PURPOSE: The authors evaluated the ability of an aortic balloon-expand
able endovascular stent-graft to prevent rupture in a model of spontan
eously rupturing abdominal aortic aneurysms in sheep. MATERIALS AND ME
THODS: Aneurysms were created in 16 sheep by inserting a 60 x 18-mm se
gment of the left internal jugular vein, end-to-end anastomosed, to th
e sectioned infrarenal abdominal aorta. The sheep were randomly assign
ed into two groups; eight animals underwent endovascular implantation
of an 80 x 12-mm balloon expandable stent-graft (group A), and eight w
ere only followed up (group B). RESULTS: In group B, seven of eight an
imals had died of aneurysmal rupture by 3 months. In group A, six of t
he eight aortic aneurysms Were immediately excluded, and six animals w
ere alive at 3 months without rupture. The 3-month survival rate was 1
00% in group A and 12% in group 8 (P = .0023). Macro-and microscopic a
nalysis of the section of the aorta in which the stent-graft had been
placed revealed rapid retraction of the aneurysmal sac. CONCLUSION: Pl
acement of an endovascular stent-graft induced regression of a branchl
ess aneurysm and prevented rupture.