Dynamic Geometric Analysis of the Renal Arteries and Aorta following Complex Endovascular Aneurysm Repair.

BACKGROUND

Aneurysm regression and target vessel patency during early and mid-term follow-up may be related to the effect of stent-graft configuration on the anatomy. We quantified geometry and remodeling of the renal arteries and aneurysm following fenestrated (F-) or snorkel/chimney (Sn-) endovascular aneurysm repair (EVAR).

METHODS

Twenty-nine patients (mean age, 76.8 ± 7.8 years) treated with F- or Sn-EVAR underwent computed tomography angiography at preop, postop, and follow-up. Three-dimensional geometric models of the aorta and renal arteries were constructed. Renal branch angle was defined relative to the plane orthogonal to the aorta. End-stent angle was defined as the angulation between the stent and native distal artery. Aortic volumes were computed for the whole aorta, lumen, and their difference (excluded lumen). Renal patency, reintervention, early mortality, postoperative renal impairment, and endoleak were reviewed.

RESULTS

From preop to postop, F-renal branches angled upward, Sn-renal branches angled downward (P < 0.05), and Sn-renals exhibited increased end-stent angulation (12 ± 15°, P < 0.05). From postop to follow-up, branch angles did not change for either F- or Sn-renals, whereas F-renals exhibited increased end-stent angulation (5 ± 10°, P < 0.05). From preop to postop, whole aortic and excluded lumen volumes increased by 5 ± 14% and 74 ± 81%, whereas lumen volume decreased (39 ± 27%, P < 0.05). From postop to follow-up, whole aortic and excluded lumen volumes decreased similarly (P < 0.05), leaving the lumen volume unchanged. At median follow-up of 764 days (range, 7-1,653), primary renal stent patency was 94.1% and renal impairment occurred in 2 patients (6.7%).

CONCLUSIONS

Although F- and Sn-EVAR resulted in significant, and opposite, changes to renal branch angle, only Sn-EVAR resulted in significant end-stent angulation increase. Longitudinal geometric analysis suggests that these anatomic alterations are primarily generated early as a consequence of the procedure itself and, although persistent, they show no evidence of continued significant change during the subsequent postoperative follow-up period.