Nitinol stone retrieval-assisted ureteroscopic management of lower pole renal calculi
ABSTRACT Objectives. Current ureteroscopic intracorporeal lithotripsy devices and stone retrieval technology allow for the treatment of calculi located throughout the intrarenal collecting system. Difficulty accessing lower pole calculi, especially when the holmium laser fiber is used, is often encountered. We retrospectively reviewed our experience with cases in which lower pole renal calculi were ureteroscopically managed by holmium laser fragmentation, either in situ or by first displacing the stone into a less dependent position with the aid of a nitinol stone retrieval device.Methods. Thirty-four patients (36 renal units) underwent ureteroscopic treatment of lower pole renal calculi between April 1998 and November 1999. Lower pole stones less than 20 mm were primarily treated by ureteroscopic means in patients who were obese, in patients who had a bleeding diathesis, in patients with stones resistant to shock wave lithotripsy, and in patients with complicated intrarenal anatomy, or as a salvage procedure after failed shock wave lithotripsy. Lower pole calculi were fragmented with a 200-μm holmium laser fiber by way of a 7.5F flexible ureteroscope. For those patients in whom the laser fiber reduced the ureteroscopic deflection, precluding re-entry into the lower pole calix, a 3.2F nitinol basket or a 2.6F nitinol grasper was used to displace the lower pole calculus into a more favorable position, allowing easier fragmentation.Results. In 26 renal units, routine in situ holmium laser fragmentation was successfully performed. In the remaining 10 renal units, a nitinol device was passed into the lower pole, through the ureteroscope, for stone displacement. Only a minimal loss of deflection was seen. Irrigation was significantly reduced by the 3.2F nitinol basket, but improved with the use of the 2.6F nitinol grasper. This factor did not impede stone retrieval in any of the patients. At 3 months, 85% of patients were stone free by intravenous urography or computed tomography.Conclusions. Ureteroscopic management of lower pole calculi is a reasonable alternative to shock wave lithotripsy or percutaneous nephrolithotomy in patients with low-volume stone disease. If the stone cannot be fragmented in situ, nitinol basket or grasper retrieval, through a fully deflected ureteroscope, allows one to reposition the stone into a less dependent position, thus facilitating stone fragmentation.
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ABSTRACT: The optimal management of lower pole renal calculi is controversial. We compared shock wave lithotripsy (SWL) and ureteroscopy (URS) for the treatment of patients with small lower pole stones in a prospective, randomized, multicenter trial. A total of 78 patients with 1 cm or less isolated lower pole stones were randomized to SWL or URS. The primary outcome measure was stone-free rate on noncontrast computerized tomography at 3 months. Secondary outcome parameters were length of stay, complication rates, need for secondary procedures and patient derived quality of life measures. A total of 67 patients randomized to SWL (32) or URS (35) completed treatment. The 2 groups were comparable with respect to age, sex, body mass index, side treated and stone surface area. Operative time was significantly shorter for SWL than URS (66 vs 90 minutes). At 3 months of followup 26 and 32 patients who underwent SWL and URS had radiographic followup that demonstrated a stone-free rate of 35% and 50%, respectively (p not significant). Intraoperative complications occurred in 1 SWL case (unable to target stone) and in 7 URS cases (failed access in 5 and perforation in 2), while postoperative complications occurred in 7 SWL and 7 URS cases. Patient derived quality of life measures favored SWL. This study failed to demonstrate a statistically significant difference in stone-free rates between SWL and URS for the treatment of small lower pole renal calculi. However, SWL was associated with greater patient acceptance and shorter convalescence.The Journal of urology 06/2008; 179(5 Suppl):S69-73. · 3.75 Impact Factor
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ABSTRACT: We developed an optical system to quantify in vitro tip movement of the Lithoclastdouble dagger flexible probe, and correlated various physical parameters of the vibrating probe tip with resultant stone fragmentation. A noncontact optical measurement system was developed to quantify in vitro tip movement of the Lithoclast flexible probe. This system and an in vitro fragmentation model were used to determine the tip displacement, velocity, impact momentum, impact energy and stone fragmentation of the flexible probe at 5 deflection angles between 0 and 48 degrees, and the 2 pneumatic pressure levels of 2.0 and 2.5 bar. An increase in maximum probe tip displacement, velocity, impact momentum and energy, and stone fragmentation was seen as the pneumatic pressure was increased from 2.0 to 2.5 bar. A progressive decrease in these parameters was demonstrated as the probe tip was deflected, especially at deflection angles greater than 24 degrees. Impact momentum appears to be the physical parameter most closely correlated with stone fragmentation efficiency. The optical measurement system and in vitro fragmentation model developed allow one to quickly and reliably assess the performance of flexible pneumatic probes in vitro. This system can be used for general bench testing and basic research that can provide critical information for the design of more effective and efficient flexible pneumatic lithotripsy probes.The Journal of Urology 12/2000; 164(5):1735-9. · 3.75 Impact Factor
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ABSTRACT: BACKGROUND AND PURPOSE: Autosomal dominant polycystic kidney disease (ADPKD) manifests with renal and extrarenal abnormalities and is inherited in an autosomal dominant fashion. In addition to multiple renal cysts, abnormalities such as liver cysts (80%), pancreatic cysts, splenic cysts, pulmonary cysts, berry aneurysms in the distribution of arterial circle of Willis (8%), colonic diverticula, mitral valve prolapse, etc., can be present. The condition will develop in half of the offspring of affected persons because of its 100% penetrance. Nephrolithiasis in patients with ADPKD is not infrequent and, given the importance of preservation of renal function in this subset of patients, a clear understanding of the management options available and their advantages and disadvantages is absolutely essential and critical in better patient outcomes. This article is an endeavor in this direction and provides a review of the current available literature. MATERIALS AND METHODS: An electronic database search of Medline, Embase, and Cochrane library was performed to search for the available literature in January 2010 with no restrictions in terms of date or language. The search terms used were ADPKD, nephrolithiasis, percutaneous nephrolithotomy, shockwave lithotripsy, flexible ureterorenoscopy, congenital kidney disorders, etc., separately and in various combinations. The articles so extracted were scrutinized for relevance and selected for the review.Journal of endourology / Endourological Society 10/2010; 24(10):1557-61. · 1.75 Impact Factor