In-vivo evaluation of flow characteristics of novel metal ureteral stent.
OBJECTIVE
To characterize the flow of a novel ureteral stent composed of a nickel-cobalt-chromium-molybde-num alloy and compare it with flow in a standard ureteral stent.


METHODS
Six 6F Resonance stents and six 6F standard Black Beauty ureteral stents were placed in six Yucatan minipigs, with each pig serving as its own control. Flow assessment was performed on all stents via a nephrostomy tube delivering a standard rate of 0.9% saline at 35 cm H(2)O. Flow studies on the standard stents encompassed extraluminal (i.e., lumen of stent occluded with a guidewire), intraluminal (i.e., ureter secured to stent with a constricting suture), and combined (i.e., open lumen without constricting suture) flow. In the Resonance stent, only combined and intraluminal flow could be addressed, as there is no access to the lumen of this stent.


RESULTS
With the Resonance stent, intraluminal flow was much greater than combined flow, with mean values of 5.15 mL/min and 2.50 mL/min, respectively (P = 0.057; SD = 7.73). Intraluminal flow was similar to combined flow in the 6F standard stent, with mean values of 7.34 mL/min and 7.30 mL/min, respectively (P = 0.88; SD = 1.76). The standard stent had significantly greater combined flow than the Resonance stent (P = 0.023) but not intraluminal flow (P = 0.247). Of note, whereas it was possible to occlude the 6F standard stent completely with a ureteral ligature (i.e., no guidewire placed in the lumen), it was not possible to occlude the Resonance stent regardless of how tightly the suture was tied.


CONCLUSIONS
The Resonance metal alloy stent provides less overall flow than a standard stent. However, under circumstances of extrinsic ureteral compression sufficient to occlude a standard stent (e.g., extrinsic compression plus an internal guidewire), the metal stent continues to provide satisfactory drainage.
Blaschko
Sarah D
SD
Department of Urology, University of California-Irvine Medical Center, Orange 92868, California, USA.
Deane
Leslie Allan
LA
Krebs
Alfred
A
Abdelshehid
Corollos S
CS
Khan
Farhan
F
Borin
James
J
Nguyen
Alex
A
McDougall
Elspeth M
EM
Clayman
Ralph V
RV
D000497:Alloys; D000818:Animals; D005260:Female; D015607:Stents; D013552:Swine; D013556:Swine, Miniature; D014513:Ureter / Q000502:physiology*; D014563:Urodynamics / Q000502:physiology*
D000497:Alloys