Change in Aortic Neck Diameter after Endovascular Aortic Aneurysm Repair

Implications of aortic neck dilatation following endovascular aneurysm repair (EVAR) are unclear. Previous studies are limited to comparisons of individual, early generation devices. We compared aortic neck dilatation among contemporary stent grafts.

We reviewed preoperative and postoperative computed tomographic angiograms for EVARs performed from 2008-2014. Images were analyzed using 3-dimensional centerline reconstructions. Aortic neck diameter was measured in orthogonal planes at and 10 mm below the lowest renal artery. Device type and main body graft diameter were obtained from operative reports.

Eighty-six patients were analyzed with a median radiologic follow-up of 21.9 months (range: 4-64). Stent grants implanted included 26 Cook Zenith, 26 Gore Excluder, 22 Medtronic Endurant, 10 Endologix Powerlink, and 2 Trivascular Ovation devices. Mean device oversizing was 13.6 ± 11.5% and did not vary by device type (P = 0.54). Most patients (86.0%) experienced increases in aortic neck diameter during follow-up, with a mean increase of 1.3 ± 2.2 mm (5.9 ± 9.3%) and 3.3 ± 0.6 mm (8.9 ± 2.5%) at 30 day and latest follow-up scans, respectively. Repeated-measures analysis further demonstrated a significant increase in mean neck dilatation during follow-up (P < 0.001). Neck dilatation was not significantly different across different devices (P = 0.233). However, there was a moderate positive correlation between percent change in neck diameter and degree of oversizing, which was statistically significant (r_s = 0.41, P < 0.001). Type Ia endoleak was observed in 2 patients and was associated with greater mean neck dilatation (8.8 ± 3.3 mm vs. 3.35 ± 2.71, P = 0.041). There was no relationship between changes in neck diameter and sac regression/expansion.

Aortic neck diameter increases consistently over time following EVAR. The degree of neck dilatation correlates with degree of device oversize but not with device type.