nitinol and Kidney-Calculi

Advances in ureteroscope and stone basket design have catapulted ureteroscopy to the forefront of surgical stone management; however, persistent problems such as stone migration continue to challenge urologists. The Escape nitinol stone retrieval basket (Boston Scientific, Natick, MA) is a stone basket designed to capture calculi and facilitate simultaneous laser lithotripsy in situ. We report our initial experience with the Escape basket for the management of urinary calculi and compare the use of this device with other methods of optimizing ureteroscopic stone management.. A prospective evaluation of 23 patients undergoing ureteroscopic holmium:yttrium-aluminum-garnet laser lithotripsy of urinary calculi was performed at two institutions by two surgeons (R.M. and G.M.P). The Escape basket was used to prevent retrograde ureteral stone migration or to facilitate fragmentation and extraction of large renal calculi. Patient demographics and perioperative parameters were assessed.. Twenty-three patients (16 men, 7 women), with a mean age of 55.5 years (range 33-74 yrs) were treated for renal (n = 9) or ureteral (n = 14) calculi. The mean stone diameter was 1.4 cm (range 0.4-2.5 cm), mean fragmentation time was 44.1 minutes (range 10-75 min), and mean energy used was 3.1 kJ (range 0.4-10.6 kJ). No complications were encountered. Eighty-seven percent (20/23) of patients were rendered completely stone free after ureteroscopic laser lithotripsy using the Escape basket. Of the three patients with residual calculi, one patient with a 2.5-cm renal calculus had residual fragments larger than 3 mm, and two patients with large renal calculi had residual fragments smaller than 3 mm.. The Escape basket appears to be safe and effective in preventing stone migration and facilitating ureteroscopic laser lithotripsy and stone extraction.

Topics: Adult; Aged; Alloys; Female; Humans; Kidney Calculi; Lithotripsy, Laser; Male; Middle Aged; Pilot Projects; Treatment Outcome; Ureteral Calculi

Tipless stone baskets facilitate caliceal calculi extraction during flexible ureteroscopy. We evaluated the stone capture rate of 9 commercially available tipless stone baskets in an in vitro model using novice and expert operators.. The Microvasive Zerotip (2.4Fr, 3.0Fr), Cook N-Circle (2.2Fr, 3.0Fr, 3.2Fr), Bard Dimension (3.0Fr, Sacred Heart Medical Halo (1.9Fr), Vantage (1.9Fr) and Circon-ACMI Sur-Catch-NT (3.0Fr) were tested by 3 novice and 3 experienced basket operators. Each operator performed stone extraction of 2, 5 and 8 mm calculi (size determined by digital caliper with 3 repetitions of each basket. The time to extraction of the calculus from a convex based test tube caliceal model was recorded. Statistical analysis was performed using repeated measures ANOVA and Fisher's pairwise comparisons.. After a learning curve of 27 basket retrievals, there was no significant difference in stone capture times between novice (38 +/- 54 seconds) and expert operators (32 +/- 49 seconds, p = 0.174). For total stone capture (all sizes) the Sacred Heart Halo resulted in the most rapid stone extraction (17 +/- 14 seconds) by novices and experts, while the Sur-Catch NT resulted in the slowest stone extraction (78 +/- 90, seconds, p = 0.001). The Halo (14 +/- 9 seconds) and Vantage (19 +/- 12 seconds) baskets were significantly faster for 2 mm calculi than the N-Circle (73 +/- 60 seconds, p = 0.006), Sur-Catch (169 +/- 85 seconds, p = 0.0005) and Dimension (73 +/- 70 seconds, p = 0.017). The Zerotip functioned well for 2 mm calculi in the hands of expert operators (15 +/- 9 seconds) but not novice operators (94 +/- 95 seconds). The Sur-Catch NT was significantly slower for 2 mm calculi than the N-Circle (p = 0.01), Dimension (p =.03), Halo (p =.0005), Vantage (p =.001) and Zerotip (p =.002). For 5 mm calculi the Halo was superior (12 +/- 8 seconds), while the Zerotip were superior for 8 mm calculi (8 +/- 3 seconds) compared to the N-Circle (23 +/- 28 seconds, p = 0.026), Halo (26 +/- 18 seconds, p = 0.021) and Vantage (23 +/- 15 seconds, p = 0.006).. The Sacred Heart Halo and Vantage baskets resulted in the most expeditious stone extraction, especially for 2 to 5 mm calculi while the Microvasive Zerotip was optimal for 8 mm calculi. The Sur-Catch NT had the slowest stone capture rate for all stone sizes. Caliceal models of stone basketing may be useful to train novice urology residents and nursing assistants.

Topics: Alloys; Humans; Kidney Calculi; Kidney Calices; Ureteroscopy

Complications after endoscopic retrieval of kidney and ureter stones are obviously related to the size of the stones as well as the experience of the surgeon and other factors. During the procedure it is sometimes difficult for surgeons to estimate stone size and therefore give prognostic advises. The visual perception of the stone size depends on the shape, colour, distance to the renoscope and dilatation of the ureter. This is the so-called binding problem, because shape, color and direction of motion are processed separately by different population of optical neurons. In order to establish a better prognostic ratio, especially for less experienced surgeons we established an intraoperative semi-quantitative measurement of the stone size supported by a stone basket.. We modified the tipped nitinol stone baskets from the company Urotech with diameters of 2.5, 3.0 and 4 Ch. The handle of this basket has a spring mechanism, which automatically closes the basket and provides a predefined fixation force of the stones within the basket. On the handle we established a non-linear scale in mm by grabbing standardized balls or standardized screws.. The scales are nonlinear because of the nonlinear relation between the diameter of the stone and the distance of the slider. Also the scales differ in between the basket size, because of the different strain conditions due to the different wire sizes and materials or the spring and basket.. This scale could be an important orientation for a surgeon during endourological procedures to estimate stone sizes. It could be used also for the documentation of the size of fragments after an endourologic lithotripsy and could help in the decision for or against an extraction. Finally it could be very interesting for other disciplines like gastroenterology. The scale should be validated in further clinical trials.

Topics: Alloys; Equipment Design; Humans; Kidney Calculi; Size Perception; Ureteral Calculi; Ureteroscopy

Because of increased clinical relevance of retrograde intrarenal surgery (RIRS), a variety of stone retrieval baskets have been introduced into endourology. Differences in shape and material may have consequences in performance and efficacy of RIRS. The aim of the study was to evaluate the in vitro performance of multiple commercially available nitinol retrieval baskets.. Ten manufacturers of baskets for RIRS were invited to participate in this evaluation. The evaluation included measurement of the basket's internal resistance toward deflection, the influence on the deflection angle of a flexible ureteroscope (URF-P5, Olympus), and basket function in maximum deflection of the scope. All measurements were performed five times.. Nine manufacturers, providing a total of 15 baskets, decided to participate in this evaluation. Maximum deflection of the ureteroscope (275 degrees) was achieved in 12 baskets and reduced in 3. In maximum deflection, complete opening of the basket was possible in 13 samples. In one case, partial opening of the basket was possible; one basket failed. The measurement of the basket's internal resistance showed wide variations (5.97 to 38 mm deflection/g), consecutively leading to increased inner radius of the fully deflected scope in 10 of 15 tested samples.. The tested baskets showed wide variations in their resistance toward bending. Influence on overall deflection capacity seems minor, however. On the other hand, higher resistance leads to increased inner radius of the fully deflected renoscope, which may alter functionality. Knowledge about the basket's key feature and differences in basket performance may be crucial to choose the best tool for the patient.

Topics: Alloys; Evaluation Studies as Topic; Humans; Kidney Calculi; Pliability; Ureteroscopy

This paper presents the development of an improved stone retrieval device that uses a newly designed cage of Nitinol wires encompassing a mesh basket made of a material that is laser resistant. Current methods to extract large stones involve imaging, using a laser to fragment the stones and then using existing cage-like baskets to trap the fragments individually and extracting them one at a time. These procedures are tedious, and may result in leaving some fragments behind that can reform causing the need for another procedure. The device presented in this paper will have a mesh-like sack which will consist of a laser resistant material of polytetrafluoroethylene (PTFE) enclosed within a newly designed Nitinol cage. Two alternate designs are provided for the cage in this paper. The handle of the device is revised to allow for a 3 Fr (1 mm) opening such that a laser's fiber optic cable can enter the device. Using this device a laser can be used to fragment the stone, and all the fragments are retained in the basket in both the design options. The basket can then be retracted allowing for the retrieval of all the fragments in one shot. The stone retrieval basket presented in this paper will significantly improve the efficiency and effectiveness of lithotripsy procedures for removal of large kidney and biliary tract stones.

Topics: Alloys; Equipment Design; Equipment Failure Analysis; Gallstones; Humans; Kidney Calculi; Lithotripsy, Laser; Polytetrafluoroethylene

Topics: Alloys; Humans; Kidney Calculi; Pliability; Ureteroscopy

To compare stone retrieval and release from seven basket designs in vitro.. We tested two tipped and one tipless NCompass models, three other tipless Nitinol designs (NCircle, Sur-Catch, and Dimension), and the Segura Hemisphere for their ability to retrieve and release single beads 8, 6, 5.6, and 5 mm diameter and multiple beads 3.6 mm diameter in both a ureteral and a caliceal model in three separate attempts.. In the ureteral model, all baskets were successful in retrieving all sizes of single beads. With multiple 3.6-mm beads, only the NCompass and Dimension designs were able to retrieve at least two of three beads in all attempts. With the exception of the Segura Hemisphere, all designs were successful in releasing all bead sizes. In the caliceal model, only the NCircle, Dimension, and tipless NCompass models were able to retrieve all bead sizes in 100% of the trials. The tipped NCompass and Hemisphere designs were unable to retrieve any beads in this model. The Sur-Catch basket was successful in the retrieval of large beads only. The Dimension articulating design was the only basket able to release all bead sizes in all attempts. The tipless NCompass basket did not release any of the beads once engaged.. Nitinol basket designs show excellent retrieval and release capabilities in the in-vitro ureteral model. The articulating Nitinol basket has the best stone-releasing capability of all baskets tested.

Topics: Alloys; Equipment Design; Humans; Kidney Calculi; Kidney Calices; Models, Biological; Surgical Instruments; Ureteral Calculi

Topics: Alloys; Humans; Kidney Calculi; Rheology; Ureteroscopes; Ureteroscopy

The 7.5 and 9.0 F flexible ureterorenoscopes are used widely in endourology. These scopes, along with new available tools and probes, enable intrarenal ureteroscopic access to renal stones in the lower pole. Following individual clinical experiences the infundibulopelvic angle has to be respected for the selection of different scopes, tools and probes. The aim of this study was to determine the influence of different scopes, tools and probes on the angle of the active and passive flexion of the flexible ureterorenoscope. The angles of the active and passive flexion and maximum irrigation flow of different flexible ureterorenoscope (9.0 F Wolf, 7.5 F Olympus, 7.5 F Storz) were measured repeatedly in vitro using nine different inserted tools and/or probes. In addition, the maximum allowing for easy passage of the nine different tools/probes through the channel of the scope were measured. The Olympus scope without working instrument present, allows for the greatest deflection. The flexible Lithoclast, the non-nitinol baskets, and the 365 microns laser probes significantly inhibit the deflection of all scopes. The greatest deflection with inserted working tool was possible using the Wolf and Storz scopes. Both nitinol tools as well as the 200 microns laser probe had only minimal influence on the deflection. The 200 microns laser probe reduces the irrigation flow from 50 to 28 ml/min. In contrast, the baskets reduce the irrigation flow from 50 to 2 ml/min. There are significant differences of the active and passive flexion depending on the ureterorenoscopes itself and the different tools. In order to perform a successful flexible ureterorenoscopic stone treatment in the lower pole, the inhibition of the flexion of the different scopes together with the individual infundibulopelvic angle must be respected when selecting different tools and probes.

Topics: Alloys; Endoscopes; Humans; Kidney Calculi; Kidney Calices; Lasers; Lithotripsy; Therapeutic Irrigation; Ureteroscopy

Topics: Alloys; Humans; Kidney Calculi; Lithotripsy, Laser; Stents; Ureteroscopy

Lower pole renal access during flexible ureterorenoscopy is often limited by the active deflection capabilities of the ureteroscope. Deterioration in the deflection and flow capabilities of ureteroscopes occurs with the passage of instrumentation through the working channel. We performed in vitro evaluation of a novel technique using unsheathed nitinol baskets to minimize the deterioration in deflection and maximize the irrigant flow associated with instrument passage through the working channel during flexible ureterorenoscopy.. Alterations in the irrigant flow and active deflection of 4 ureteroscopes from different manufacturers were evaluated. Each ureteroscope was evaluated with an empty working channel, and then with sheathed and unsheathed 2.2, 3 and 3.2Fr (Cook Urological, Inc., Indianapolis, Indiana), 2.4 and 3Fr (Microvasive Urology, Natick, Massachusetts) nitinol baskets in the working channel.. With all baskets tested and in all ureteroscopes the deterioration in active deflection and irrigant flow was improved with the unsheathed baskets. The disassembled basket within the working channel allowed an additional 15 to 20 degrees of active deflection. In addition, the disassembled basket allowed for a 2 to 30-fold increase in irrigant flow compared with an intact basket.. The combination of improved deflection and irrigant flow with this technique may improve ureteroscopic access to lower pole renal calculi.

Topics: Alloys; Equipment Design; Humans; In Vitro Techniques; Kidney Calculi; Rheology; Therapeutic Irrigation; Ureteroscopes; Ureteroscopy

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.. 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-micrometer 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.. 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.. 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.

Topics: Adult; Aged; Alloys; Female; Holmium; Humans; Kidney Calculi; Lithotripsy, Laser; Male; Middle Aged; Surgical Instruments; Treatment Outcome; Ureteroscopy

Flexible nephroscopes and ureteroscopes make it possible to see calculi in remote calices, but it is often impossible to remove these with existing technology. Flat-wire baskets impede deflection and can traumatize the papilla. This study compares the performance of a new 3.2F tipless nickel-titanium (Nitinol) basket with that of an existing 3.0F flat-wire basket. Specifications were compared using a 15F nephroscope and a 7.5F flexible ureteroscope in a pig kidney model. A calculus was placed in a calix, and the author and two residents were timed while using both baskets to retrieve the stone. To open fully, the flat-wire basket needed to protrude 1.2 cm further than the tipless basket. The tipless basket did not restrict deflection of the nephroscope, whereas the flat-wire basket limited flexion by 24 degrees and extension by 28 degrees. The tipless basket did not restrict extension of the 7.5F ureteroscope but limited flexion by 10 degrees. The flat-wire basket limited flexion by 79 degrees and extension by 72 degrees. Using the pig kidney model, the three operators took a mean of 5.3, 11.8, and 6.4 seconds to catch the stone with the tipless basket. Using the flat-wire basket, the mean times were 15.3, 34.5, and 28.9 seconds (combined data: 8.2 seconds for the tipless basket and 27.8 seconds with the flat-wire basket; P = 0.0001). Only the flat-wire basket was seen to traumatize the papilla. The Nitinol tipless basket has significant advantages over the flat-wire basket.

Topics: Alloys; Animals; Disease Models, Animal; Endoscopes; Evaluation Studies as Topic; Kidney Calculi; Materials Testing; Swine; Ureteroscopes