney function. This literature review focuses on the risk of kidney impairment in stone formers, the specific conditions associated with this risk and the impact of urological surgery.

MATERIALS AND METHODS

The PubMed® and Embase® databases were searched for publications on urolithiasis, its treatment, and the risk of chronic kidney disease, end stage renal disease and nephrectomy in stone formers.

RESULTS

In general, renal stone formers have twice the risk of chronic kidney disease or end stage renal disease, and for female and overweight stone formers the risk is even higher. Patients with frequent urinary tract infections, struvite stones, urinary malformations and diversions, malabsorptive bowel conditions and some monogenic disorders are at high risk for chronic kidney disease/end stage renal disease. Shock wave lithotripsy or minimally invasive urological interventions for stones do not adversely affect renal function. Declines in renal function generally occur in patients with preexisting chronic kidney disease or a large stone burden requiring repeated and/or complex surgery.

CONCLUSIONS

Although the effect size is modest, urolithiasis may cause chronic kidney disease and, thus, it is mandatory to assess patients with renal stones for the risk of chronic kidney disease/end stage renal disease. We suggest that all guidelines dealing with renal stone disease should include assessment of this risk.

Review on Lithotripsy and Cavitation in Urinary Stone Therapy

Cavitation is the sudden formation of vapor bubbles or voids in liquid media and occurs after rapid changes in pressure as a consequence of mechanical forces. It is mostly an undesirable phenomenon. Although the elimination of cavitation is a major topic in the study of fluid dynamics, its destructive nature could be exploited for therapeutic applications. Ultrasonic and hydrodynamic sources are two main origins for generating cavitation. The purpose of this review is to give the reader a general idea about the formation of cavitation phenomenon and existing biomedical applications of ultrasonic and hydrodynamic cavitation. Because of the high number of the studies on ultrasound cavitation in the literature, the main focus of this review is placed on the lithotripsy techniques, which have been widely used for the treatment of urinary stones. Accordingly, cavitation phenomenon and its basic concepts are presented in Section II. The significance of the ultrasound cavitation in the urinary stone treatment is discussed in Section III in detail and hydrodynamic cavitation as an important alternative for the ultrasound cavitation is included in Section IV. Finally, side effects of using both ultrasound and hydrodynamic cavitation in biomedical applications are presented in Section V.

Evaluation of long-term side effects after shock-wave lithotripsy for renal calculi using a third generation electromagnetic lithotripter

To assess the incidence of long-term side effects after shock-wave lithotripsy treatment performed with an electromagnetic Dornier Lithotripter S device. A specific follow-up was undertaken on a cohort of 100 selected patients that underwent SWL for a single renal stone in our center from 2002 to 2004. Previous and current data were compared using the Student t test. Factors associated with the incidence of hypertension and diabetes mellitus were determined. Ten years after treatment, mean serum creatinine level and glomerular filtration rate remained similar to previous values (serum creatinine level: 0.96 ± 0.22 vs. 0.92 ± 0.19 mg/dL; glomerular filtration rate: 92.8 ± 17.8 vs. 88.1 ± 21.7 mL/min). There were marked increases in blood cholesterol, blood pressure, and blood glucose levels, while smoking decreased. Age, glomerular filtration rate, body mass index, blood glucose and blood pressure at the time of treatment were significantly associated with the presence of hypertension and diabetes mellitus at follow-up; blood cholesterol was associated with diabetes mellitus development. After 10 years, overall renal function appeared to have been unaffected by shock-wave lithotripsy treatment. The increased rate of hypertension and diabetes mellitus were consistent with the incidence in the global population. This is the first report on the long-term safety of a third generation electromagnetic lithotripter, and indicates that there are no long-term sequelae.

Assessing the risk of incident hypertension and chronic kidney disease after exposure to shock wave lithotripsy and ureteroscopy

In this study we sought to determine if among individuals with urolithiasis, extracorporeal shock wave lithotripsy (SWL) and ureteroscopy are associated with a higher risk of incident arterial hypertension (HTN) and/or chronic kidney disease (CKD). This was measured in a population-based retrospective study of 11,570 participants with incident urolithiasis and 127,464 without urolithiasis in The Health Improvement Network. Patients with pre-existing HTN and CKD were excluded. The study included 1319 and 919 urolithiasis patients with at least one SWL or URS procedure, respectively. Multivariable Cox regression was used to estimate the hazard ratio for incident CKD stage 3-5 and HTN in separate analyses. Over a median of 3.7 and 4.1 years, 1423 and 595 of urolithiasis participants developed HTN and CKD, respectively. Urolithiasis was associated with a significant hazard ratio each for HTN of 1.42 (95% CI: 1.35, 1.51) and for CKD of 1.82 (1.67, 1.98). SWL was associated with a significant increased risk of HTN 1.34 (1.15, 1.57), while ureteroscopy was not. When further stratified as SWL to the kidney or ureter, only SWL to the kidney was significantly and independently associated with HTN 1.40 (1.19, 1.66). Neither SWL nor ureteroscopy was associated with incident CKD. Since urolithiasis itself was associated with a hazard ratio of 1.42 for HTN, an individual who undergoes SWL to the kidney can be expected to have a significantly increased hazard ratio for HTN of 1.96 (1.67, 2.29) compared with an individual without urolithiasis.

Renal Vasoconstriction Occurs Early During Shockwave Lithotripsy in Humans

INTRODUCTION

In animal models, pretreatment with low-energy shock waves and a pause decreased renal injury from shockwave lithotripsy (SWL). This is associated with an increase in perioperative renal resistive index (RI). A perioperative rise is not seen without the protective protocol, which suggests that renal vasoconstriction during SWL plays a role in protecting the kidney from injury. The purpose of our study was to investigate whether there is an increase in renal RI during SWL in humans.

MATERIALS AND METHODS

Subjects were prospectively recruited from two hospitals. All subjects received an initial 250 shocks at low setting, followed by a 2-minute pause. Treatment power was then increased. Measurements of the renal RI were taken before start of procedure, at 250, after 750, after 1500 shocks, and at the end of the procedure. A linear mixed-effects model was used to compare RIs at the different time points.

RESULTS

Fifteen patients were enrolled. Average treatment time was 46 ± 8 minutes. Average RI at pretreatment, after 250, after 750, after 1500 shocks, and post-treatment was 0.67 ± 0.06, 0.69 ± 0.08, 0.71 ± 0.07, 0.73 ± 0.07, and 0.74 ± 0.06, respectively. In adjusted analyses, RI was significantly increased after 750 shocks compared with pretreatment (p = 0.05).

CONCLUSION

Renal RI increases early during SWL in humans with the protective protocol. Monitoring for a rise in RI during SWL is feasible and may provide real-time feedback as to when the kidney is protected.

Is quantitative diffusion-weighted MRI a valuable technique for the detection of changes in kidneys after extracorporeal shock wave lithotripsy?

OBJECTIVE

The aim of this study was to evaluate the capability and the reliability of diffusion-weighted imaging (DWI) in the changes of kidneys occurring after extracorporeal shock wave lithotripsy (ESWL) treatment for renal stones.

MATERIALS AND METHODS

A total of 32 patients who underwent ESWL treatment for renal stone disease between June and December 2011 were enrolled in this prospective study. Color Doppler ultrasonography (CDUS) and DWI were performed before and within 24 hours after ESWL. DWI was obtained with b factors of 0, 500 and 1000 s/ mm2 at 1.5 T MRI. Each of Resistive index (RI) and ADC values were calculated from the three regions of renal upper, middle and lower zones for both of the affected and contralateral kidneys. Paired sample t test was used for statistical analyses.

RESULTS

After ESWL, the treated kidneys had statistically significant lower ADC values in all different regions compared with previous renal images. The best discriminative parameter was signal intensity with a b value of 1000 s/mm2. The changes of DWI after ESWL were noteworthy in the middle of the treated kidney (p < 0.01). There were no significant difference between RI values in all regions of treated and contralateral kidneys before and after treatment with ESWL (p>0.05).

CONCLUSION

DWI is a valuable technique enables the detection of changes in DWI after ESWL treatment that may provide useful information in prediction of renal damage by shock waves, even CDUS is normal.

Effect of renal shock wave lithotripsy on the development of metabolic syndrome in a juvenile swine model: a pilot study

PURPOSE

We performed a pilot study to assess whether renal shock wave lithotripsy influences metabolic syndrome onset and severity.

MATERIALS AND METHODS

Three-month-old juvenile female Ossabaw miniature pigs were treated with shock wave lithotripsy (2,000 shock waves at 24 kV with 120 shock waves per minute in 2) or sham shock wave lithotripsy (no shock waves in 2). Shock waves were targeted to the upper pole of the left kidney to model treatment that would also expose the pancreatic tail to shock waves. Pigs were then instrumented to directly measure arterial blood pressure via an implanted radiotelemetry device. They later received a hypercaloric atherogenic diet for about 7 months. Metabolic syndrome development was assessed by the intravenous glucose tolerance test.

RESULTS

Metabolic syndrome progression and severity were similar in the sham treated and lithotripsy groups. The only exception arterial blood pressure, which remained relatively constant in sham treated pigs but began to increase at about 2 months towards hypertensive levels in lithotripsy treated pigs. Metabolic data on the 2 groups were pooled to provide a more complete assessment of metabolic syndrome development and progression in this juvenile pig model. The intravenous glucose tolerance test revealed substantial insulin resistance with impaired glucose tolerance within 2 months on the hypercaloric atherogenic diet with signs of further metabolic impairment at 7 months.

CONCLUSIONS

These preliminary results suggest that renal shock wave lithotripsy is not a risk factor for worsening glucose tolerance or diabetes mellitus onset. However, it appears to be a risk factor for early onset hypertension in metabolic syndrome.

The protective role of coenzyme Q10 in renal injury associated with extracorporeal shockwave lithotripsy: a randomised, placebo-controlled clinical trial

OBJECTIVE

To determine the efficacy of coenzyme Q10 (CoQ10) in preventing renal injury in patients with lithiasis undergoing extracorporeal shockwave lithotripsy (ESWL).

PATIENTS AND METHODS

Prospective, randomised, double-blind, placebo-controlled clinical trial of 100 patients with renal lithiasis who were treated with ESWL. The patients were distributed randomly into two groups receiving either placebo or CoQ10 (200 mg/day), a powerful antioxidant with vasoactive properties, orally administered during the week before ESWL and for 1 week after. Renal dysfunction markers, vasoactive hormones, oxidative stress, plasma levels of several interleukins and vascular resistance index (VRI) using Doppler ultrasound were evaluated the week before ESWL, 2 h before ESWL and at 2 h, 24 h and 7 days after ESWL.

RESULTS

There was a significant increase in glomerular filtration (P = 0.013), as well as a decrease in the albumin/creatinine ratio and the β2 -microglobulin level (P = 0.02) after 1 week of treatment in the CoQ10 group. These changes were maintained at the follow-up after ESWL. The administration of CoQ10 was associated with improvement in vasoactive hormone parameters, VRI and interleukin levels. These improvements were maintained until the end of the follow-up period. However, the administration of CoQ10 was not associated with significant changes in the oxidative stress parameters.

CONCLUSION

Our results indicate that CoQ10 administration improves renal function and vasoactive and inflammation parameter values, allowing for preconditioning before the tissue insult caused by ESWL.

A systematic review and meta-analysis of new onset hypertension after extracorporeal shock wave lithotripsy

OBJECTIVE

Previous studies on the association between extracorporeal shock wave lithotripsy (SWL) and new onset hypertension have only illustrated contradictory results. In order to illustrate the association between SWL and new onset hypertension, a meta-analysis of case-control and cohort studies was conducted.

METHODS

Relevant literature was searched using PubMed, EMBASE, and the Cochrane Central Search Library. A meta-analysis of the association between SWL and new onset hypertension was performed. Studies were pooled, and summary relative risk was calculated. Subgroup analyses were also conducted.

RESULTS

Eleven studies were eligible for our analysis. No statistical significance was detected between SWL and new onset hypertension (RR = 1.06, 95 % CI 0.83-1.35). No association was observed when stratified analyses were performed on age, gender, study design, bilateral SWL, and different machines.

CONCLUSION

Our analysis indicated that no association was found between SWL and the development of hypertension.

Extracorporal shock wave lithotripsy in the management of stones in children with oxalosis--still the first choice?

BACKGROUND

Primary hyperoxaluria (PH) is a recognised cause of nephrolithiasis. The aim of this study was to evaluate the success of extracorporal shock wave lithotripsy (ESWL) in treating nephrolithiasis in children with PH.

METHODS

This was a retrospective review of patient characteristics, treatments and outcomes of 36 children with oxalate stones due to PH.

RESULTS

A total of 52 stones were formed in 28 patients, of which 23 stones were treated with ESWL. Of these 23 stones, ten improved and 13 did not; nine were located in the upper pole, nine in the lower pole and four and one in the pelvic and ureteric areas, respectively. All pelvic and ureteric stones improved, while 66.7 % of upper pole stones and 89.9 % of lower pole stones did not; 20 % of PH type 1 stones improved compared to 47 % of PH type 2 stones. The mean pre- and post-eGFR in stone-improvers was 98.82 and 104.7 ml/min/1.73 m(2), respectively; in the non-improvers, these values were 100.75 and 95.68 ml/min/1.73 m(2), respectively. Mean pre-ESWL stone size in the improved and non-improved groups was 7.3 mm and 8.5 mm respectively.

CONCLUSIONS

Based on our results, ESWL is not the ideal method of stone therapy for patients with PH. ESWL was more effective in treating pelvic and ureteric stones, with upper pole stone response being better than lower pole response. PH2 patients were more than twice as likely to respond to ESWL treatment. Stone size and prior preventive treatment did not affect outcome. eGFR was not affected by ESWL.

Optimising an escalating shockwave amplitude treatment strategy to protect the kidney from injury during shockwave lithotripsy

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Animal studies have shown that one approach to reduce SWL-induced renal injury is to pause treatment for 3-4 min early in the SWL-treatment protocol. However, there is typically no pause in treatment during clinical lithotripsy. We show in a porcine model that a pause in SWL treatment is unnecessary to achieve a reduction in renal injury if treatment is begun at a low power setting that generates low-amplitude SWs, and given continuously for ≈ 4 min before applying higher-amplitude SWs.

OBJECTIVE

• To test the idea that a pause (≈ 3 min) in the delivery of shockwaves (SWs) soon after the initiation of SW lithotripsy (SWL) is unnecessary for achieving a reduction in renal injury, if treatment is begun at a low power setting that generates low-amplitude SWs.

MATERIALS AND METHODS

• Anaesthetised female pigs were assigned to one of three SWL treatment protocols that did not involve a pause in SW delivery of >10 s (2000 SWs at 24 kV; 100 SWs at 12 kV + ≈ 10-s pause + 2000 SWs at 24 kV; 500 SWs at 12 kV + ≈ 10-s pause + 2000 SWs at 24 kV). • All SWs were delivered at 120 SWs/min using an unmodified Dornier HM3 lithotripter. • Renal function was measured before and after SWL. • The kidneys were then processed for quantification of the SWL-induced haemorrhagic lesion. Values for lesion size were compared to previous data collected from pigs in which treatment included a 3-min pause in SW delivery.

RESULTS

• All SWL treatment protocols produced a similar degree of vasoconstriction (23-41% reduction in glomerular filtration rate and effective renal plasma flow) in the SW-treated kidney. • The mean renal lesion in pigs treated with 100 low-amplitude SWs delivered before the main dose of 2000 high-amplitude SWs (2.27% functional renal volume [FRV]) was statistically similar to that measured for pigs treated with 2000 SWs all at high-amplitude (3.29% FRV). • However, pigs treated with 500 low-amplitude SWs before the main SW dose had a significantly smaller lesion (0.44% FRV) that was comparable with the lesion in pigs from a previous study in which there was a 3-min pause in treatment separating a smaller initial dose of 100 low-amplitude SWs from the main dose of 2000 high-amplitude SWs (0.46% FRV). The time between the initiation of the low - and high-amplitude SWs was ≈ 4 min for these latter two groups compared with ≈ 1 min when there was negligible pause after the initial 100 low-amplitude SWs in the protocol.

CONCLUSIONS

• Pig kidneys treated by SWL using a two-step low-to-high power ramping protocol were protected from injury with negligible pause between steps, provided the time between the initiation of low-amplitude SWs and switching to high-amplitude SWs was ≈ 4 min. • Comparison with results from previous studies shows that protection can be achieved using various step-wise treatment scenarios in which either the initial dose of SWs is delivered at low-amplitude for ≈ 4 min, or there is a definitive pause before resuming SW treatment at higher amplitude. • Thus, we conclude that renal protection can be achieved without instituting a pause in SWL treatment. It remains prudent to consider that renal protection depends on the acoustic and temporal properties of SWs administered at the beginning stages of a SWL ramping protocol, and that this may differ according to the lithotripter being used.

Overview of therapeutic ultrasound applications and safety considerations

Applications of ultrasound in medicine for therapeutic purposes have been accepted and beneficial uses of ultrasonic biological effects for many years. Low-power ultrasound of about 1 MHz has been widely applied since the 1950s for physical therapy in conditions such as tendinitis and bursitis. In the 1980s, high-pressure-amplitude shock waves came into use for mechanically resolving kidney stones, and "lithotripsy" rapidly replaced surgery as the most frequent treatment choice. The use of ultrasonic energy for therapy continues to expand, and approved applications now include uterine fibroid ablation, cataract removal (phacoemulsification), surgical tissue cutting and hemostasis, transdermal drug delivery, and bone fracture healing, among others. Undesirable bioeffects can occur, including burns from thermal-based therapies and severe hemorrhage from mechanical-based therapies (eg, lithotripsy). In all of these therapeutic applications of ultrasound bioeffects, standardization, ultrasound dosimetry, benefits assurance, and side-effect risk minimization must be carefully considered to ensure an optimal benefit to risk ratio for the patient. Therapeutic ultrasound typically has well-defined benefits and risks and therefore presents a manageable safety problem to the clinician. However, safety information can be scattered, confusing, or subject to commercial conflicts of interest. Of paramount importance for managing this problem is the communication of practical safety information by authoritative groups, such as the American Institute of Ultrasound in Medicine, to the medical ultrasound community. In this overview, the Bioeffects Committee of the American Institute of Ultrasound in Medicine outlines the wide range of therapeutic ultrasound methods, which are in clinical use or under study, and provides general guidance for ensuring therapeutic ultrasound safety.

Chronic kidney disease in kidney stone formers

Recent population studies have found symptomatic kidney stone formers to be at increased risk for chronic kidney disease (CKD). Although kidney stones are not commonly identified as the primary cause of ESRD, they still may be important contributing factors. Paradoxically, CKD can be protective against forming kidney stones because of the substantial reduction in urine calcium excretion. Among stone formers, those with rare hereditary diseases (cystinuria, primary hyperoxaluria, Dent disease, and 2,8 dihydroxyadenine stones), recurrent urinary tract infections, struvite stones, hypertension, and diabetes seem to be at highest risk for CKD. The primary mechanism for CKD from kidney stones is usually attributed to an obstructive uropathy or pyelonephritis, but crystal plugs at the ducts of Bellini and parenchymal injury from shockwave lithotripsy may also contribute. The historical shift to less invasive surgical management of kidney stones has likely had a beneficial impact on the risk for CKD. Among potential kidney donors, past symptomatic kidney stones but not radiographic stones found on computed tomography scans were associated with albuminuria. Kidney stones detected by ultrasound screening have also been associated with CKD in the general population. Further studies that better classify CKD, better characterize stone formers, more thoroughly address potential confounding by comorbidities, and have active instead of passive follow-up to avoid detection bias are needed.

Pretreatment with low-energy shock waves reduces the renal oxidative stress and inflammation caused by high-energy shock wave lithotripsy

The purpose of this study was to determine if pretreatment of porcine kidneys with low-energy shock waves (SWs) prior to delivery of a clinical dose of 2,000 SWs reduces or prevents shock wave lithotripsy (SWL)-induced acute oxidative stress and inflammation in the treated kidney. Pigs (7-8 weeks old) received 2,000 SWs at 24 kV (120 SW/min) with or without pretreatment with 100 SWs at 12 kV/2 Hz to the lower pole calyx of one kidney using the HM3. Four hours post-treatment, selected samples of renal tissue were frozen for analysis of cytokine, interleukin-6 (IL-6), and stress response protein, heme oxygenase-1 (HO-1). Urine samples were taken before and after treatment for analysis of tumor necrosis factor-α (TNF-α). Treatment with 2,000 SWs with or without pretreatment caused a statistically significant elevation of HO-1 and IL-6 in the renal medulla localized to the focal zone of the lithotripter. However, the increase in HO-1 and IL-6 was significantly reduced using the pretreatment protocol compared to no pretreatment. Urinary excretion of TNF-α increased significantly (p < 0.05) from baseline for pigs receiving 2,000 SWs alone; however, this effect was completely abolished with the pretreatment protocol. We conclude that pretreatment of the kidney with a low dose of low-energy SWs prior to delivery of a clinical dose of SWs reduces, but does not completely prevent, SWL-induced acute renal oxidative stress and inflammation.

Effect of shock wave number on renal oxidative stress and inflammation

OBJECTIVE To determine if the magnitude of the acute injury response to shock-wave lithotripsy (SWL) depends on the number of SWs delivered to the kidney, as SWL causes acute renal oxidative stress and inflammation which are most severe in the portion of the kidney within the focal zone of the lithotripter. MATERIALS AND METHODS Pigs (7-8 weeks old) received 500, 1000 or 2000 SWs at 24 kV from a lithotripter to the lower pole calyx of one kidney. At 4 h after treatment the kidneys were removed, and samples of cortex and medulla were frozen for analysis of the cytokine, interleukin-6, and for the stress response protein, heme oxygenase-1 (HO-1). Urine samples taken before and after treatment were analysed for the inflammatory cytokine, tumour necrosis factor-α. For comparison, we included previously published cytokine data from pigs exposed to sham treatment. RESULTS Treatment with either 1000 or 2000 SWs caused a significant induction of HO-1 in the renal medulla within the focal zone of the lithotripter (F2, 1000 SWs, P < 0.05; 2000 SWs, P < 0.001). Interleukin-6 was also significantly elevated in the renal medulla of the pigs that received either 1000 or 2000 SWs (P < 0.05 and <0.001, respectively). Linear dose-response modelling showed a significant correlation between the HO-1 and interleukin-6 responses with SW dose (P < 0.001). Urinary excretion of tumour necrosis factor-α from the lithotripsy-treated kidney increased only for pigs that received 2000 SWs (P < 0.05). CONCLUSION The magnitude of renal oxidative stress and inflammatory response in the medulla increased with the number of SWs. However, it is not known if the HO-1 response is beneficial or deleterious; determining that will inform us whether SWL-induced renal injury can be assessed by quantifying markers of oxidative stress and inflammation.

Shock wave lithotripsy is not predictive of hypertension among community stone formers at long-term followup

PURPOSE

Concern exists over the subsequent development of hypertension after shock wave lithotripsy for the treatment of symptomatic urolithiasis. Referral bias and lack of long-term followup have been limitations of prior studies.

MATERIALS AND METHODS

We identified all Olmsted County, Minnesota residents with a diagnosis of urolithiasis from 1985 to 2008. The charts were electronically queried for hypertension and obesity by diagnostic codes, and use of shock wave lithotripsy by surgical codes. All patients first diagnosed with hypertension before or up to 90 days after the first documented kidney stone were considered to have prevalent hypertension and were excluded from analysis. Cox proportional hazards models were used to assess the association of shock wave lithotripsy with a subsequent diagnosis of hypertension.

RESULTS

We identified 6,077 patients with incident urolithiasis with more than 90 days of followup. We excluded 1,295 (21.3%) members of the population for prevalent hypertension leaving 4,782 patients with incident urolithiasis for analysis. During an average followup of 8.7 years new onset hypertension was diagnosed in 983 (20.6%) members of the cohort at a mean of 6.0 years from the index stone date. Only 400 (8.4%) patients in the cohort were treated with shock wave lithotripsy. There was no significant association between shock wave lithotripsy and the development of hypertension in univariate (p = 0.33) and multivariate modeling controlling for age, gender and obesity (HR 1.03; 95% CI 0.84, 1.27; p = 0.77).

CONCLUSIONS

In a large population based cohort of kidney stone formers we failed to identify an association between shock wave lithotripsy and the subsequent long-term risk of hypertension.

Urine cytology to evaluate urinary urothelial damage of shock-wave lithotripsy

Our aim is to study the prospective trial where urine cytology was used to detect the acute urothelial mucosal damage in patients who undergo extracorporeal shock waves lithotripsy (SWL). The study included 48 consecutive patients (28 male, 20 female) with mean age of 49.02 years (range 18-66) who were treated with SWL due to renal stones (30 patients) or upper ureter stones (18 patients). The mean calculi diameter was 12.44 mm (range 5-20). Urinary cytologic examinations were done for all patients immediately before and after SWL therapy and 10 days latter. The average numbers of transitional cells, red blood cells and myocytes were counted under 40 × magnification. In overall patients the average numbers of transitional cells at the cytologic examinations done immediately before and after SWL therapy were 1.6 and 7.53 cell/field, respectively (p = 0.001). The increment in transitional cells at cytologic examination after SWL was significantly influenced only by number of shock waves applied (p = 0.003). No muscle cell was detected in all cytologic examinations. The cytologic examinations which were done after 10 days of SWL therapy showed recovery from all cytologic abnormalities. The acute increment in number of transitional cells after the SWL is not clinically important and it is a temporary change. Urothelial lesion is limited to mucosal layer and there is no evidence of damage to basal membrane or deeper muscle layer. SWL safety on urothelial and muscular layer was demonstrated. However, evaluation of larger series with use of other lithotripters is necessary before reaching any definitive conclusions.

A chronic outcome of shock wave lithotripsy is parenchymal fibrosis

Shock wave lithotripsy (SWL) is widely viewed as an effective noninvasive method to break stones within the kidney and ureter. However, it is a technology that is not without trauma to the kidney--acute vascular, tubular and interstitial damage is often reported that if severe enough can lead to renal fibrosis (scarring) and permanent loss of functional parenchyma. These chronic changes can potentially lead to serious long-term adverse effects. The risk of developing chronic fibrotic lesions after lithotripsy is influenced by the number of shock waves (SWs) administered, SW power, rate of SW delivery and the number of SWL treatment sessions. The interplay between these risk factors is largely unknown, but progress has been made in identifying SWL protocols and pharmacologic therapies that can ameliorate the acute and chronic tissue damage that is an unintended consequence of SWL treatment.

Shock wave lithotripsy: advances in technology and technique

Shock wave lithotripsy (SWL) is the only noninvasive method for stone removal. Once considered as a primary option for the treatment of virtually all stones, SWL is now recognized to have important limitations that restrict its use. In particular, the effectiveness of SWL is severely limited by stone burden, and treatment with shock waves carries the risk of acute injury with the potential for long-term adverse effects. Research aiming to characterize the renal response to shock waves and to determine the mechanisms of shock wave action in stone breakage and renal injury has begun to suggest new treatment strategies to improve success rates and safety. Urologists can achieve better outcomes by treating at slower shock wave rate using a step-wise protocol. The aim is to achieve stone comminution using as few shock waves and at as low a power level as possible. Important challenges remain, including the need to improve acoustic coupling, enhance stone targeting, better determine when stone breakage is complete, and minimize the occurrence of residual stone fragments. New technologies have begun to address many of these issues, and hold considerable promise for the future.

Shock wave lithotripsy: a randomized, double-blind trial to compare immediate versus delayed voltage escalation

OBJECTIVES

To present a randomized trial investigating immediate vs delayed voltage escalation during shock wave lithotripsy (SWL). SWL efficiency is affected by the energy setting of the lithotripter, the consumption level of the electrode, and the rate of shock wave administration. Preliminary data have suggested that delaying voltage escalation for SWL might both improve fragmentation and minimize renal injury.

METHODS

A total of 160 patients with previously untreated radiopaque renal calculi were randomized to undergo immediate vs delayed voltage escalation SWL. Success was defined as an asymptomatic patient who was stone free or had adequate fragmentation (sand or fragments < or = 4 mm) at 3 months after treatment.

RESULTS

Of the 160 patients, 83 were treated with immediate voltage escalation SWL and 77 patients with delayed escalation. The groups were similar in sex, body mass index, stone area, and stone location. The overall success rate at 3 months was 72.5% for immediate vs 54.5% for delayed SWL (P = .021). After adjusting for body mass index, sex, and stone location, the stone area decreased more rapidly in patients treated with immediate voltage escalation (P = .002). A trend was also seen for immediate voltage escalation to be more effective in the treatment of smaller calculi with a cross-sectional area of < 100 mm(2) (P = .089) compared with calculi with a cross-sectional area of > or = 100 mm(2) (P = .248). No differences were seen in the complications or ancillary procedures between the 2 treatments (P = .667 and P = .355, respectively). No perinephric hematomas were observed in either group.

CONCLUSIONS

These results suggest that delayed voltage escalation might not provide superior stone fragmentation compared with conventional, immediate voltage escalation.

Lithotripsy

Shock wave lithotripsy (SWL) is the process of fragmentation of renal or ureteric stones by the use of repetitive shock waves generated outside the body and focused onto the stone. Following its introduction in 1980, SWL revolutionized the treatment of kidney stones by offering patients a non-invasive procedure. It is now seen as a mature technology and its use is perceived to be routine. It is noteworthy that, at the time of its introduction, there was a great effort to discover the mechanism(s) by which it works, and the type of sound field that is optimal. Although nearly three decades of subsequent research have increased the knowledge base significantly, the mechanisms are still controversial. Furthermore there is a growing body of evidence that SWL results in injury to the kidney which may have long-term side effects, such as new onset hypertension, although again there is much controversy within the field. Currently, use of lithotripsy is waning, particularly with the advent of minimally invasive ureteroscopic approaches. The goal here is to review the state of the art in SWL and to present the barriers and challenges that need to be addressed for SWL to deliver on its initial promise of a safe, effective, non-invasive treatment for kidney stones.

Extracorporeal shock wave lithotripsy at 60 shock waves/min reduces renal injury in a porcine model

OBJECTIVE

To determine if extracorporeal shock wave lithotripsy (ESWL) at 60 shock waves (SWs)/min reduces renal damage and haemodynamic impairment compared to treatment at 120 SWs/min.

MATERIALS AND METHODS

One kidney in each of 19 juvenile pigs (7-8 weeks old) was treated at 120 or at 60 SWs/min (2000 SWs, 24 kV) with an unmodified HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA). Renal function was determined before and after ESWL treatment by inulin clearance, extraction and clearance of para-aminohippuric acid. Both kidneys were then removed to measure parenchymal lesion size by sectioning the entire kidney and quantifying the size of the haemorrhagic lesion in each slice.

RESULTS

ESWL at 60 SWs/min significantly reduced the size of the acute morphological lesion compared to 120 SWs/min (0.42% vs 3.93% of functional renal volume, P = 0.011) and blunted the decrease in glomerular filtration rate and renal plasma flow normally seen after treatment at 120 SWs/min.

CONCLUSIONS

Treatment at a firing rate of 60 SWs/min produces less morphological injury and causes less alteration in renal haemodynamics than treatment at 120 SWs/min in the pig model of ESWL-induced renal injury.

Pretreatment with low-energy shock waves induces renal vasoconstriction during standard shock wave lithotripsy (SWL): a treatment protocol known to reduce SWL-induced renal injury

OBJECTIVE

To test the hypothesis that the pretreatment of the kidney with low-energy shock waves (SWs) will induce renal vasoconstriction sooner than a standard clinical dose of high-energy SWs, thus providing a potential mechanism by which the pretreatment SW lithotripsy (SWL) protocol reduces tissue injury.

MATERIALS AND METHODS

Female farm pigs (6-weeks-old) were anaesthetized with isoflurane and the lower pole of the right kidney treated with SWs using a conventional electrohydraulic lithotripter (HM3, Dornier GmbH, Germany). Pulsed Doppler ultrasonography was used to measure renal resistive index (RI) in blood vessels as a measure of resistance/impedance to blood flow. RI was recorded from one intralobar artery located in the targeted pole of the kidney, and measurements taken from pigs given sham SW treatment (Group 1; no SWs, four pigs), a standard clinical dose of high-energy SWs (Group 2; 2000 SWs, 24 kV, 120 SWs/min, seven pigs), low-energy SW pretreatment followed by high-energy SWL (Group 3; 500 SWs, 12 kV, 120 SWs/min + 2000 SWs, 24 kV, 120 SWs/min, eight pigs) and low-energy SW pretreatment alone (Group 4; 500 SWs, 12 kV, 120 SWs/min, six pigs).

RESULTS

Baseline RI (approximately 0.61) was similar for all groups. Pigs receiving sham SW treatment (Group 1) had no significant change in RI. A standard clinical dose of high-energy SWs (Group 2) did not significantly alter RI during treatment, but did increase RI at 45 min after SWL. Low-energy SWs did not alter RI in Group 3 pigs, but subsequent treatment with a standard clinical dose of high-energy SWs resulted in a significantly earlier (at 1000 SWs) and greater (two-fold) rise in RI than that in Group 2 pigs. This rise in RI during the low/high-energy SWL protocol was not due to a delayed vasoconstrictor response of pretreatment, as low-energy SW treatment alone (Group 4) did not increase RI until 65 min after SWL.

CONCLUSIONS

The pretreatment protocol induces renal vasoconstriction during the period of SW application whereas the standard protocol shows vasoconstriction occurring after SWL. Thus, the earlier and greater rise in RI during the pretreatment protocol may be causally associated with a reduction in tissue injury.

Assessment of renal injury with a clinical dual head lithotriptor delivering 240 shock waves per minute

PURPOSE

Lithotriptors with 2 treatment heads deliver shock waves along separate paths. Firing 1 head and then the other in alternating mode has been suggested as a strategy to treat stones twice as rapidly as with conventional shock wave lithotripsy. Because the shock wave rate is known to have a role in shock wave lithotripsy induced injury, and given that treatment using 2 separate shock wave sources exposes more renal tissue to shock wave energy than treatment with a conventional lithotriptor, we assessed renal trauma in pigs following treatment at rapid rate (240 shock waves per minute and 120 shock waves per minute per head) using a Duet lithotriptor (Direx Medical Systems, Petach Tikva, Israel) fired in alternating mode.

MATERIALS AND METHODS

Eight adult female pigs (Hardin Farms, Danville, Indiana) each were treated with sham shock wave lithotripsy or 2,400 shock waves delivered in alternating mode (1,200 shock waves per head, 120 shock waves per minute per head and 240 shock waves per minute overall at a power level of 10) to the lower renal pole. Renal functional parameters, including glomerular filtration rate and effective renal plasma flow, were determined before and 1 hour after shock wave lithotripsy. The kidneys were perfusion fixed in situ and the hemorrhagic lesion was quantified as a percent of functional renal volume.

RESULTS

Shock wave treatment resulted in no significant change in renal function and the response was similar to the functional response seen in sham shock wave treated animals. In 6 pigs treated with alternating mode the renal lesion was small at a mean +/- SEM of 0.22% +/- 0.09% of functional renal volume.

CONCLUSIONS

Kidney tissue and function were minimally affected by a clinical dose of shock waves delivered in alternating mode (120 shock waves per minute per head and 240 shock waves per minute overall) with a Duet lithotriptor. These observations decrease concern that dual head lithotripsy at a rapid rate is inherently dangerous.

Management options for lower pole renal calculi

PURPOSE OF REVIEW

The optimal treatment of lower pole renal calculi is controversial. Shock wave lithotripsy, ureteroscopy and percutaneous nephrostolithotomy all constitute viable therapeutic options in select patients.

RECENT FINDINGS

Lower pole stones smaller than 1 cm in diameter can be managed with observation, shock wave lithotripsy or ureteroscopy. Patients electing expectant management should be counseled regarding the potential for stone-related symptom progression and need for future intervention. Shock wave lithotripsy and ureteroscopy have similar stone-free rates, although shock wave lithotripsy may be preferable due to more favorable secondary outcomes. Lower pole stones 1-2 cm in diameter are best managed with percutaneous nephrostolithotomy, although ureteroscopy is an option in select patients, particularly those not considered candidates for percutaneous nephrostolithotomy. Finally, patients with lower pole stones larger than 2 cm are best served with percutaneous nephrostolithotomy, as the morbidity in experienced hands is low and stone-free rates are unequivocally higher than those of other treatment modalities.

SUMMARY

A variety of factors, including patient body habitus, local renal anatomy, cost and patient preference, must be taken into consideration when determining the optimal treatment modality for lower pole renal calculi.

Potential for cavitation-mediated tissue damage in shockwave lithotripsy

PURPOSE

Shockwave lithotripsy (SWL) injures renal tissue, and cavitation has been reported to mediate some of these effects. Much of the work characterizing the cavitation injury of SWL has been performed in small animals or in vitro. We describe experiments that promote cavitation during SWL and estimate the spatial distribution of the resulting hemorrhagic lesion in a large-animal (porcine) model of clinical lithotripsy.

MATERIALS AND METHODS

The lower pole calix of the left kidney in female farm pigs was targeted for SWL with a Dornier HM3 lithotripter. Intraventricular injections of polystyrene microspheres were made before and at intervals during lithotripsy to blanket systemic circulation with cavitation nuclei. Following SWL, the abdominal viscera were inspected and the kidneys were processed for morphologic analysis.

RESULTS

Extensive surface hemorrhage occurred over both the targeted and contralateral kidneys, along with widespread petechial hemorrhage over the spleen, intestines, and peritoneum. The targeted kidneys developed subcapsular hematomas. Histology revealed focal and diffuse damage to the targeted kidneys and vascular rupture in both kidneys with complete necrosis of the walls of intralobular arteries and veins.

CONCLUSIONS

These results demonstrate the potential for unfocused shockwaves to damage blood vessels outside the focal zone of the lithotripter when the vasculature is seeded with cavitation nuclei. The wide distribution of damage suggests that the acoustic field of a lithotripter delivers negative pressures that exceed the cavitation threshold far off the acoustic axis. The findings underscore that conditions permissive for cavitation can lead to dramatic sequelae during SWL.

The role of extracorporeal shockwave lithotripsy in an asymptomatic special patient group with small renal calculi

BACKGROUND AND PURPOSE

Data concerning extracorporeal shock wave lithotripsy (SWL) management of small (< or = 5 mm) asymptomatic renal caliceal stones are lacking in the literature. In this study, we aimed to determine the effectiveness of SWL in a special group of patients who had very small (< or = 5 mm) asymptomatic renal caliceal stones. The group of patients consisted of pilots, gendarmes, and soldiers, such as commandos, for whom treatment was obligatory and who had to be stone free because of their military duties.

PATIENTS AND METHODS

We retrospectively examined SWL data and retrieved information for 84 patients with small asymptomatic renal caliceal stones. The SWL sessions were performed with a Siemens Lithostar lithotriptor. The mean age of the patients was 34 +/- 13 years. The mean stone size was 4.8 +/- 0.4 mm. The mean numbers of shockwaves and energy used were 2707 +/- 1742 and 18 +/- 2 kV, respectively. The location of stones were: 11 right upper calix, 10 right middle calix, 17 right lower calix, 13 left upper calix, 16 left middle calyx, and 17 left lower calix. Eighty-four patients underwent 101 SWL sessions. Only eight patients had second and three patients had third SWL treatments. SWL was performed five times for only one patient. All mean values were realized with an SPSS 10.0 statistical program.

RESULTS

After the first, second, and third SWL sessions, the stone-free rate was calculated as 87%, 93% and 94%, respectively. Only five patients with lower renal caliceal stones were not stone free. The reported complications were macroscopic hematuria necessitating medical attention in four patients, skin ecchymosis in seven patients, severe colic pain in two patients, and urinary-tract infection in one patient. There was no need for hospitalization for these complications.

CONCLUSION

SWL is effective and safe in patients with very small (< or = 5 mm) asymptomatic renal caliceal stones in all locations.

The acute and long-term adverse effects of shock wave lithotripsy

Shock wave lithotripsy (SWL) has proven to be a highly effective treatment for the removal of kidney stones. Shock waves (SWs) can be used to break most stone types, and because lithotripsy is the only noninvasive treatment for urinary stones, SWL is particularly attractive. On the downside SWL can cause vascular trauma to the kidney and surrounding organs. This acute SW damage can be severe, can lead to scarring with a permanent loss of functional renal volume, and has been linked to potentially serious long-term adverse effects. A recent retrospective study linking lithotripsy to the development of diabetes mellitus has further focused attention on the possibility that SWL may lead to life-altering chronic effects. Thus, it appears that what was once considered to be an entirely safe means to eliminate renal stones can elicit potentially severe unintended consequences. The purpose of this review is to put these findings in perspective. The goal is to explain the factors that influence the severity of SWL injury, update current understanding of the long-term consequences of SW damage, describe the physical mechanisms thought to cause SWL injury, and introduce treatment protocols to improve stone breakage and reduce tissue damage.

The association of nephrolithiasis with hypertension and obesity: a review

Kidney stones affect hypertensive patients disproportionately compared to normotensive individuals. On the other hand, some prospective data suggest that a history of nephrolithiasis was associated with a greater tendency to develop hypertension. Newer epidemiologic data also link obesity and diabetes, features of the metabolic syndrome, with nephrolithiasis. In this review, the association of hypertension, diabetes, and obesity with nephrolithiasis is reviewed, and possible pathogenic mechanisms are discussed. Patients with hypertension may have abnormalities of renal calcium metabolism, but data confirming this hypothesis are inconsistent. Higher body mass index and insulin resistance (i.e., the metabolic syndrome) may be etiologic in uric acid nephrolithiasis as increasing body weight is associated with decreasing urinary pH. The possibility that common pathophysiologic mechanisms underly these diseases is intriguing, and if better understood, could potentially lead to better therapies for stone prevention. Both hypertension and stones might be addressed through lifestyle modification to prevent weight gain. Adoption of a lower sodium diet with increased fruits and vegetables and low-fat dairy products, (for example, the dietary approaches to stop hypertension(DASH) diet), may be useful to prevent both stones and hypertension. In those patients in whom dietary modification and weight loss are ineffective, thiazide diuretics are likely to improve blood pressure control and decrease calciuria.

Clinical predictors of stone fragmentation using slow-rate shock wave lithotripsy

AIM

To determine efficacy and clinical predictors of stone fragmentation when using slow-rate shock wave lithotripsy (SWL).

PATIENTS AND METHODS

In total, 116 patients with radiopaque urinary tract stones were randomized into two groups: 57 patients were treated with SWL at 90 shocks/min, and 59 patients were treated with SWL at 120 shocks/min. The efficacy of SWL was evaluated within 1 month after treatment. Patient characteristics, features of stones, and SWL conditions were reviewed. Success rates relating to individual parameters were assessed by using chi-square and Student t tests. All factors were further entered into multivariate logistic regression analysis.

RESULTS

There were no statistically significant differences between the two groups with regard to age, sex, site and size of the stones, renal function, and total number of shock waves. In univariate analysis, the success rate was significantly related to shock wave frequency (p = 0.023), length and width of the stones (p < 0.001), total number of shock waves (p = 0.047), and age (p = 0.049). In multivariate analysis, however, only shock wave rate and stone length remained statistically significant (p = 0.021 and p = 0.046, respectively). The overall success rate was significantly higher in the group treated with 90 shocks/min (p = 0.02). However, this higher success rate was statistically significant only in patients with a stone length > or = 10 mm (50.0 vs. 18.5%, p = 0.019).

CONCLUSION

SWL at 90 shocks/min yielded better outcomes than SWL at 120 shocks/min, particularly in patients with stone lengths > or = 10 mm.

Pediatric nephrolithiasis: does treatment affect renal growth?

OBJECTIVES

The long-term effects of shock wave lithotripsy on the growth of pediatric kidneys are not well defined. Likewise, no long-term data regarding renal growth after ureteroscopy or percutaneous nephrolithotomy have been published. We studied the effect of urolithiasis on renal growth in our pediatric patient population.

METHODS

A total of 165 children were treated for urolithiasis at St. Louis Children's Hospital from March 1993 to December 2003. Of these 165 children, 74 were available for long-term follow-up. Four groups were evaluated: those who underwent shock wave lithotripsy, ureteroscopy, or percutaneous nephrolithotomy, and those who received no intervention. The expected renal length was calculated using Chen's nomogram, and the observed renal length was measured using renal ultrasonography. All measurements were performed by one pediatric radiologist. The expected and observed renal growth was determined by subtracting the renal length at baseline from the length at follow-up, divided by the number of months of follow-up. Statistical analysis used paired data for each treatment group, and comparisons were made on a nonparametric single-rank method.

RESULTS

Of the 74 children, 39 were boys and 35 were girls, with a mean age at treatment of 9 years (range 9 months to 14 years) and a mean follow-up of 6.2 years (range 1.3 to 13.1). In all groups, the comparison between the treated side and nontreated side for expected and actual kidney size and growth was calculated as described. None of the groups had statistically significant differences in the observed or predicted renal growth rates.

CONCLUSIONS

Shock wave lithotripsy, ureteroscopic stone extraction, and percutaneous nephrolithotomy do not appear to impair renal growth.

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

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.