Changes in aneurysm morphology and stent-graft configuration after endovascular repair of aneurysms of the descending thoracic aorta.

OBJECTIVE

We sought to study changes in morphology and stent-graft configuration of descending thoracic aortic aneurysms after endovascular repair.

METHODS

Twenty-three patients treated with custom-made stent-grafts were studied. The stent-graft consisted of continuous, stainless-steel Z stents mounted within a polyester graft. In the last 11 cases the stents were interconnected with 3 longitudinal wires. Contrast-enhanced spiral computed tomography was performed preoperatively and at 1, 3, and every 6 months postoperatively. Angiography was used preoperatively and at 1-year follow-up. Proximal and distal necks were assessed for diameter and length. Aneurysm diameter, endoleaks, stent-graft migration, and changes in stent-graft configuration were evaluated.

RESULTS

During follow-up (median, 18 months; range, 1-48 months), excluded aneurysms decreased in diameter by 4 mm (0.5-10 mm, P =.0018). Endoleaks prevented size decrease. Five patients displayed neck dilatation, 4 at both the proximal and distal fixation sites and 1 only distally. In 7 (30%) patients there was proximal migration of the distal end of the stent-graft. Three (13%) patients displayed both distal migration of the proximal end of the stent-graft and proximal migration of the distal end of the stent-graft. There was a significant correlation between stent-graft kinking and appearance of proximal or distal stent-graft migration (P =.05 and P =.0007, respectively). In no case did the migration lead to appearance of an endoleak before intervention was performed.

CONCLUSION

Excluded descending thoracic aortic aneurysms decrease in size on midterm follow-up. A subgroup of patients prone to neck dilatation might exist. A combination of neck dilatation and vector forces acting on stent-grafts in the tortuous thoracic aorta might lead to stent-graft migration.