Updates in Endourology and Shock Wave Lithotripsy

Highlights from the 20th World Congress on Endourology and SWL

MEETING REVIEW Updates in Endourology and Shock Wave Lithotripsy Highlights from the 20th World Congress on Endourology and SWL, 18th Basic Science Research Symposium, September 19–22, 2002, Genoa, Italy [Rev Urol. 2003;5(3):182–185] © 2003 MedReviews, LLC Key words: Endourology • Shock wave lithotripsy • Calcium oxalate stones • Ureteroscopy • Laparoscopic surgery • Thermal ablation • Virtual ureteroscopy • Benign prostatic hypertrophy • Prostatic ethanol injection he 20th World Congress on Endourology and SWL and the 18th Basic Science Research Symposium meetings were held in Genoa, Italy on September 19–22, 2002. The 1200 urologists who attended enjoyed the excellent venue and superb organization of these meetings. Herein, an overview is presented of the Basic Science Research Symposium. T Calcium Oxalate Stone Formation Oxalate has previously been demonReviewed by Dean G. Assimos, MD, Department of Urology, Wake Forest University School of Medicine, WinstonSalem, NC 182 VOL. 5 NO. 3 2003 strated to cause time- and dosedependent effects on the growth and viability of porcine and canine renal epithelial cell lines. Oxidative stress has been shown to cause cell injury in these in vitro models. Menon and associates,1 from the Vattikuti Urology Institute, Detroit, demonstrated this in a human renal epithelial cell line, HK-2. These events may play a role in the formation of calcium oxalate stones. A significant amount of oxalate that is excreted is derived from endogenous hepatic oxalate synthesis via the oxidation of glyoxylate to oxalate. Although the oxidation of glycolate to glyoxylate has been REVIEWS IN UROLOGY thought to be the main source of glyoxylate production, other sources may exist. Shah and colleagues,2 from Wake Forest University School of Medicine, Winston-Salem, NC, reported that, when cultured hepatic cells (Hep G2) were incubated with hydroxyproline, production of glyoxylate and oxalate increased. This may link endogenous oxalate synthesis to diet, as hydroxyproline is a major constituent of animal protein. The formation of calcium oxalate stones results from interactions between genetic and environmental factors. Some of these influences were profiled at this meeting. Monga and colleagues,3 from the Department Endourology and SWL Updates of Urology at the University of Minnesota, Minneapolis, reported that, in identical twins, urinary calcium, citrate, sulfate, and phosphate excretion and urinary calcium oxalate supersaturation were strongly influenced by genotype. Ogan and associates,4 from the University of Texas Southwestern Medical Center, Dallas, reported that consumption of cranberry juice reduced urinary pH and increased calcium excretion in normal subjects as well as in stone formers. However, an increase in the relative supersaturation of calcium oxalate occurred only in the latter group. Shock Wave Lithotripsy Shock wave lithotripsy (SWL) may cause microvascular and interstitial renal damage, which has been attributed to cavitation energy and resultant free-radical injury. Sarica and colleagues,5 from the Department of Urology at the University of Gaziantep, Gaziantep, Turkey, showed that adrenomedullin, nitric oxide, and heat shock protein 70 may be released in response to these injuries. Terranova and associates,6 from Duke University Medical Center, Durham, NC, reported that both vitamin E and citrate attenuated shock wave– induced free radicals in an in vitro model using cultured renal epithelial cells (Madin Darby canine kidney [MDCK)] cell line). The ability to predict stone fragility with SWL would permit better selection of candidates for this type of therapy. Stern and colleagues,7 from Northwestern University Medical School, Chicago, found that stone density, assessed by measuring Hounsfield units, was a better predictor of SWL success than was stone size. Paterson and associates,8 from Indiana University School of Medicine, Indianapolis, reported on the use of a micro–computed tomography scanner to study the internal structure of stones. They predict that this may be used in the future to assess SWL stone fragility and allow clinicians to select the optimal therapy for patients. New Ureteroscopic and Percutaneous Procedures There were a number of interesting presentations on technologies used during ureteroscopic and percutaneous procedures. Conlin and associates,9 from Oregon Health and Science University, Portland, and Perry and colleagues,10 from the UCLA Department of Urology, Los Angeles, reported on the use of a new flexible ureteroscope that has active second- with an 810-nm pulsed diode laser provided excellent hemostasis and closure of the renal collecting system in a porcine partial nephrectomy model. This same group14 found that both pledgeted compression sutures and parenchymal resection with a 980-nm diode laser facilitated partial nephrectomy in swine. Ramakumar and associates15 from the University of Arizona, Tucson, demonstrated that a polyethylene glycol-based hydrogel was an effective hemostatic agent for partial nephrectomy performed in swine. Andreoni and colleagues,16 from the Federal University of São Paulo, São Paulo, Brazil, reported that perfusion of the The saline-augmented probe reduces tissue impedance, thus facilitating tissue ablation. ary deflection. This instrument facilitates the ability to access and treat problems in the lower pole collecting system. Landman and associates,11 from Washington University, St. Louis, demonstrated that placement of a ureteral access sheath at the time of percutaneous renal surgery results in decreased intrarenal pressure and increased irrigant flow, compared with the use of a retrograde ureteral catheter or occlusion balloon. Watterson and associates,12 from the University of Western Ontario, London, Canada, reported that embedding stent materials with oxalate-degrading enzymes resulted in a reduction in encrustation in a rabbit model. Novel Adjuncts for Laparoscopic Surgery A number of novel adjuncts for laparoscopic surgery were reported. Ogan and colleagues13 from University of Texas Southwestern Medical Center, Dallas, reported that tissue welding porcine kidney with hypertonic solution caused significant renal shrinkage that resulted in a 40% decrease in the size of incision for extraction. Thermal Ablative Techniques in Renal Cell Carcinoma Thermal ablative techniques for management of the primary tumor in select patients with renal cell carcinoma are being utilized more frequently. Matlaga and associates,17 from Wake Forest University School of Medicine, Winston-Salem, NC, performed a study in which 10 patients with renal cell carcinoma underwent salineaugmented radiofrequency ablation of their tumors just prior to nephrectomy. The saline-augmented probe reduces tissue impedance, thus facilitating tissue ablation. The study authors reported that 8 of the 10 tumors were completely devitalized, as assessed by nicotinamide adenine dinucleotide (NADH) vital staining. Failure occurred in a patient with an VOL. 5 NO. 3 2003 REVIEWS IN UROLOGY 183 Endourology and SWL Updates continued 8-cm tumor and in a case in which the temperature did not reach an adequate level. Vanappledorn and colleagues,18 from the Department of Urology at the University of Miami, evaluated this technology in a rabbit model and found no evidence of significant injury to the collecting system when large lesions were created. Marcovich and associates,19 from the Long Island Jewish Medical Center, New Hyde Park, NY, reported that interruption of renal blood flow at the time of radiofrequency ablation of porcine renal tissue did not have a significant impact on the size of the resulting lesion. Advances in Image-Based Technology A number of advancements in image-based technology were presented. Russell and colleagues,20 from the Mayo Clinic, Rochester, Minn, reported that simulated tumors as small as 3 mm could be detected with 100% sensitivity with virtual cystoscopy and virtual ureteroscopy. Liatsikos and associates,21 from the University of Patras, Greece, reported that virtual ureteroscopy could be used to accurately determine patency in patients with metallic ureteral stents. Jacomides and colleagues,22 from University of Texas South- western Medical Center, Dallas, and Watterson and associates,23 from the University of Western Ontario, London, Canada, found that use of virtual endoscopic simulators accelerated the development of endourologic skills. Sweet and associates,24 from the University of Washington, Seattle, have validated the effectiveness of a virtual reality simulator of transurethral resection of the prostate. Innovative Approaches for Patients with Benign Prostatic Hypertrophy A number of innovative concepts for managing patients with benign prostatic hypertrophy (BPH) were highlighted. Plante and colleagues,25 from the University of Vermont, Burlington, evaluated the effectiveness of both transperineal and transurethral prostatic ethanol injections in a canine model. Transperineal injections resulted in prostatic tissue necrosis, but this was complicated by extraprostatic tissue necrosis. The lesions produced with transurethral alcohol injection were variable in size and location. Gutierrez-Aceves and associates,26 from the University of Guadalajara, Mexico, reported on transurethral ethanol injection in 89 men with BPH. There were significant reductions in symptom scores and prostatic volume, an increase in urinary flow rate, and improvement in quality of life 6 months after the procedure. Kuo and colleagues,27 from the Methodist Hospital Institute for Kidney Stone Disease, Indianapolis, investigated the tissue ablative properties of a side-firing holmium laser in an in vitro model (beef kidney) and found that an energy setting of 3.2 joules delivered at 25 Hz resulted in the greatest tissue ablation. Conclusion Some of the aforementioned advances will provide a platform for translational research, whereas others will be incorporated into clinical practice. This should provide better insights into the disease processes that form the basis of our practice and facilitate the delivery of care for persons afflicted with these disorders. References 1. 2. 3. 4. Menon M, Koul HK, Bhandari A, et al. Oxalate is toxic to hk-2 cells, a line of proximal tubular epithelial cells from normal human kidney [abstract]. J Endourol. 2002;16(suppl 1):A13. Shah O, Holmes RP, Kennedy M, et al. Hydroxyproline metabolism to glycolate and oxalate in Hep G2 cells [abstract]. J Endourol. 2002;16(suppl 1):A13. Monga M, Groppo E, Meyer RS, Hargens A. Genetic determination of urinary stone risk in identical twins [abstract]. J Endourol. 2002; 16(suppl 1):A15. Ogan K, Gettman M, Adams-Huet B, et al. Effect of cranberry juice on calcium stone risk [abstract]. J Endourol. 2002;16(suppl 1):A15. Main Points • Shock wave lithotripsy may cause microvascular and interstitial renal damage, which has been attributed to cavitation energy and resultant free-radical injury. • New technologies, such as a flexible ureteroscope with active secondary deflection and placement of a ureteral access sheath, may facilitate percutaneous and ureteroscopic surgery. • One study reported that 8 out of 10 tumors were completely devitalized in patients with renal cell carcinoma who underwent salineaugmented radiofrequency ablation. • Virtual cystoscopy and virtual ureteroscopy proved effective in developing endourologic skills and simulating transurethral resection of the prostate. • A study of 89 men with benign prostatic hypertrophy demonstrated that the use of a transurethral ethanol injection significantly reduced symptom scores and prostatic volume, increased urinary flow rate, and improved quality of life 6 months after the procedure. 184 VOL. 5 NO. 3 2003 REVIEWS IN UROLOGY Endourology and SWL Updates 5. 6. 7. 8. 9. 10. 11. 12. Sarica K, Balat A, Erbagci A, et al. Effects of shock wave lithotripsy on plasma and urinary concentrations of nitric oxide and adrenomedullin [abstract]. J Endourol. 2002;16(suppl 1):A17. Terranova S, Delvecchio FC, Brizuela RM, et al. Citrate and vitamin E blunt the SWL-induced free radical surge of an in-vitro MDCK cell culture model [abstract]. J Endourol. 2002;16(suppl 1):A16. Stern JA, Kimm S, Chang C-H, et al. Hounsfield unit density accurately predicts stone free rates from extracorporeal shock wave lithotripsy [abstract]. J Endourol. 2002;16(suppl 1):A18. Paterson RF, Kuo RL, Lingeman JE, et al. Comparison of multi-detector helical computed tomography with ultra-high resolution CT in the analysis of kidney stone structure [abstract]. J Endourol. 2002;16(suppl 1):A14. Conlin M, Patel A, Schulam P, et al. Improved ureteroscopic access to the lower pole: results with a prototype flexible ureteroscope incorporating active secondary deflection [abstract]. J Endourol. 2002;16(suppl 1):A29. Perry K, Shvarts O, Chin J, Schulam PG. Improved functional deflection and access to lower pole renal calculi with new dual deflection flexible ureteroscope [abstract]. J Endourol. 2002;16(suppl 1):A29. Landman J, Ryan RT, Teichman JMH, et al. Holmium: YAG laser beam profile and efficiency during lower pole ureteroscopic lithotripsy [abstract]. J Endourol. 2002;16(suppl 1):A29. Watterson JD, Cadieux PA, Beiko DT, et al. Oxalate-degrading enzymes from oxalobacter formigenes: a novel device coating to reduce urinary tract biomaterial-related encrustation [abstract]. J Endourol. 2002;16(suppl 1):A14. 13. Ogan K, Jacomides L, Napper C, et al. Sutureless laparoscopic heminephrectomy using laser tissue soldering in the porcine model [abstract]. J Endourol. 2002;16(suppl 1):A21. 14. Wilhelm DM, Ogan K, Lindberg G, et al. Laparoscopic partial nephrectomy with a diode laser: porcine results [abstract]. J Endourol. 2002;16(suppl 1):A22. 15. Ramakumar S, Park E, Nelson J, et al. Comparison of biodegradable peg-based hydrogels for use as a hemostatic agent in a porcine laparoscopic partial nephrectomy model [abstract]. J Endourol. 2002;16(suppl 1):A21. 16. Andreoni CR, Silva FD, Bonfim A, et al. Intracorporeal renal shrinking: a new approach for laparoscopic organ removal in a porcine model [abstract]. J Endourol. 2002;16(suppl 1):A20. 17. Matlaga BR, Zagoria RJ, Woodruff RD, et al. Phase II trial of saline-augmented radiofrequency ablation of renal cancer: evaluation of the kill zone [abstract]. J Endourol. 2002;16(suppl 1):A31. 18. Vanappledorn S, Leveillee RJ, Patel VR, et al. Saline-augmented radiofrequency ablation of rabbit kidneys: do large lesions cause delayed injury to the collecting system? [abstract]. J Endourol. 2002;16(suppl 1):A31. 19. Marcovich R, Aldana J, Morgenstern N, et al. Histological characteristics following radiofrequency ablation of porcine kidney with and without hilar control [abstract]. J Endourol. 2002;16(suppl 1):A23. 20. 21. 22. 23. 24. 25. 26. 27. Russell S, Kawashima A, Vrtiska T, et al. Detection of simulated tumors in a phantom bladder model using 3-dimensional (3D) computed tomography (CT) virtual cytoscopy [abstract]. J Endourol. 2002;16(suppl 1):A8. Liatsikos E, Kagadis G, Karnabatidis D, et al. Ureteral metallic stents: application of virtual endoscopy for ureteral patency control [abstract]. J Endourol. 2002;16(suppl 1):A12. Jacomides L, Ogan K, Cadeddu JA, Pearle MS. Comparison of residents and inexperienced medical students on an endoscopic virtual reality simulator [abstract]. J Endourol. 2002;16(suppl 1):A10. Watterson JD, Beiko DT, Kuan JK, Denstedt JD. Acquisition of ureteroscopy skills using a computer-based virtual reality endourological simulator: validation of the URO Mentor simulator [abstract]. J Endourol. 2002;16(suppl 1):A10. Sweet R, Kowalewski T, Oppenheimer P, et al. Validation of the University of Washington virtual reality TURP simulator as a training tool [abstract]. J Endourol. 2002;16(suppl 1):A5. Plante M, Gross A, Zvara P. Intraprostatic ethanol chemoablation via transperineal versus transurethral injection [abstract]. J Endourol. 2002;16(suppl 1):A6. Gutierrez-Aceves J, Saita A, Seman D, et al. Histological changes of the prostate gland after transurethral ethanol ablation [abstract]. J Endourol. 2002;16(suppl 1):A6. Kuo RL, Paterson RF, Siquiera TM, et al. Invitro use of the duotome 550 micron Ho-YAG fiber: a comparison of setting effectiveness [abstract]. J Endourol. 2002;16(suppl 1):A7. VOL. 5 NO. 3 2003 REVIEWS IN UROLOGY 185