The impact of stent design on proximal stent-graft fixation in the abdominal aorta: an experimental study

OBJECTIVE: to study the proximal fixation of different aortic stent grafts in comparison to a hand-sewn anastomosis. DESIGN: experimental study. MATERIAL: the infrarenal aorta of 16 human cadavers were exposed, left in situ and transected 3 cm above the aortic bifurcation to mimic an infrarenal aortic neck. Stent grafts were deployed through a sheath 5 cm into the aorta. Ancure, Talent, Vanguard, Zenith and a Palmaz based stent graft were assessed. In addition a polyester graft was anastomosed to the aorta by running sutures. Distal force was applied to the grafts in increments of 0.5 Newton until the stent grafts were completely dislodged from the aorta. The displacement force (DF) was thereby determined. RESULTS: a force of 150 N (140-160) applied to the hand-sewn graft resulted in tearing of the aorta, without breakage of the sutures. The median displacement force was for Talent 4.5 N (1.3-5.5), Vanguard 9.0 N (3. 5-12), Ancure 12.5 N (12-14), Zenith 24 N (23-26.5) and Palmaz 25 N (17-25). Ballooning the stent after deployment improved fixation in some cases. CONCLUSIONS: a sutured anastomosis fixates a graft better than any stent design tested. Hooks and barbs improve the fixation of self-expandable stents. Balloon dilatation of the proximal stent after deployment might increase fixation further. Balloon expandable stents seem to provide good fixation without the use of hooks and barbs.