Mechanical properties of various z-stent designs: an endovascular stent-grafting perspective.
OBJECTIVE
To comparatively assess the mechani-cal behavior of various clinically relevant Z-stent designs.


METHODS
A total of 16 Z-stents of original, biliary, spiral, and double-skirted designs (n=4 for each) were constructed using similar specifications for all. Stents were then evaluated for stiffness, snap opening force (SOF), flexibility, and displacement force using a novel tensiometer. Differences among the stents were determined using statistical methods. Stents explanted from dog aorta after a mean follow-up of 13 months were examined under a scanning electron microscope for surface defects.


RESULTS
Forces required for about 50% reduction in diameter were 1.88 +/- 0.16 N, 3.81 +/- 0.21 N, 2.76 +/- 0.22 N, and 3.35 +/- 0.19 N for original, biliary, spiral, and skirted designs, respectively. Differences among the four designs were statistically significant at almost all points of measurement (P < 0.0001). Biliary and skirted designs showed higher SOF values in the early measurements. Stents explanted from dog aorta after a mean duration of 13 months showed no obvious corrosion or breakage in the wire struts.


CONCLUSIONS
Significant differences exist among the various Z-stent designs in terms of their mechanical properties. Understanding them should help to select the appropriate stent for a given lesion. 316L stainless steel shows a favorable long-term tissue interaction.
Bashar
Abul Hasan Muhammad
AH
The First Department of Surgery, Hamamatsu University School of Medicine, Shizuoka, Japan. basharahm@yahoo.com
Kazui
Teruhisa
T
Washiyama
Naoki
N
Terada
Hitoshi
H
Yamashita
Katsushi
K
Haque
Mohammad E
ME
D017130:Angioplasty / Q000295:instrumentation*; D000818:Animals; D001696:Biomechanical Phenomena; D004867:Equipment Design; D006801:Humans; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D015607:Stents