How to improve results with extracorporeal shock wave lithotripsy

OBJECTIVE

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.

METHODS

A systematic literature review was performed to identify studies of SWL treatment parameters.

RESULTS

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.

CONCLUSIONS

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.

The evolution of lasers in urology

The world's first laser was developed by Theodore Maiman in 1960. Over the course of the past five decades, this technology has evolved into a highly specialized entity, also finding a niche market in the field of urology. Lasers obtained from various lasing mediums producing amplified light of different wavelengths have been tested for urological applications. Today, these lasers are most commonly used in the surgical management of benign prostatic hyperplasia and as intracorporeal lithotripters. Other uses include ablation of various urologic tumors and incising strictures of the upper- and lower urinary tract. A continuous process of evolution of this technology is taking place, resulting in surgical lasers becoming ever safer, more effective, and more affordable.

Ureteroscopy: The standard of care in the management of upper tract urolithiasis in children

Objectives

Advances in technology and the continued evolution in the design of ureteroscopes now permit a primary endoscopic approach to the upper urinary tract of pediatric patients on a routine basis to treat a diverse group of conditions that include urolithiasis, hematuria and strictures. The purpose of this review article is to demonstrate that ureteroscopic lithotripsy is now to be considered the standard of care in the management of upper tract urolithiasis in the pediatric patient, replacing shockwave lithotripsy (ESWL) as the first line of therapy. Additionally, the article will discuss the available endoscopic equipment and the lessons learned over the years to optimize the success of these procedures in children.

Materials and Methods

A systematic review of articles written about ureteroscopy (URS) in the contemporary urological literature (1990-2009) on PubMed was undertaken. The success rates and complications of pediatric ureteroscopic procedures were abstracted from the identified publications and the results were tabulated and compared with the success rates of shockwave lithotripsy.

Results

In over 832 URS cases, there was a 5.9% complication rate and a stone-free rate of 93.4%. The stone-free rates of URS are superior to those obtained with the published success rates with ESWL of 80.3% in 1,839 cases.

Conclusions

The safety and outcomes of ureteroscopic lithotripsy in the management of pediatric urolithiasis now justify that this treatment modality be considered the standard of care and first line of therapy in the management of children who present with upper tract stones.

Combined electrohydraulic and holmium: YAG laser ureteroscopic nephrolithotripsy of large (>2 cm) renal calculi

Percutaneous nephrolithotripsy (PCL) is a standard treatment for renal calculi >2 cm. Modern flexible ureteroscopes and accessories employing the complementary effects of electrohydraulic lithotripsy (EHL) and Ho:YAG laser lithotrites can treat these renal calculi in a minimally invasive fashion with similar or superior results.

New instrumentation in percutaneous nephrolithotomy

Percutaneous nephrolithotomy (PCNL) is the procedure of choice for removing large, complex, and/or multiple renal calculi. Since its first description in 1976, PCNL techniques and equipment have evolved to maximize procedural efficacy, safety, and reproducibility. We reviewed current literature from January 2004 to November 2009 using Medline search regarding PCNL instrumentation and technology. Additional equipment discovered during the review process without published Medline evidence was summarized from manufacturer brochures and data. Included in this review are summaries of intracorporeal lithotriptors and accessory equipment, stone manipulation devices, PCNL tract sealants, and a digital rigid nephroscope. The evolution of these devices from their predecessors has increased the instrumentation options for the treating urologist and may represent more effective technology for the percutaneous treatment of large renal stones.

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.

Comparison of the effectiveness of crushing concrements in the urinary tract with the use of holmium laser and sonotrode

INTRODUCTION

Holmium lasers and ultrasound probes are widely used in urinary stone lithotripsy. The authors present a comparison of both methods in urinary stones lithotripsy.

MATERIALS AND METHODS

We analyzed 164-patients who underwent endoscopic lithotripsy. Ninety-eight of them (group I) were treated with the holmium laser Omni-Pulse Max 80 and were compared to the other 66-patients (group II) who were operated on with an ultrasound probe (sonotrode). Prior to the procedures, all patients were exposed to urological ultrasound and radiological imaging in order to localize the stone. The state where the stones were invisible in the radiological and renal ultrasound imaging that was performed after the operation was considered to be effective. Patients were operated under intravenous general or subepidural anesthesia.

RESULTS

The effectiveness of laser lithotripsy in the bladder amounted to 100% (25 of 25 patients). In the case of stones localized in the ureter it reached 89%. The total effectiveness of the procedure reached 92% (90 out of 98 procedures). In group II, the total effectiveness of the procedure reached 79% (52 out of 66 procedures). In group I, two cases the inflammatory changes of the ureter made the endoscopy impossible. These two patients were operated with open surgery. In one case, the laser lithotripsy was complicated with a perforation of the ureter.

CONCLUSION

The results prove that laser lithotripsy is a method of high effectiveness with a low risk of complication. It might surpass sonotrode and become its alternative. Both methods have both advantages and disadvantages.

Scrotal hematoma resulting from extracorporeal shock wave lithotripsy for a renal calculus: a sign of retroperitoneal hemorrhage

We report a rare case of a patient presenting with scrotal hematoma associated with retroperitoneal hemorrhage after extracorporeal shock wave lithotripsy (ESWL). We propose a mechanism for the formation of scrotal hematoma and its importance as a sign of retroperitoneal hemorrhage.

Update on ureteroscopy instrumentation

The authors present an objective review of what is new in endourology instrumentation, based on up-to-date scientific data gathered from meetings, state-of-art lectures and current literature. The main scope of this review is to highlight the most recommended device options for each step of an ureteroscopy, in order to offer best care to patients.

A review of computational methods in materials science: examples from shock-wave and polymer physics

This review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment.

A review of computational methods in materials science: examples from shock-wave and polymer physics

This review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment.

Percutaneous endoscopic holmium laser lithotripsy for management of complicated biliary calculi

BACKGROUND AND OBJECTIVES

Advances in endoscopic techniques have transformed the management of urolithiasis. We sought to evaluate the role of such urological interventions for the treatment of complex biliary calculi.

METHODS

We conducted a retrospective review of all patients (n=9) undergoing percutaneous holmium laser lithotripsy for complicated biliary calculi over a 4-year period (12/2003 to 12/2007). All previously failed standard techniques include ERCP with sphincterotomy (n=6), PTHC (n=7), or both of these. Access to the biliary system was obtained via an existing percutaneous transhepatic catheter or T-tube tracts. Endoscopic holmium laser lithotripsy was performed via a flexible cystoscope or ureteroscope. Stone clearance was confirmed intra- and post-operatively. A percutaneous transhepatic drain was left indwelling for follow-up imaging.

RESULTS

Mean patient age was 65.6 years (range, 38 to 92). Total stone burden ranged from 1.7 cm to 5 cm. All 9 patients had stones located in the CBD, with 2 patients also having additional stones within the hepatic ducts. All 9 patients (100%) were visually stone-free after one endoscopic procedure. No major perioperative complications occurred. Mean length of stay was 2.4 days. At a mean radiological follow-up of 5.4 months (range, 0.5 to 21), no stone recurrence was noted.

CONCLUSIONS

Percutaneous endoscopic holmium laser lithotripsy is a minimally invasive alternative to open salvage surgery for complex biliary calculi refractory to standard approaches. This treatment is both safe and efficacious. Success depends on a multidisciplinary approach.

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.

Current opinions in sialolithiasis diagnosis and treatment

The introduction, 15 years ago, of extracorporeal shock wave lithotripsy in the treatment of salivary gland calculi, has changed the therapeutic approach in these patients. Aim of this study was to evaluate the efficacy of lithotripsy in sialolithiasis, after 10 years follow-up. A review has been made of the literature to establish current opinions in diagnosis and treatment of sialolithiasis. The role of ultrasonography, radiography and, in particular, of sialomagnetic resonance imaging in diagnosis of salivary lithiasis has been evaluated. The greater efficiency of the extracorporeal shock wave lithotripsy treatment for parotid, compared to submandibular calculi, has been demonstrated (57% versus 33%). In 68% of our patients, lithotripsy was resolutive after 10 years. Ultrasonograpy should be considered first choice examination in diagnosis of salivary calculi. Sialo-magnetic resonance imaging is a recent, non-invasive diagnostic procedure with the advantage of no radiation exposure, and with better definition of anatomical and functional state of glandular parenchyma and duct, compared to other available techniques.

Lithotripsy in the laparoscopic era

OBJECTIVES

The overall prevalence of gallstones in the United States is between 10% and 15%. Eighty-five percent of common bile duct (CBD) stones can be removed by endoscopic sphincterotomy with basket or balloon extraction, or both. The introduction of mechanical lithotripsy improved the results up to 90%. We present one case of retained CBD stone after 2 failed endoscopic sphincterotomies and balloon/basket extraction treated by electrohydraulic lithotripsy (EHL).

METHODS

A fifty-year-old man underwent ERCP for suppurative cholangitis. Because of the failure of stone extraction, he was taken to the operating room for an open cholecystectomy and CBD exploration. The intraoperative cholangiogram showed contrast flowing into the duodenum. Seven weeks later, the patient presented with mild pancreatitis, and a T-tube cholangiogram revealed a stone impacted in the distal CBD. Percutaneous balloon extraction was again unsuccessful.

RESULTS

The patient underwent a single 2.5-hour session of EHL via the T-tube tract. Mild pulmonary edema occurred intraoperatively. Complete clearance of the CBD was obtained without the need for additional ERCP.

CONCLUSIONS

EHL is a valid and effective option for difficult retained common bile duct stones after failed ERCP.

Risk factors for recurrent bile duct stones after endoscopic papillotomy

BACKGROUND

The long term outcome of endoscopic papillotomy (EPT) is not well known. The aims of this study were to clarify the clinical course of post-EPT patients and to detect predictors for bile duct stone recurrence.

METHODS

A total of 1042 consecutive patients who underwent EPT for bile duct stones from December 1975 to September 1998 were prospectively followed up. Patients were divided into four groups according to gall bladder (GB) status: "acalculous GB" group, "calculous GB" group, "cholecystectomy" group, and "prior cholecystectomy" group. Reliable follow up information was obtained for 983 (94.3%) of the 1042 patients. The following factors were considered in the evaluation of predisposing risk factors for recurrence of bile duct stones: age, sex, gall bladder status, periampullary diverticulum, number of bile duct stones, diameter of bile duct stones, diameter of bile duct, lithotripsy, precutting, pneumobilia, and early complications.

RESULTS

Recurrence occurred in 111 patients. The "acalculous GB" group was less prone to recurrence than the "prior cholecystectomy" group and the "calculous GB" group. The relative risks (RR) for the latter two compared with the former group were 2.26 (95% confidence interval (CI) 1.24-4.14; p=0.0078) and 2.16 (95% CI 1.21-3.87; p=0.0093), respectively. Other prognostic factors were lithotripsy (RR 2.37; 95% CI 1.47-3.81; p=0.0004) and pneumobilia (RR 1.57; 95% CI 1.01-2.43; p=0.044).

CONCLUSIONS

Gall bladder status, lithotripsy, and pneumobilia were significantly related to bile duct stone recurrence after EPT.

The treatment of lower pole renal calculi in 2003

The optimal treatment of patients with lower pole renal calculi is still being defined. Shock wave lithotripsy, percutaneous nephrolithotomy, and ureteroscopy are all currently utilized to treat patients with this condition. These methods have yielded varying degrees of success. The influence of collecting system anatomy on shock wave lithotripsy results remains controversial. Ongoing randomized, prospective trials evaluating the efficacy of all of these respective therapeutic options will, it is hoped, determine the best approaches for this patient cohort.

Urinary tract imaging

This article reviews the current imaging investigations usually required in the work-up of common urinary tract problems such as urinary tract infection, colic, trauma, hematuria and renal failure. Radiological therapeutic techniques such as percutaneous nephrostomy for drainage of obstructed systems and percutaneous nephrolithotomy for treatment of renal calculi are briefly mentioned. The virtual elimination of percutaneous or open surgery for renal and upper urinary tract stones, resulting from the installation of the first and only Canadian extracorporeal shock wave lithotripter in the Department of Radiology at the Vancouver General Hospital is also discussed.