Endograft apposition and infrarenal neck enlargement after endovascular aortic aneurysm repair.

Background: Sufficient apposition and oversizing of the endograft in the aortic neck are both essential for durable endovascular aneurysm repair (EVAR). These measures are however not regularly stated on post-EVAR computed tomography angiography (CTA) scan reports. In this study endograft apposition and neck enlargement (NE) after EVAR with an Endurant II(s) endograft were analyzed and associated with supra- and infrarenal aortic neck morphology.

Methods: In 97 consecutive elective patients, the aortic neck morphology was measured on the pre-EVAR CTA scan on a 3mensio vascular workstation. The distance between the lowest renal artery and the proximal edge of the fabric (shortest fabric distance, SFD), and the shortest length of circumferential apposition between endograft and aortic wall (shortest apposition length, SAL) were determined on the early post-EVAR CTA scan. NE, defined as the aortic diameter change between pre- and post-EVAR CTA scan, was determined at eight levels: +40, +30, +20, +15, +10, 0, -5 and -10 mm relative to the lowest renal artery baseline. The aortic neck diameter and preoperative oversizing were correlated to NE with the Pearson correlation coefficient. The effective post-EVAR endograft oversizing is calculated from the nominal endograft diameter and the post-EVAR neck diameter where the endograft is circumferentially apposed.

Results: The median time (interquartile range, IQR) between the EVAR procedure and the pre- and post-EVAR CTA scan was 40 (25, 71) days and 36 (30, 46) days, respectively. The Endurant II(s) endograft was deployed with a median (IQR) SFD of 1.0 (0.0, 3.0) mm. The SAL was <10 mm in 9% of patients and significantly influenced by the pre-EVAR aortic neck length (P=0.001), hostile neck shape (P=0.017), and maximum curvature at the suprarenal aorta (P=0.039). The median (interquartile range) SAL was 21.0 (15.0, 27.0) mm with a median (IQR) pre-EVAR infrarenal neck length of 23.5 (13.0, 34.8) mm. The median (IQR) difference between the SAL and neck length was -5.0 (-12.0, 2.8) mm. Significant (P<0.001) NE of 1.7 (0.9, 2.5) mm was observed 5 mm below the renal artery baseline, which resulted in an effective post-EVAR endograft oversizing <10% in 43% of the patients. No correlation was found between NE and aortic neck diameter or preoperative oversizing.

Conclusions: Circumferential apposition between an endograft and the infrarenal aortic neck, SAL, and NE can be derived from standard postoperative CT scans. These variables provide essential information about the post-procedural endograft and aortic neck morphology regardless of the preoperative measurements. Patients with SAL<10 mm or effective oversizing <10% due to NE may benefit from intensified follow-up, but clinical consequences of SAL and NE should be evaluated in future longitudinal studies with longer term follow-up.