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 configu ration of descending thoracic aortic aneurysms after endovascular repair. Methods: Twenty-three patients treated with custom-made stent-grafts were s tudied. The stent-graft consisted of continuous, stainless-steel Z stents m ounted within a polyester graft. In the last 11 cases the stents were inter connected with 3 longitudinal wires. Contrast-enhanced spiral computed tomo graphy was performed preoperatively and at 1, 3, and every 6 months postope ratively. Angiography was used preoperatively and at 1-year follow-up. Prox imal and distal necks were assessed for diameter and length. Aneurysm diame ter, endoleaks, stent-graft migration, and changes in stent-graft configura tion 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%) pat ients there was proximal migration of the distal end of the stent-graft. Th ree (13%) patients displayed both distal migration of the proximal end of t he stent-graft and proximal migration of the distal end of the stent-graft. There was a significant correlation between stent-graft kinking and appear ance of proximal or distal stent-graft migration (P = .05 and P = .0007, re spectively). 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.