Clinical, Computational, and Experimental Studies of Fenestrated Aortic Stent Graft Rotation

Fenestrated stent grafts are custom-made endovascular devices used to treat abdominal aortic aneurysms, which have fenestrations that align with the branch vessels to provide patency after deployment. Stent graft rotation... [ view full abstract ]

Fenestrated stent grafts are custom-made endovascular devices used to treat abdominal aortic aneurysms, which have fenestrations that align with the branch vessels to provide patency after deployment. Stent graft rotation during deployment can cause fenestration misalignment resulting in branch artery occlusion. We hypothesize that stent graft rotation is caused by an accumulation of rotational energy as the device is moves through the iliac artery, which is released upon deployment. The objective of our study is to determine the causes of this phenomenon.

A retrospective clinical study of 42 fenestrated stent graft implantations identified 15 cases with documented device rotation and 27 cases without rotation. For each case, the iliac artery was segmented from preoperative CT images, and local curvature, torsion, and radius were calculated (Fig. 1a). The average total net torsion was significantly higher in the rotation group (23.5 mm-1 vs. 14.6 mm-1; p=0.0476) with no significant differences in curvature or radius. Assessment of rotation was based on operative notes. We are presently conducting a prospective clinical study to more accurately quantify this rotation.

We are also conducting experimental and computational studies of stent graft delivery and deployment to better understand the factors that cause rotation. An experimental apparatus (Fig. 1b) has been built to simulate stent graft deployment in idealized and patient-specific phantoms, which will enable the measurement of stent graft rotation. Computational models of stent graft delivery and deployment are being developed, starting with the deformation of the iliac artery in response to a rigid guidewire (Fig. 1c).