Geometrical changes in Anaconda endograft limbs after endovascular aneurysm repair: A potential predictor for limb occlusion

The emergence of limb occlusion after endovascular aneurysm repair may be related to the conformational changes between the endograft structure and the patient's anatomy. This study analyzed detailed geometric changes of Anaconda endograft (Terumo Aortic, Inchinnan, Scotland, UK) limbs during the cardiac cycle–based computed tomography on serial imaging after graft implantation. Fifteen patients (mean age 72.8 ± 3.7 years; 14 men) underwent postoperative electrocardiogram-gated computed tomography scans according to a prospective study design between April 2014 and May 2017. Changes in curvature, length of the limbs, and distances between successive stent rings (inter-ring distance) of the endograft limbs during a 2-year follow-up period were quantified using meticulous image processing methods involving image registration, centerline extraction, and model-based stent-ring segmentation. From discharge to 24 months, mean curvature increased significantly by 9.6 m^–1 (standard deviation [SD], 11.1 m^–1; 95% confidence interval [CI], 3.4 to 15.8 m^–1; P =.002) for the right limbs and by 6.1 m^–1 (SD 9.4 m^–1; 95% CI, 0.8 to 11.5 m^–1; P =.21) for the left limbs. The length of the right limbs decreased significantly, by 9.5 mm (SD 7.6 mm; 95% CI, 3.5 to 15.6 mm; P =.002); the length of the left limbs decreased by 10.1 mm (SD 5.1 mm; 95% CI, 5.9 to 14.2 mm; P <.001). The minimal inter-ring distance decreased by 0.36 mm (SD 0.26 mm; 95% CI, 0.17 to 0.55 mm; P <.001) for the right limbs and 0.35 mm (SD 0.19 mm; 95% CI, 0.21 to 0.49 mm; P <.001) for the left limbs. Cardiac pulsatility–induced changes in curvature, limb length, and inter-ring distance were negligible (2%, 0.3% and 0.3%, respectively). Changes in the geometry of the Anaconda endograft limbs after endovascular aortic aneurysm repair were observed during a 2-year follow-up manifest as an increase in curvature, shortening of the stent-graft limbs, and a corresponding decrease in inter-ring distance. These stent-graft conformational changes could result in inward folding of the graft fabric, which may relate to the emergence of limb occlusion. Further investigation of these metrics in a larger cohort involving patients with and without occlusions may allow determination of their predictive value.