Iliac Seal Zone Dynamics and Clinical Consequences After Endovascular Aneurysm Repair

Abstract

WHAT THIS PAPER ADDS Failure after EVAR is most often associated with loss of seal and consequent re-pressurisation of the aneurysm sac. This study explores the evolution of the iliac seal zones after implantation, showing that progressive dilatation and retraction are very common occurrences, which in turn have clinical consequences. Careful attention to planning to take full advantage of the potential iliac seal, avoidance of "bell-bottom" limbs whenever possible, and attention to signs of excessive dilatation and/or retraction over the course of follow-up are practical recommendations derived from the conclusions of this study that may improve outcomes.Objective: To evaluate the dynamics of the iliac attachment zone after EVAR, and the association with clinical events. Methods: A tertiary institution's prospective EVAR database was searched to identify common iliac arteries at risk. Internally validated measurements were made, using centre lumen line reconstructions. Iliac dilatation and endograft limb retraction were the main endpoints. Associations between dilatation, retraction, oversizing, and distal seal length were investigated. Association with clinical events (sealing or occlusion) was also explored. Results: Of 452 primary EVAR patients treated from 2004 to 2012, 341 were included (mean age 72 years, 12% female, 597 common iliac arteries). Median follow-up was 4.7 years. At 30 days, the mean iliac diameter increased from 14 mm to 15 mm (p < .001). Over follow-up, it increased to 18 mm (p < .001). Iliac dilatation !20% occurred in 295 cases (49.4%) and exceeded the implanted endograft diameter in 170 (28.7%). Limb retraction !5 mm was identified in 54 patients (9.1%) and was associated with iliac seal complications (p < 0.001). Iliac endograft extension diameter !24 mm (OR 3.3, 95% CI 1.7e6.4) and iliac artery dilatation beyond the endograft (OR 2.1, 95% CI 1.2e3.8) were independent risk factors. Overall, there were 34 (5.7%) iliac seal complications. Retraction of the iliac endograft (OR 1.17 per mm, 95% CI 1.10e1.24) and baseline AAA diameter (1.04 per mm, 95% CI 1.01e1.07) were independent risk factors for seal related complications. Greater initial post-operative iliac seal length was protective (OR 0.94 per mm, 95% CI 0.90e0.97). Conclusions: Iliac dilatation and endograft retraction are common findings during follow-up, potentially leading to adverse clinical events. Optimisation of the iliac seal zone providing a long distal seal length and added attention to patients with large aneurysms or receiving !24 mm diameter iliac extensions are recommended. Also, long-term surveillance including CTA is advised to reveal and correct loss of seal at the iliac attachments before adverse clinical events occur. Ó

A systematic review of standardized methods for assessment of endograft sealing on computed tomography angiography post-endovascular aortic repair, and its influence on endograft-associated complications

“…After the 23 full-text papers were read for eligibility, 10 additional studies were removed because eight studies did not include measurement of endograft position relative to an anatomical landmark or endograft apposition with the arterial vessel wall, one study measured these parameters from 2D digital subtraction angiography images, and one study reported measurements on fewer than 10 patients. The remaining 13 studies were included in this review [4][5][6][7][8][13][14][15][16][17][18][19][20]. A flowchart of the selection procedure is shown in Figure 1.…”

“…Quantitative analysis was not performed because of the heterogeneity of study design, patient inclusion, end points, follow-up, and measurement methods. Five studies assessed the endograft in the proximal landing zone in the aortic neck after EVAR [8,14,17,19,20], three studies assessed the distal landing zone in the common iliac arteries (CIAs) after EVAR [6,7,16], and three studies assessed proximal and distal landing zones [4,5,15]. One study assessed the proximal landing zone after TEVAR [13], and one assessed the distal landing zone after TEVAR [18].…”

“…The method has been used for the determination of apposition and position of the endograft within the artery and requires a dedicated vascular workstation that facilitates a centerline reconstruction with orthogonal planes. Precision of the measurements has only been validated for the distance between the distal edge of the endograft limb and the iliac artery bifurcation [7]. The method has been used to assess proximal endograft apposition in the aortic neck [4,5,14,15,19], proximal endograft position in the aortic neck relative to the lowest renal artery [4,5] or relative to the superior mesenteric artery (SMA) [15], distal endograft apposition in the CIAs [4][5][6][7]15,16], distal endograft limb position in the CIAs relative to the iliac bifurcation [6,7,15,16], proximal position of the thoracic endograft relative to the left subclavian artery (LSA) [13], and distal position of the thoracic endograft relative to the celiac trunk [18].…”

“…Risk of bias for selection was low (mean score, 3.7 of 4) but was high for comparability (mean score, 0.7 of 2) and for outcome (mean score, 1.3 of 3). Seven studies were designed to compare patients with endograft-associated complications, AAA-associated complications, or re-intervention to controls with endograft apposition or position as an end point (Supplementary Table 2) [4,[6][7][8]13,15,19]. Risk of bias for selection was low (mean score, 3.6 of 4) but high for comparability (0.3 of 2) and moderate for exposure (1.6 of 3).…”

“…However, the three-dimensional (3D) CTA volumes contain much more valuable information in addition to sensitive detection of aneurysm growth and endoleaks, which are currently seldom used and not detectible on duplex ultrasound or x-ray imaging. Accurate measurement of the endograft position relative to anatomical landmarks and proximal and distal endograft apposition with the arterial wall on the first postoperative CTA scan can stratify the patient's risk for future complications [4][5][6][7]. Comparing these endograft properties during follow-up reveals subtle changes that may precede later complications [8].…”