Type I and collateral flow in experimental aneurysm models treated with stent-grafts.

Objective: To evaluate the influence of a collateral branch on the evolution of type I leaks after endovascular aneurysm repair in an experimental model.

Methods: Bilateral aneurysms were constructed in the common iliac arteries of 12 dogs by using venous patches. A collateral branch was added on one aneurysm on one side by implantation of the sacroiliac trunk on the sac. Balloon-expandable stent-grafts were implanted 2 months later. In six dogs, type I endoleaks were created on the side with the collateral branch by using plastic deformation of the stent-graft (group 1). Stent-grafts were fully expanded on the contralateral side in the same dogs (group 2, control group). In the remaining six dogs, type I endoleaks were created on the side without the collateral branch (group 3), and stent-grafts were fully expanded on the side with the collateral branch, creating a type II endoleak (group 4). Follow-up imaging was performed with Doppler ultrasonography and angiography until the animals were sacrificed at 3 months. Leaks were classified as major, moderate, or absent with use of findings at imaging and pathologic examinations.

Results: No endoleaks were observed in group 2 (control group). Endoleaks were persistent in 83% of aneurysms in groups 1 (5/6 type I), 3 (5/6 type I), and 4 (5/6 type II). Type I leaks were major in three of six cases when associated with a collateral branch (group 1) and moderate when they were not (group 3; P < .05). Before sacrifice, larger aneurysmal diameters were observed only in group 1 (110% +/- 18) as compared with control group 2 (85% +/- 12) (P < .05).

Conclusions: More prominent leaks and larger aneurysms are observed when a collateral branch is associated with a type I endoleak.