A comparison study on physical properties of self-expandable esophageal metal stents.
BACKGROUND
Currently available esophageal expandable stents differ in design, material, and method of deployment. We compared the expansile force and the susceptibility to buckling force in five commercially available stents.


METHODS
The Esophacoil, Wallstent, Ultraflex, Gianturco-Z and Song stents were tested. The middle sections of fully expanded stents were subjected to compression force using a universal tensile testing machine. The distortion of the stent was measured electronically and the expansile force was calculated. Bending moments were applied to the ends of the stents until buckling occurred in the inner parts. The buckling radius was measured as the radius of the inner curvature of the stent when this occurred.


RESULTS
The stents tested were significantly different in their expansile forces and buckling radii. Song stent and Gianturco-Z stent were similar due to their similar designs. Esophacoil was the strongest with regard to withstanding compressive force and angulation force, followed by Wallstent. Ultraflex stent was the weakest in expansile force but withstood angulation force better than the Song and Gianturco stents.


CONCLUSIONS
Esophageal stents differ greatly in their elasticity and resistance to angulation. Knowledge of their mechanical properties will be another helpful factor to consider in selecting the appropriate stent in addition to the geometry and consistency of the tumor.
Chan
A C
AC
Departments of Surgery and Medicine, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China.
Shin
F G
FG
Lam
Y H
YH
Ng
E K
EK
Sung
J J
JJ
Lau
J Y
JY
Chung
S C
SC
D004867:Equipment Design; D004947:Esophagus; D006801:Humans; D008422:Materials Testing; D008670:Metals; D015607:Stents; D013718:Tensile Strength
D008670:Metals