Abdominal Aortic Aneurysm Research Today is a free monthly online journal that collates and summarizes the latest research about Abdominal Aortic Aneurysm, including details on aaa (abdominal aortic aneurism), cardiac disease, treatment, symptoms, surgery.

Iliac fixation length and resistance to in-vivo stent-graft displacement.

Arko FR, Heikkinen M, Lee ES, Bass A, Alsac JM, Zarins CK

Division of Vascular Surgery, Stanford University Medical Center, Stanford University, CA, USA. frank.arko@utsouthwestern.edu <frank.arko@utsouthwestern.edu>

PURPOSE: Migration of endovascular stent grafts has been related to the security of proximal device fixation to the aortic neck. This study evaluated the importance of iliac fixation in preventing longitudinal in vivo device displacement of a modular, externally supported stent graft. METHODS: Experimental ovine infrarenal aneurysms (n = 8) were treated with a fully supported, modular, bifurcated stent graft (AneuRx, Medtronic, Santa Rosa, Calif). Minimum iliac fixation length (1 cm) was used in four animals and iliac extender modules were used to achieve maximum iliac fixation in four animals. Suture anastomosis of bifurcated polyester grafts to the infrarenal aorta served as controls (n = 8). Aortic grafts were displaced in vivo by applying downward traction to a guidewire that was passed over the iliac flow divider and brought out both femoral arteries. The displacement force needed to initiate stent-graft migration was recorded and compared with the force needed to disrupt the sutured anastomosis. RESULTS: There was no difference in animal weight (88.8 +/- 2.5 kg vs 87.5 +/- 2.9 kg), aortic neck diameter (12.7 +/- 0.9 mm vs 13.4 +/- 1.1 mm), aortic neck length (23.2 +/- 0.9 mm vs 21.8 +/- 2.4 mm), experimental aneurysm size (24.7 +/- 1.1 mm vs 24.2 +/- 2.0 mm), or iliac artery diameter (9.0 +/- 1.5 mm vs 9.3 +/- 0.5 mm) among the groups. Iliac fixation length was 31.0 +/- 0.3 mm in the maximum iliac fixation group and 11 +/- 0.25 mm in the minimum fixation group (P < .0001). Peak displacement force to initiate migration was 30.2 +/- 5.5 N (range, 25 to 38) in animals with maximum iliac fixation compared with 18.1 +/- 3.7 N (range, 13 to 21) in those with minimum fixation (P = .01). The force needed to disrupt the control surgical anastomosis was 40.6 +/- 7.5 N (range, 31 to 50) (P < .01). CONCLUSIONS: Maximizing iliac fixation length increases the longitudinal in vivo force needed to displace a fully supported stent graft by 67%. This suggests that increasing iliac fixation length may reduce the long-term risk of migration in patients undergoing endovascular aneurysm repair.

Published 5 May 2005 in J Vasc Surg, 41(4): 664-71.
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