Physical properties of endovascular stents: an experimental comparison.
OBJECTIVE
Different endovascular stent types (AVE Bridge, AVE Bridge X, Memotherm, Palmaz Large, Palmaz Medium, Palmaz-Schatz Long-Medium, Perflex, S.MA.R.T., Symphony, and Wall-stent) of 4 cm length and 8 mm diameter were subjected to standardized physical tests.


METHODS
The metal mass of each stent was assessed by weighing. The balloon-expandable stents were pneumatically tested for hoop strength. In self-expanding stents, radial resistive force and chronic outward force were determined with use of a loop test. Stent delivery system pushability was assessed in a crossover model. Stent radiopacity was analyzed quantitatively.


RESULTS
The hoop strength of the balloon-expandable stents ranged from 15.8 N/cm (Perflex) to 28.9 N/cm (AVE Bridge X). The stent weight increased with greater hoop strength (Perflex, 0.046 g/cm vs. AVE Bridge X, 0.061 g(cm). The self-expanding stents had a radial resistive force between 0.39 N/cm (Wallstent) and 1.7 N/cm (Smart). The flexible balloon-expandable stents showed pushability values between 0.13/N (AVE Bridge) and 0.20/N (Perflex). The self-expanding stents had flexibilities between 0.13/N (Memotherm) and 0.24/N (Symphony). Radiopacity assessed with use of a phantom simulating the iliac region ranged from 92 (Palmaz Large) to 115 (AVE Bridge) on a 256-point gray scale (0 = black, 256 = white).


CONCLUSIONS
There is no stent with ideal physical properties. However, depending on the characteristics of the arterial lesion to be treated, the most appropriate stent can be chosen.
Duda
S H
SH
Department of Radiology, Eberhard-Karls-Universität Tübingen, Germany. stephan.duda@t-online.de
Wiskirchen
J
J
Tepe
G
G
Bitzer
M
M
Kaulich
T W
TW
Stoeckel
D
D
Claussen
C D
CD
D000497:Alloys; D001807:Blood Vessel Prosthesis; D004867:Equipment Design; D055585:Physical Phenomena; D010825:Physics; D013193:Stainless Steel; D015607:Stents / Q000592:standards
D000497:Alloys; D013193:Stainless Steel; C013616:nitinol