Shock Wave Lithotripsy Treatment Research Articles

EFFICACY AND COST-EFFECTIVENESS OF EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY FOR SOLITARY LOWER POLE RENAL CALCULI

Purpose We determined the efficacy of extracorporeal shock wave lithotripsy monotherapy and compared its cost-effectiveness with percutaneous nephrolithotomy for the management of lower pole renal calculi. Materials and Methods The efficacy (stone-free rates at 3-months posttreatment) of shock wave lithotripsy with the modified Dornier HM3 * * Dornier Medical Systems, Inc., Marietta, Georgia. machine was determined retrospectively in 114 patients with solitary lower pole renal calculi. Using cost data available from patient billing charges and efficacy data from the literature, the cost-effectiveness for percutaneous nephrolithotomy and shock wave lithotripsy as primary therapy was evaluated. To make this cost-effectiveness comparison, we developed a decision analysis model in which a patient in whom primary therapy failed was rendered stone-free with a secondary percutaneous nephrolithotomy procedure. Results The stone-free rates of solitary lower pole stones with a size range of less than 10, 11 to 20 and greater than 20 mm. were 76, 74 and 33%, respectively, with a single shock wave lithotripsy treatment. Based on average treatment costs for shock wave lithotripsy and percutaneous nephrolithotomy, the model results show that for stone sizes less than 2 cm. primary lithotripsy therapy followed by nephrolithotomy for failed cases is the least costly approach. For stone sizes greater than 2 cm. primary percutaneous nephrolithotomy may be more cost-effective. Conclusions Whereas shock wave lithotripsy with the Dornier HM3 should be considered the initial treatment choice for most lower pole stones less than 2 cm., primary percutaneous nephrolithotomy should be considered for stones larger than 2 cm.

Transurethral Ureterolithotomy in 100 Lower Ureteral Stones

A total of 100 patients with lower ureter stones received transurethral ureterolithotripsy (TUL) using a pulsed dye laser and/or a pneumatic lithotriptor. Extracorporeal shock wave lithotripsy treatment was added in 15 patients because fragments larger than 4 mm had been pushed back to the renal pelvis. The median stone size was 8 mm (range 3–22 mm). Operative time ranged between 3 and 157 min with a median of 30 min. Stone size correlated well with impaction, when impaction was defined as the inability of a guidewire to pass over the stone. Complete removal was defined as total clearance at 1 month without retreatment. The overal stone-free rate was 93%. Among the 7 not-stone-free cases, 5 cases were considered to have been treated successfully because asymptomatic residual fragments were smaller than 4 mm, 1 case required retreatment to become stone free, and 1 case with a silent residual fragment of 8 mm had been followed up for 3 months. The success rate was 98% when successful treatment was defined as total clearance or the presence of asymptomatic residual fragments of 4 mm or less without retreatment. Impaction was not a significant determining factor of stone-free rate (95.7 and 86.7%, respectively, p >0.05) and in situ stone-free rate (TUL alone; 85.7 and 76.7%, respectively, p >0.05). Two minor ureteral perforations were encountered. No patient required percutaneous nephrostomy or open surgery, or showed any late complications. TUL is a safe and successful method in managing lower ureteral stones.

Quantitation of shock wave lithotripsy-induced lesion in small and large pig kidneys.

Shock wave lithotripsy (SWL) is known to cause injury to the kidney. However, it is not known how lesion size varies as the parameters of SWL treatment (number of shocks, kilovoltage, kidney size) are changed. This hypothesis could not be tested because there was no method available to quantitate accurately the SWL-induced renal lesion. A dosage of 2,000 shocks at 24 kV delivered by an unmodified Dornier HM3 lithotripter was applied to the lower pole calyx of the right kidney of small and large pig kidneys. A new method was developed to embed a whole pig kidney for serially sectioning, recording, and digitization. Automated computer color recognition made it possible to discriminate regions of hemorrhage from undamaged tissue and allowed quantitation of the lesion in single sections and in the entire kidney. The new protocol resulted in an accurate identification of sites of hemorrhage and calculations of the volume fraction of injured renal tissue. Lesion size induced in small kidneys was significantly larger than that induced in the larger kidneys (7.6 +/- 1.2% and 1.6 +/- 0.7%, respectively). Computer segmentation of serially sectioned SWL-treated kidneys has determined that kidney size is a risk factor for enhanced renal injury.

Anesthetic management of patients receiving calculus therapy with a third-generation extracorporeal lithotripsy machine.

We reviewed the anesthetic requirements for satisfactory use of a third-generation electromagnetic-source design for extracorporeal shockwave lithotripsy (SWL). Medical records were reviewed for a period of 9 months on all patients receiving anesthesia care for SWL with and without other urologic procedures. The Modulith SL20 was used on 56 ASA Class I-III patients having 87 SWL treatments. Demographic and anesthetic variables were recorded. Complications documented included dysrhythmias, nausea necessitating treatment, and conversion from sedation to regional or general anesthesia. The majority of procedures (83%) were performed on an outpatient basis. Patients were classified as ASA physical status I (27%), II (63%), or III (10%). Monitored anesthesia care with intravenous sedation was utilized in 93% of cases. Of these cases, 78 involved a combination of intravenous propofol, fentanyl, and midazolam; the remaining 3 involved propofol, alfentanil, and/or midazolam. The mean treatment duration was 36 minutes. Patients were discharged within 1 hour after procedure completion in 77 cases (89%). Nausea necessitating treatment was rare (3%). The mean dose of propofol administered with SWL as the only procedure was 272 +/- 112 mg. When SWL was combined with other urologic procedures, the mean dose of propofol was 334 +/- 121 mg. Continuous intravenous propofol infusion provides excellent procedural conditions for SWL on the Modulith SL120, a third-generation lithotripter.

Minor residual fragments after extracorporeal shockwave lithotripsy: spontaneous clearance or risk factor for recurrent stone formation?

The aim of this study was to follow the fate of residual stone fragments (RF) < 5 mm after extracorporeal shockwave lithotripsy (SWL) over a sufficiently long period to determine how many are spontaneously cleared and after what time interval. A further aim was to clarify their role in clinical outcome and stone recurrence and regrowth. The clinical and radiologic data of 266 patients were analyzed. The patients were followed up for a mean of 387 days. After SWL, 55 patients (21%) had residual fragments < 5 mm in diameter. There were no significant differences between the stone-free patients and those with RF with regard to age, sex, relevant medical history, or SWL treatment. After a mean follow-up of 2.5 years, 12.7% of the residual fragments had not passed spontaneously, but all of them were clinically silent and located exclusively in the lower calices and the proximal ureter. Only 2% of the patients with RF showed stone regrowth, and no stone recurrences were observed within the follow-up period. In conclusion, although a minor pathophysiological role of RF < or = 5 mm cannot be discounted in recurrence and regrowth of kidney stones after SWL, more invasive attempts to clear all minor fragments do not seem warranted.

Glycosaminoglycan content of Ca-oxalate stone matrix. Effect of this factor on stone fragility.

To evaluate the fragility of Ca-oxalate monohydrate stones in terms of high energy shock wave effectivity, we measured the glycosaminoglycan (GAG) content of the organic stone matrix of 35 patients who had undergone extracorporeal shock wave lithotripsy (ESWL) treatment for renal pelvic stones. The patients were classified into 3 different groups with respect to the rate of stone disintegration. While group I consisted of patients in whom only one ESWL session was needed to complete disintegration, in group II there were patients requiring 3 or more sessions for complete stone disintegration. On the other hand, patients in whom no sign of disintegration was observed despite 3 ESWL sessions constituted group III. Following this procedure, comparative evaluation of the GAG content of the stone matrix per dry stone weight in each group revealed a statistically significant difference between the first 2 and the 3rd group (p < 0.05). Our results indicated that as the GAG content of the stone matrix decreased, the efficiency of the shock waves on stone disintegration also prominently decreased, disintegration being impossible in some cases. On the other hand, the stones which were found to have higher amounts of GAGs in the organic matrix tended to be more fragile and were easily disintegrated with shock waves. In our study group the chemical composition of Ca-oxalate monohydrate stones, e.g. the matrix GAG content, seemed to be important with regard to the disintegrative effect of high energy shock waves.

Early detection of infected ureteral obstruction after SWL employing C-reactive protein.

Infection of the obstructed upper urinary tract is a severe complication of stone disease. Early detection and therapy is crucial to prevent septicemia. The authors investigated prospectively whether C-reactive protein (CRP) might act as a marker for the early detection of infected upper urinary tract obstruction. The serum concentration of CRP was compared with the classic markers of inflammation--white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and temperature--in the follow-up of 85 patients undergoing 173 extracorporeal shockwave lithotripsy (SWL) treatments. Post-SWL, 69% of the patients showed dilation of the upper tract on ultrasonography and 16.5% became symptomatic and required intervention. In this group, the mean CRP value was increased 18-fold, whereas the WBC count, ESR, and temperature were not markedly raised. In contrast, patients with no need for additional treatment showed no more than a 2-fold increase in CRP. C-Reactive protein seems to be a useful indicator for the early detection of infected upper urinary tract obstruction.

Use of extracorporeal shock wave lithotripsy for treatment of nephrolithiasis and ureterolithiasis in five dogs

Use of extracorporeal shock wave lithotripsy for treatment of nephrolithiasis and ureterolithiasis in five dogs

Fibrous Coagulum: A New Cause of Retained Fragments Following Extracorporeal Shock Wave Lithotripsy

Purpose A previously unrecognized cause of retained fragments following extracorporeal shock wave therapy is identified. Materials and Methods Nine patients referred for percutaneous stone extraction following failure of multiple shock wave lithotripsy treatments had retained fragments embedded in soft tissue. The stones were evaluated by chemical analysis and the tissue was evaluated histologically. Results All stones contained calcium and histopathology confirmed the presence of fibrous tissue. Radiographs were unable to predict the presence of the substance preoperatively. Conclusions We identified fibrous coagulum as a cause of retained fragments following shock wave lithotripsy. The material is soft tissue and cannot be ablated by further shock wave lithotripsy. These findings confirm that repeated shock wave lithotripsy is contraindicated, since stone fragmentation and passage may be inhibited by fibrous coagulum.

Cardiac Arrhythmias During Nonsynchronized Extracorporeal Shock Wave Lithotripsy

Purpose We evaluated the occurrence of cardiac arrhythmias during nonsynchronized extra-corporeal shock wave lithotripsy. Materials and Methods A total of 125 nonsynchronized shock wave lithotripsy treatments was performed using a spark plug lithotriptor. Results Asymptomatic unifocal ventricular premature contractions occurred during 23 treatments (18.4 percent) and were more frequent during therapy on the right side (p less than 0.05). Among patients undergoing multiple sessions only 1 exhibited ventricular premature contractions during treatment. No correlation was demonstrated between ventricular premature contractions and patient age, gender, presence of heart disease, stone size and location within the collecting system (kidney or ureter), presence of a ureteral catheter or nephrostomy tube, mode of anesthesia or number of shock waves. Conclusions Nonsynchronized shock wave lithotripsy can be accomplished safely in most patients.

Dry extracorporeal shock wave lithotripsy for treatment of ureterolithiasis and nephrolithiasis in a dog

Dry extracorporeal shock wave lithotripsy for treatment of ureterolithiasis and nephrolithiasis in a dog

Subcapsular Hematoma due to ESWL: Risk Factors

A study of 4,247 shockwave lithotripsy treatment was performed to identify and analyze the risk factors for the development of post-extracorporeal shock-wave lithotropsy hematomas. The Dornier HM-3 and HM-4 lithotriptors were used. We recognized 23 hematomas in 23 patients (0.54%). Various factors were examined to identify the certain predisposing risk factors. There was no correlation of sex, age, stone number, stone size, stone location, number of shock waves and voltage used with the occurrence rate of hematoma. We found that patients with pre-existing hypertension and especially those with poor control of it had a significantly increased incidence of perinephric hematoma.

The cavitation threshold of human tissue exposed to 0.2-MHz pulsed ultrasound: Preliminary measurements based on a study of clinical lithotripsy

Evidence of acoustic cavitation was identified in the form of transient echoes in ultrasound B-scan images of patients receiving extracorporeal shock-wave lithotripsy treatment on a Storz Modulith SL20. This lithotripter generates 10-μs duration pulses with a centre frequency of 0.2 MHz at a pulse repetition frequency of 1 Hz. The visual appearance of B-scan images was examined in a total of 30 patients and a quantitative analysis of echogenicity changes was carried out in six cases involving lithotripsy treatment of stones in the renal pelvis. In these patients new echoes were identified in images unaffected by movement artefacts and were found to occur in perinephric fat and adjacent muscle and kidney tissue at positions close to the axis of the shock-wave field between 1 and 2 cm in advance of the indicated beam focus of the lithotripter. The echogenicity within each region increased significantly above the background level when the output of the lithotripter was increased above a threshold value. The acoustic pressures corresponding to this threshold were measured in water using a calibrated PVDF membrane hydrophone. After correction for attenuation in tissue the cavitation thresholds, in terms of the temporal peak negative pressure, are found to lie between 1.5 MPa and 3.5 MPa in all six cases. Interpretation of the measured values in terms of the likely threshold at the higher frequencies used in diagnostic ultrasound is considered using a theoretical model.

104 気泡と衝撃波との干渉

This is an experimental study visualizing the interaction of air bubbles with underwater shock waves and is related to the investigation of tissue damage induced during extracorporeal shockwave lithotripsy treatment. Two optical visualization techniques, such as holographic interferometry and conventional photography were intensively used. The result of visualization revealed that various collapse patterns exist depending on properties of surrounding materials and the tissue damage could be generated mainly due to liquid jets formed inside the bubbles.

Primary extracorporeal shockwave lithotripsy in management of large bladder calculi.

Large bladder calculi are often outside the range of treatment with conventional endoscopic lithotrites because of either anatomic factors or the mechanical limits of available instruments. Alternative methods of cystolithotripsy: ultrasonic, electrohydraulic, or laser, can prove time-consuming or even hazardous, so that open surgery is often the most expeditious option. We report our experience using Dornier HM3 extracorporeal shockwave lithotripsy (SWL) for initial bladder stone reduction preparatory to transurethral litholapaxy and definitive treatment of any underlying obstructive pathology. Primary cystolitholapaxy was judged impractical in these 24 patients (21 adults and 3 children) presenting 31 large bladder stones (mean size 35.6 mm). In all patients, primary transpelvic SWL was followed immediately by endoscopic evacuation of stone debris or cystolitholapaxy. In addition, 10 of the 24 patients (42%) underwent a definitive endoscopic operation for treatment of an underlying obstructive lesion at either the same or a follow-on session. Morbidity was minimal, and the mean hospital stay after the initial SWL treatment was 3.5 days. In our experience, Dornier SWL has proved invaluable in enabling cystolitholapaxy of very large bladder calculi that would otherwise require protracted and difficult endoscopic manipulation or open surgery.

Oral cholecystography compared to cholescintigraphy for evaluation of cystic duct patency prior to ESWL treatment

In a prospective, blinded study of 109 patients with cholecystolithiasis, oral cholecystography and 99Tcm-EHIDA cholescintigraphy were compared in terms of reliability for demonstrating cystic duct patency: one of the prerequisites for extracorporeal shock wave lithotripsy (ESWL) treatment of cholecystolithiasis. Patients with a positive result on one or both tests were regarded as having cystic duct patency. Patients with negative and uncertain result of both tests or one of each were regarded as having no cystic duct patency. Concordance between the two tests was obtained in 93 of 109 patients. The diagnostic reliability of cholescintigraphy and oral cholecystography were 95 and 86%, respectively (P < 0.05), suggesting a more precise determination of gallbladder filling with scintigraphy.

Incidence of bacteremia and bacteriuria in patients with non-infection-related urinary stones undergoing extracorporeal shock wave lithotripsy.

In a prospective pilot study, 26 patients with non-infection-related renal or ureteric stones and sterile urine were examined for evidence of bacteriuria and bacteremia following extracorporeal shock wave lithotripsy (SWL). Blood samples were obtained for aerobic and anaerobic bacterial culture at the end of, and 1 hour after, the SWL procedure. Urine cultures were performed 24 hours before and after treatment. Bacteremia was recorded in 7.7% of the patients immediately after SWL but in no patient at 1 hour after treatment. None of the patients manifested significant bacteriuria or post-SWL fever. These findings support the contention that, provided the urine is sterile and a negative history of urosepsis is available, antibiotic prophylaxis is unnecessary in patients with non-infected renal stones submitted to SWL treatment.

Extracorporeal Shock Wave Lithotripsy for Treatment of Ureterolithiasis in Patients with Cystinuria

Ten of 42 patients with cystinuria admitted for extracorporeal shock wave lithotripsy (ESWL) treatment had ureterolithiasis. Of these, 3 had bilateral stones, 2 had only 1 functioning kidney, and 2 had stones in both the kidney and ureter on the same side. Only 1 patient was on medical treatment at the time of referral. After initiation of medical treatment for cystinuria, 2 patients were discharged without further intervention, 1 was discharged after placement of a ureteric stent and 10 were treated with ESWL. After an average of 1.5 ESWL treatment sessions per ureter, 8 patients became stone-free and in the remaining 2, ureteroscopy was required to complete the treatment. Problems associated with the ESWL treatment of cystine stones are discussed. It was concluded that ESWL is the treatment of choice for ureterolithiasis in patients with cystinuria because it is effective and is the least invasive procedure even in patients with cystinuria.

Role of extracorporeal shock-wave lithotripsy in treatment of urolithiasis in patients with medullary sponge kidney

In an effort to identify the role of extracorporeal shock-wave lithotripsy (ESWL) in the treatment of patients with medullary sponge kidney, a retrospective review of our experience with the Dornier HM-3 lithotriptor is presented. From 1986–1991 17 patients with medullary sponge kidney ranging in age from twenty-eight to fifty-eight years received 31 treatments to a total of 24 renal units. Follow-up ranged from four to fifty-six months with an average follow-up of twenty-five months. ESWL appears to have a role in the treatment of symptomatic urolithiasis in patients with medullary sponge kidney. There may also be some benefit in treating parenchymal calcifications. No significant side effects from the treatment were noted.

Calculus Disease in Duplex System – Role of Extracorporeal Shockwave Lithotripsy

We report 8 patients with urolithiasis in a duplex system. These patients (7 males and 1 female) underwent 16 extracorporeal shock wave lithotripsy (ESWL) treatments. Five had renal and 3 had ureteral stones. The mean stone size was 21 mm (12-54 mm). Five patients had incomplete and 3 had complete duplication, of which one had an associated horseshoe kidney. Retrograde ureteropyelography was done in all the patients and in 7 a JJ stent was inserted. The JJ stent could not be inserted in 1 patient with incomplete duplication and retrograde catheterization with saline infusion was used as an auxiliary procedure. One patient with complete duplication had stones in both the ipsilateral ureters with a stone bulk of 54 mm and required two JJ stents. Only 1 paediatric patient required general anaesthesia. The 3-month stone-free rate was 100%.