Mechanical Behavior to Overexpansion of Cobalt Chromium Compared with Stainless Steel Stents in the Abdominal Aorta of Hypercholesterolemic Rabbits

pp. 158-162

Abstract

Objectives: The aim of this study was to analyze the behavior to overexpansion of cobalt chromium stents compared with stainless steel stents.

Methods: Twenty New Zealand rabbits were used, fed with a diet supplemented with 1% cholesterol. Animals were divided into two groups. Group 1 (n=10) received 3.0 mm cobalt chromium stents deployed at 20 atmospheres and group 2 (n=10) 3.5 mm stents deployed at 10 atmospheres. These stents were compared with a previous series of 20 animals with stainless steel stents, divided into the same two groups. A third group with conventional diet was used as control. Intravascular ultrasound (IVUS) was performed to assess the degree of elastic recoil and also the degree of symmetry using “intertrust angles”.

Results: In group 1 of cobalt chromium stents, mean elastic recoil was 0.11±0.13 mm, (3.21% recoil) and in group 2 this was 0.3±0.12 mm, (8.26% recoil) (p=0.002). In group 1 mean elastic recoil was 0.28±0.18 mm (8.21% recoil) and in group 2 this was 0.10±0.11 mm (2.79% recoil) (p <0.001).

Conclusions: In cobalt chromium stents, elastic recoil was lower in overexpanded stents, whereas in stainless steel stents, elastic recoil in higher in overexpanded stents. No differences in symmetry were observed between the different groups.