The Journal of Urology
Volume 180, Issue 3 , Pages 969-973, September 2008

In Vitro Evaluation of Nitinol Urological Retrieval Coil and Ureteral Occlusion Device: Retropulsion and Holmium Laser Fragmentation Efficiency

  • Hak J. Lee
    • ,
  • Geoffrey N. Box
    • ,
  • Jose Benito A. Abraham
    • ,
  • Leslie A. Deane
    • ,
  • Erick R. Elchico
    • ,
  • Brian H. Eisner

      Affiliations

    • Financial interest and/or other relationship with Boston Scientific.
    • ,
  • Elspeth M. McDougall

      Affiliations

    • Financial interest and/or other relationship with Astellas, Karl Storz, Intuitive Surgical, Simbionix, Ethicon Endo-Surgical, EndoCare and METI.
    • ,
  • Ralph V. Clayman

      Affiliations

    • Corresponding Author InformationCorrespondence: Department of Urology, University of California-Irvine, 101 The City Dr. South, Building 55, Route 81, Room 304, Orange, California 92868.
    • Financial interest and/or other relationship with Boston Scientific, Cook Urological, Greenwald Surgical, Karl Storz, Astellas, Galil, Omeros, Vascular Technology and Orthopedic Systems.

Departments of Urology, University of California-Irvine, California, and Massachusetts General Hospital (BHE), Boston, Massachusetts

Received 23 December 2007 published online 28 July 2008.

Purpose

Retropulsion of ureteral stones during laser lithotripsy may result in difficult and incomplete stone fragmentation. The Stone Cone® nitinol urological retrieval coil and the NTrap® nitinol ureteral occlusion device have been introduced into clinical practice to possibly limit stone retropulsion and enhance the efficiency of holmium laser (Convergent Laser Technologies, Alameda, California) stone fragmentation.

Materials and Methods

A total of 360 BegoStone Plus phantom stones (Bego USA, Smithfield, Rhode Island) of similar mass and weight were divided into 3 groups, including control, Stone Cone and NTrap. The groups were further subdivided according to fiber size (200 or 400 μm) and pulse width (350 or 700 μsec). These stones were placed in a horizontal pipette 12 mm in diameter, submerged in normal saline and disintegrated at laser settings of 1 J and 10 Hz continuously applied for 300 seconds. Retropulsion in cm and fragmentation efficiency with mass loss in mg were measured after treatment.

Results

The 2 devices were effective for preventing retropulsion. In the control group the mean ± SD retropulsion distance using a 350-μsec pulse width with the 200 and 400 μm fibers was 18.4 ± 5.9 and 14.1 ± 4.6 cm, while it was 6.2 ± 2.6 and 5.6 ± 2.4, respectively, using the 700-μsec pulse width. There was a statistically significant higher loss of stone weight in the Stone Cone and NTrap experimental groups than in the control group (p <0.0001). However, there was no difference between the 2 experimental groups across all groups (p = 0.32).

Conclusions

The Stone Cone and NTrap eliminated retropulsion and equally improved fragmentation efficiency. The maximum efficiency of fragmentation was seen using the 200 μm fiber at a 700-μsec pulse width.

Key Words: ureter, calculi, ureteroscopy, lithotripsy, lasers, solid state

Abbreviations and Acronyms: lbf, foot-pounds, lbm, pound-mass

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 For another article on a related topic see page 1161.

PII: S0022-5347(08)01236-6

doi:10.1016/j.juro.2008.05.016

Refers to article:

  • Investigation of a Novel Degradable Ureteral Stent in a Porcine Model , 18 July 2008

    Boris A. Hadaschik, Ryan F. Paterson, Ladan Fazli, Kenneth W. Clinkscales, Shalaby W. Shalaby, Ben H. Chew
    The Journal of Urology September 2008 (Vol. 180, Issue 3, Pages 1161-1166)

The Journal of Urology
Volume 180, Issue 3 , Pages 969-973, September 2008

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