Abdominal aortic aneurysm neck dilatation and sac remodeling in fenestrated compared to standard endovascular aortic repair

Abstract

Objective

Contemporary commercially available endovascular devices for the treatment of abdominal aortic aneurysm (AAA) include standard endovascular aortic repair (sEVAR) or fenestrated EVAR (fEVAR) endografts. However, aortic neck dilatation (AND) can occur in nearly 25% of patients following EVAR, resulting in loss of proximal seal with risk of aortic rupture. AND has not been well characterized in fEVAR, and direct comparisons studying AND between fEVAR and sEVAR have not been performed. This study aims to analyze AND in the infrarenal and suprarenal aortic segments, including seal zone, and quantify sac regression following fEVAR implantation compared to sEVAR.

Method

A retrospective review of prospectively collected data on 20 consecutive fEVAR patients (Cook Zenith® Fenestrated) and 20 sEVAR (Cook Zenith®) patients was performed. Demographic data, anatomic characteristics, procedural details, and clinical outcome were analyzed. Pre-operative, post-operative (1 month), and longest follow-up CT scan at an average of 29.3 months for fEVAR and 29.8 months for sEVAR were analyzed using a dedicated 3D workstation (iNtuition, TeraRecon Inc, Foster City, California). Abdominal aortic aneurysm neck diameter was measured in 5 mm increments, ranging from 20 mm above to 20 mm below the lowest renal artery. Sub-analysis comparing the fEVAR to the sEVAR group at 12 months and at greater than 30 months was performed. Standard statistical analysis was done.

Results

Demographic characteristics did not differ significantly between the two cohorts. The fEVAR group had a larger mean aortic diameter at the lowest renal artery, shorter infrarenal aortic neck length, increased prevalence of nonparallel neck shape, and longer AAA length. On follow-up imaging, the suprarenal aortic segment dilated significantly more at all locations in the fEVAR cohort, whereas the infrarenal aortic neck segment dilated significantly less compared to the sEVAR group. Compared to the sEVAR cohort, the fEVAR patients demonstrated significantly greater positive sac remodeling as evident by more sac diameter regression, and elongation of distance measured from the celiac axis to the most cephalad margin of the sac. Device migration, endoleak occurrence, re-intervention rate, and mortalities were similar in both groups.

Conclusion

Compared to sEVAR, patients undergoing fEVAR had greater extent of suprarenal AND, consistent with a more diseased native proximal aorta. However, the infrarenal neck, which is shorter and also more diseased in fEVAR patients, appears more stable in the post-operative period as compared to sEVAR. Moreover, the fEVAR cohort had significantly greater sac shrinkage and improved aortic remodeling. The suprarenal seal zone in fEVAR may result in a previously undescribed increased level of protection against infrarenal neck dilatation. We hypothesize that the resultant decreased endotension conferred by better seal zone may be responsible for a more dramatic sac shrinkage in fEVAR.

Keywords

Abdominal aortic aneurysm endovascular aortic repair fenestrated aortic neck sac remodeling

Introduction

The overall pooled prevalence of abdominal aortic aneurysm (AAA) is 4.8% in the general population,¹ and contemporary commercially available treatment options for AAA encompass standard endovascular aortic repair (sEVAR) as well as fenestrated EVAR (fEVAR), for juxtarenal AAA with short infrarenal seal zones.² Indeed, important criteria for EVAR planning are the quality of the aortic neck, critical for proper sealing of the AAA after endograft implantation.^2–4 However, as many as 25% of sEVAR patients have been observed to have aortic neck dilatation (AND) during follow-up, and this is correlated with adverse outcomes.⁴ In some cases, AND may lead to loss of sealing and fixation of the endograft, resulting in type 1a endoleak and device migration.^4–6 AND has not been well characterized in fEVAR, and moreover, a comparison of the degree and location of AND between fEVAR and sEVAR has not been performed. This study aims to analyze the extent of AND in infrarenal and suprarenal segments after fEVAR compared to sEVAR using the Cook Zenith platform for EVAR and fEVAR.

Materials and Methods

General Information

This study was approved by the ethical committee and the institutional review board of New York University Langone Health, and rules according to the Helsinki Declaration were followed. Given that this is a retrospective review of prospectively collected data, informed consents were waived by the institutional review board. From 2013 to 2019, 76 patients with AAA were treated with fEVAR and 213 patients were treated with sEVAR. Indications for repair such as diameter, growth rate >5 mm over 6 months, symptomatic status, and concurrent iliac aneurysm were based on discretion of the treating physician. Instructions for use from the manufacturer were followed, specifically with fEVAR used for patients with short infrarenal aortic neck of at least 4 mm, and sEVAR for those with neck 15 mm or greater. Parallel branch EVAR or physican-modified EVAR cases were excluded. Only patients with available pre-operative, 1-month post-operative, and minimum 1-year follow-up computer tomography angiogram (CTA) were included in this study. Twenty consecutive patients meeting the above inclusion criteria treated using fEVAR (Zenith® Fenestrated endograft, Cook, Bloomington, Indiana) were compared to 20 consecutive patients treated using sEVAR (Zenith® endograft, Cook, Bloomington, Indiana).

Variables and Outcomes

Pre-operative, 1-month post-operative, and the longest available follow-up CTA at an average of 29.3 months for fEVAR and 29.8 months for sEVAR were analyzed using a dedicated 3D workstation (iNtuition, TeraRecon Inc, Foster City, California). Baseline demographic and radiographic characteristics, procedural details, and clinical outcomes were abstracted and analyzed. The primary outcome was changed in suprarenal and infrarenal aortic neck dilatation, as well as the change in the maximum sac diameter in the fEVAR group and the sEVAR group over time. Similar to other authors who have studied aortic neck dilatation following EVAR, we chose to use the 1-month post-operative CTA as baseline measurement for aortic neck in all patients. In this manner, we are able to standardize measurements and avoid inconsistencies which can occur when measuring native aorta at various points in the cardiac cycle. A sub-analysis was performed comparing patients with CTA at 12 months, and at greater than 30 months, who underwent fEVAR versus sEVAR. The aortic neck and the para-renal aorta were mapped and analyzed in 5 mm increments, ranging from 20 mm above to 20 mm below the lowest renal artery reference point (Figure 1). Secondary radiographic outcomes included changes over time in the distance between celiac artery to the proximal extent of the aneurysm, a surrogate for sac remodeling, as well as celiac artery to the top of graft fabric, an estimate for graft migration. Secondary clinical outcomes included type 1a endoleak and type 2 endoleak, branch vessel occlusion, device-related re-intervention, aortic-related mortality, and all-cause mortality.

Figure 1.

Graphic representation of mapping of the infrarenal neck and the para-renal aorta. 5 mm increments were measured and compared with respect to the lowest renal artery, under centerline analysis.

Infrarenal aortic neck length, morphology, degree of thrombus, and calcification were assessed based on the pre-operative CTA. Nonparallel neck shape was defined as change in neck diameter >10% in proximal landing zone. Severe neck thrombus was defined as circumferential thrombus or greatest thickness of 5 mm or greater. Severe neck calcification was defined as circumferential calcification or greatest thickness of 3 mm or greater. Mean device oversizing was calculated from (device diameter - average proximal landing zone diameter)/average proximal landing zone diameter, using the pre-operative CTA.

Statistical Analysis

All diameters and lengths were presented as percent change over time; this was caculated by taking the absolute difference between the follow-up CTA measurement and the 1-month (baseline) post-operative CTA measurement, and dividing this by the 1-month post-operative CTA measurement. The average absolute changes in diameter or distance were also measured. The difference in categorical variables and frequencies between the fEVAR and sEVAR groups was analyzed using Fisher’s exact test. Difference in continuous variables between the two groups was analyzed using Student’s T test. Difference was considered as statistically significant for p values < 0.05 (two sided). Statistical analyses were performed by using SPSS software (version 25.0, IBM Corp, Armonk, NY).

Results

Table 1 shows the baseline demographics and radiographic data between the fEVAR and the sEVAR cohort. The fEVAR group had significantly larger aortic diameter at the lowest renal artery (29.2 ± 7.19 vs 24.6 ± 2.94 mm, p = 0.012) and a shorter infrarenal neck length (6.65 ± 5.04 vs 35.32 ± 14.77 mm, p < 0.001). Differences in mean device diameter, mean device oversizing, and the length of proximal sealing measured from top of the graft fabric to the lowest margin of the infrarenal neck did not reach statistical significance. Frequency of nonparallel neck shape was greater in the fEVAR group (85% vs 50%, p = 0.041), whereas other surrogates for hostile neck such as severe neck thrombus or calcification were not significantly different between the two cohorts. AAA length was significantly longer in the fEVAR group (97.12 ± 27.51 vs 73.96 ± 18.43 mm, p = 0.003), presumably from a more proximal AAA extent, whereas AAA maximum diameter was similar between the two groups.

Table 1.

Demographics and baseline radiographic data.

	fEVAR	EVAR	p value
Number of patients	20	20	1.000
Longest CT follow-up (month)	29.3 ± 16.1	29.8 ± 16.1	0.922
Age at procedure (years)	75.4 ± 9.67	75.35 ± 7.07	0.985
Male (%)	85	100	0.231
CAD (%)	55	50	1.000
COPD (%)	25	10	0.407
DM (%)	10	25	0.407
HTN (%)	80	80	1.000
Active smoker (%)	25	10	0.407
Pre-op creatinine (mg/dL)	1.06 ± 0.19	1.07 ± 0.22	0.880
Diameter at lowest renal (mm)	29.2 ± 7.19	24.6 ± 2.94	0.012
Infrarenal neck length (mm)	6.65 ± 5.04	35.32 ± 14.77	<0.001
Mean device diameter (mm)	30.1 ± 3.7	28.1 ± 3.8	0.098
Mean device oversizing (%)	11.6	14.3	0.354
Length of proximal sealing (mm)	33.37 ± 9.45	31.21 ± 9.19	0.496
Nonparallel neck shape (%)	85	50	0.041
Severe neck thrombus (%)	20	10	0.661
Severe neck calcification (%)	5	5	1.000
AAA max diameter (mm)	60.44 ± 10.23	58.95 ± 11.09	0.662
AAA length (mm)	97.12 ± 27.51	73.96 ± 18.43	0.003

Demographic and baseline radiographic data between fEVAR and sEVAR group. CAD: coronary artery disease; COPD: chronic obstructive pulmonary disease; DM: diabetes mellitus; HTN: hypertension; AAA: abdominal aortic aneurysm.

Table 2 shows the radiographic changes, as well as clinical outcomes between the fEVAR and the sEVAR groups. Nearly all of the suprarenal aortic segments dilated significantly more in the fEVAR group compared to the sEVAR group (p < 0.05). On the contrary, the infrarenal aortic neck segments dilated significantly less in the fEVAR group compared to the sEVAR group. The fEVAR group demonstrated greater sac regression and remodeling, as evident by the decrease in maximum sac diameter (−15.7% vs −4.9%, p = 0.04), and the increase in the distance from the celiac axis to the most cephalad margin of the sac (29.9% vs 3.4%, p = 0.017). The distance from celiac artery to the top of graft fabric, a surrogate for device migration, did not differ between the two groups. 30% of the sEVAR group had two consecutive segments that dilated beyond the stent graft diameter, whereas this was found in 50% of the fEVAR cohort. Clinical outcomes such as type 1a or type 2 endoleak occurrence, device-related re-intervention, and mortality were similar in both groups, at an average of 29.3 and 29.8 months of follow-up, respectively.

Table 2.

Radiographic and clinical outcome in fEVAR versus sEVAR.

% of Diameter changes (absolute change in mm)	fEVAR (N = 20)	sEVAR (N = 20)	p value
CA	4 (1.2±1.9)	2 (0.58 ± 1.1)	0.22
SMA	9 (2.5 ± 1.7)	3.5 (0.93 ± 1.9)	0.009
+20 mm	9.9 (2.6 ± 1.8)	2.7 (0.70 ± 1.3)	<0.001
+15 mm	9.9 (2.6 ± 1.9)	2.3 (0.60 ± 1.7)	0.001
+10 mm	12.4 (3.3 ± 1.5)	6.2 (1.6 ± 1.6)	0.002
+5 mm	13.1 (3.5 ± 1.5)	5.9 (1.5 ± 1.9)	0.002
Lowest renal	10.4 (2.1 ± 6.4)	5.9 (1.4 ± 1.9)	0.26
−5 mm	9.9 (2.3 ± 4.8)	11.1 (2.5 ± 2.1)	0.77
−10 mm	6.7 (1.4 ± 4.7)	12.9 (3.0 ± 2.7)	0.13
−15 mm	1.7 (−0.03 ± 4.5)	14.3 (3.5 ± 2.3)	<0.001
−20 mm	2.1 (−0.02 ± 5.6)	16.6 (4.2 ± 3.4)	0.03
Sac max diameter	−15.7 (−9.0 ± 12.0)	−4.9 (−3.2 ± 7.7)	0.04
% Of distance changes (Absolute change in mm)
CA to sac	29.9 (15.5 ± 25.2)	3.4 (2.5 ± 8.4)	0.017
CA to TOG	11.7 (1.8 ± 2.9)	13.4 (4.0 ± 6.3)	0.85
Clinical outcomes (%)
Consecutive segments dilated beyond device diameter	30	50	0.333
Type 1a/3 endoleak	0	0	N/A
Type 2 endoleak	35	45	0.748
Branch vessel occlusion	0	0	N/A
Device-related re-intervention	10	5	1.000
All-cause mortality	10	15	1.000
Aortic-related mortality	0	0	N/A

Radiographic and clinical outcome between fEVAR and sEVAR group. The latest follow CT scan is compared to the first post-operative CT scan using dedicated workstation (iNtuition, TeraRecon Inc, Foster City, Calif). CA: celiac axis; MA: superior mesenteric artery; TOG: top of graft.

Similar to the finding from the total cohort in each group, this sub-analysis at each time point of 12 months and greater than 30 months further confirmed the phenomenon that the suprarenal segments in the fEVAR group had more significant dilatation compared to the sEVAR group. Similarly, the infrarenal regions in the fEVAR group appear to dilate less compared to the sEVAR group. In the subgroup analysis, the sac diameter change did not reach statistical significance at 12 or >30 months, but trended to have greater shrinkage in the fEVAR group (Table 3). The aforementioned neck diameter changes became pronounced at follow-up CTA >30 months compared to those at 12 months

Table 3.

Radiographic change in fEVAR versus sEVAR at 12 and >30 months.

% of diameter changes (absolute change in mm)	fEVAR (N = 9) at 12.3 ± 1.7 months	sEVAR (N = 10) at 13.9 ± 3.4 months	p value	fEVAR (N = 12) at 38.2 ± 14.4 months	sEVAR (N=9) at 40.8 ± 10.4 months	p value
CA	−0.2 (−0.1 ± 1.1)	0.3 (0.12 ± 0.8)	0.757	4.4 (1.2 ± 1.6)	2.2 (0.66 ± 1.3)	0.354
SMA	5.7 (1.5 ± 1.2)	1.4 (0.39 ± 1.1)	0.044	9.7 (2.6 ± 1.5)	2.1 (0.61 ± 1.8)	0.012
+20 mm	3.8 (1.0 ± 0.94)	2.5 (0.66 ± 0.78)	0.373	12.3 (3.1 ± 1.7)	4.2 (1.1 ± 1.6)	0.017
+15 mm	4.6 (1.2 ± 1.8)	2.7 (0.66 ± 1.7)	0.503	11.5 (3.0 ± 1.3)	4.6 (1.2 ± 1.3)	0.007
+10 mm	8.0 (2.1 ± 1.5)	5.1 (1.4 ± 1.0)	0.215	13.4 (3.6 ± 1.1)	8.5 (2.2 ± 1.8)	0.055
+5 mm	6.8 (1.9 ± 1.5)	1.7 (0.47 ± 1.1)	0.030	14.2 (3.7 ± 1.5)	8.6 (2.1 ± 1.8)	0.090
Lowest renal	1.4 (−1.0 ± 8.4)	1.5 (0.37 ± 1.7)	0.988	14.6 (3.8 ± 1.5)	9.5 (2.3 ± 2.1)	0.137
-5 mm	1.2 (−0.52±4.3)	6.3 (1.6 ± 2.4)	0.320	16.2 (4.2 ± 3.6)	12.6 (2.9 ± 2.0)	0.486
−10 mm	1.5 (0.59 ± 5.0)	5.3 (1.3 ± 1.5)	0.436	10.1 (2.8 ± 3.7)	17.9 (4.2 ± 2.3)	0.152
−15 mm	1.1 (−0.71 ± 3.7)	8.5 (2.1 ± 2.1)	0.098	3.3 (0.9 ± 4.4)	19.0 (4.6 ± 2.1)	0.006
−20 mm	−0.4 (−1.1 ± 4.6)	8.6 (2.2 ± 2.1)	0.070	1.9 (0.55 ± 5.3)	17.8 (4.5 ± 4.6)	0.039
Sac max diameter	−8.8 (−5.3 ± 5.2)	−3.4 (−2.9 ± 6.5)	0.197	−16.6 (−9.5 ± 15.1)	−5.4 (−3.1 ± 8.6)	0.242
CA to TOG	−1.1 (0.23 ± 2.0)	15.8 (4.0 ± 7.3)	0.227	18.2 (2.2 ± 2.3)	4.7 (2.0 ± 4.0)	0.146

Radiographic measurements between fEVAR and sEVAR group at 12 months follow-up and at more than 30 months follow-up, compared to the first post-operative CT scan. Of note, the 12 months and >30 months group do not contain all of the same patients, as some had follow-up CT at 12 months but not >30 months, or vice versa. Both the percentage of change from the baseline measurements and the absolute change in parenthesis are presented.

Discussion

AND has been described following both endovascular and open repair of AAA.^7,8 In sEVAR, proposed risk factors for AND include large or unfavorable aortic neck, use of self-expanding stent grafts, and excessive device oversizing.^9–12 A meta-analysis by Kouvelos et al.⁴ showed that AND can occur in up to 25% of patients undergoing sEVAR, and is associated with adverse outcomes such as type 1a endoleak, device migration, and re-intervention. Others have also shown that AND is associated with device migration, re-intervention, and late type 1a endoleak.^13–15 However, there are only a few studies on AND in fEVAR alone, and no direct comparison exists between fEVAR and sEVAR with respect to AND and its effect on sac remodeling. A study by Qaderi and collegues on physician-modified endografts showed that AND was not associated with adverse outcomes, and that these devices dilated to their nominal diameter and not beyond.¹⁶ Similarly, Tran et al.¹⁷ have studied AND in 43 patients who underwent fEVAR using commercially available devices and shown significant dilatation of the suprarenal aorta which was not associated with endoleak. Notably, the latter study mapped the seal zone according to the fEVAR sealing stents, whereas in our study we chose to examine the native aorta relative to the lowest renal artery, the most commonly accepted reference point for proximal seal. In this manner, we are focusing on the anatomy of the seal zone itself versus the location of the stent graft. In addition, measuring aortic dilatation based on sealing stents may be problematic in the setting of stent migration and aortic remodeling.

In this study, we found that the suprarenal aorta dilated significantly more, whereas the infrarenal segment dilated significantly less in the fEVAR group compared to the sEVAR group. This finding was true when comparing the overall cohorts, as well as in the sub-analysis segregating the scohort into those with 12 months follow-up CTA and with greater than 30 months follow-up CTA. Presumably, the fEVAR group had more diseased and aneurysmal para-renal and para-visceral aorta compared to the sEVAR, which may explain the more significant suprarenal AND over time, suggesting a chronic degenerative process intrinsic to the diseased aortic wall. A significant proportion of patients in both the sEVAR and the fEVAR groups had two consecutive aortic segments that dilated beyond the stent graft diameter, suggesting that aortic degeneration, in addition to stent graft radial force from oversizing, may contribute to AND. AND also became more pronounced at greater than 30 months, indicating that it is a chronic process, again indicating that a mechanism intrinsic to the aneurysmal degeneration might be contributing.

Moreover, fEVAR induced more sac regression compared sEVAR in this analysis, despite having similar device oversizing and length of sealing, and having larger diameter at the level of the lowest renal artery, shorter infrarenal neck length, higher frequency of nonparallel neck shape, and longer AAA length. Others have also demonstrated positive sac remodeling in fEVAR: one group showed that the mean aneurysm sac diameter decreased from 60.2 ± 9.3 mm pre-operatively to 53.2 ± 12.8 mm at mean follow-up of 21 ± 15.9 months (p < 0.001) with repair using Cook Zenith Fenestrated Endograft.¹⁸ fEVAR with Anaconda demonstrated 94% sac regression or stabilization at short–medium term follow-up.¹⁹ Tran et al.¹⁷ observed that 72% of fEVAR patients demonstrated >5 mm sac shrinkage in their midterm follow-up. Our study adds to the existing literature by comparing and quantifying the AND and sac remodeling in fEVAR compared to sEVAR and further suggests an inverse relationship between infrarenal AND and sac shrinkage in fEVAR. It has been shown that sac regression may correlate with decreased adverse events and mortality in both fEVAR and sEVAR.^20,21

There were no differences in clinical outcomes such as type 1a or type 2 endoleak occurrence, device-related re-intervention, and aortic-related or all-cause mortalities between the fEVAR and the sEVAR group, although our study was not powered to detect differences in these secondary endpoints. Others have shown an association between infrarenal AND and type 1a endoleak, migration, and re-intervention; however, the impact of suprarenal AND on clinical outcome has not been thoroughly investigated.^4,17 It is worth noting that by taking the seal to the para-renal and para-visceral level, the fEVAR cohort in this investigation achieved no type 1a or 3 endoleak and comparable clinical outcomes to the sEVAR group that altogether had a more favorable aortic anatomy for endovascular repair. Other studies on fEVAR and physician modified endografts also support the protective effects of the longer seal zones on AND and subsequent clinical outcome.^16,17

This study is limited by its retrospective design; therefore, the conclusion is hypothesis-generating only. The sample size is limited to detect and quantify aortic neck morphological changes in fEVAR compared to sEVAR, and was insufficient to detect clinical outcome differences. All of the measurements were taken by a single investigator on centerline mode; although this created consistency across the whole dataset, inter-observer differences were not accounted for. Despite having sealing stents at different locations in fEVAR and sEVAR, we chose to map the aortic neck with respect to the aorta itself instead of the sealing stents from the endograft, as we hypothesize that AND, especially in the long term is largely attributed by the aortic disease itself instead of the radial force from the stent graft. This approach at quantifying AND is unique to this study, whereas others attempted to quantify based on the stent graft instead.¹⁷ Our average follow-up imaging was limited to 30 months and may under-appreciate more delayed AND which others have shown may appear after 3 years²² Not every patient had consistent annual CT scans; therefore, year-by-year comparison in neck and aneurysmal changes and Kaplan–Meier analysis were not performed. This study only included devices from Cook Medical, and did not investigate AND in standard or fenestrated devices from other manufacturers.

Conclusion

Compared to sEVAR, patients undergoing fEVAR had greater extent of suprarenal AND, consistent with a more diseased native proximal aorta. However, the infrarenal neck, which is shorter and also more diseased in fEVAR patients, appears more stable in the post-operative period as compared to sEVAR cases. Moreover, the fEVAR cohort had significantly greater sac shrinkage and improved sac remodeling. The suprarenal seal zone in fEVAR may confer a previously undescribed increased level of protection against infrarenal neck dilatation and lessen endotension, resulting in more dramatic sac shrinkage. AND should be studied in a larger cohort with consistent imaging intervals and longer follow-up in order to better understand its effect on durability of standard and fenestrated EVAR devices.

Footnotes

Declaration of conflicting interests

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: TSM, NC and KG are consultants for Cook Medical. The other authors have no conflict of interest to disclose.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Chong Li

Karan Garg

References

Zhao

Zhang

, et al. Prevalence and trends of the abdominal aortic aneurysms epidemic in general population--a meta-analysis. PLoS One 2013; 8(12): e81260.

Schanzer

Greenberg

Hevelone

, et al. Predictors of abdominal aortic aneurysm sac enlargement after endovascular repair. Circulation 2011; 123: 2848–2855.

Leurs

Kievit

Dagnelie

EUROSTAR Collaborators , et al. Influence of infrarenal neck length on outcome of endovascular abdominal aortic aneurysm repair. J Endovasc Ther 2006; 13: 640–648.

Kouvelos

Oikonomou

Antoniou

, et al. A systematic review of proximal neck dilatation after endovascular repair for abdominal aortic aneurysm. J Endovasc Ther 2017 Feb; 24(1): 59–67.

Pintoux

Chaillou

Azema

, et al. Long-term influence of suprarenal or infrarenal fixation on proximal neck dilatation and stentgraft migration after EVAR. Ann Vasc Surg 2011 Nov; 25(8): 1012–1019.

Oberhuber

Schwarz

Hoffmann

, et al. Influence of fixation mechanism on changes of the supra- and infrarenal segment of the aorta after endovascular treatment of infrarenal aortic aneurysm. Zentralbl Chir 2010; 135: 433–437.

Brewster

Jones

Chung

, et al. Long-term outcomes after endovascular abdominal aortic aneurysm repair: the first decade. Ann Surg 2006; 244: 426–438.

Oberhuber

Buecken

Hoffmann

, et al. Comparison of aortic neck dilatation after open and endovascular repair of abdominal aortic aneurysm. J Vasc Surg 2012 Apr; 55(4): 929–934.

Oliveira

NFG

Oliveira-Pinto

van Rijn

, et al. Risk factors, dynamics, and clinical consequences of aortic neck dilatation after standard endovascular aneurysm repair. Eur J Vasc Endovasc Surg 2021 Jun 2; 62(1): 26–35.

10.

De Donato

Setacci

Bresadola

, et al. Aortic neck evolution after endovascular repair with TriVascular Ovation stent graft. J Vasc Surg 2016; 63: 8–15.

11.

Kret

Tran

Lee

. Change in aortic neck diameter after endovascular aortic aneurysm repair. Ann Vasc Surg 2017 Aug; 43: 115–120.

12.

Monahan

T.S.

Chuter

T.A.

Reilly

L.M.

, et al. Long-term follow-up of neck expansion after endovascular aortic aneurysm repair. J Vasc Surg 2010; 52: 303–307.

13.

Napoli

Sardella

Bargellini

, et al. Evaluation of the proximal aortic neck enlargement following endovascular repair of abdominal aortic aneurysm: 3-years experience. Eur Radiol 2003; 13: 1962–1971.

14.

Cao

Verzini

Parlani

, et al. Predictive factors and clinical consequences of proximal aortic neck dilatation in 230 patients undergoing abdominal aorta aneurysm repair with self-expandable stent-grafts. J Vasc Surg 2003; 37: 1200–1205.

15.

Dillavou

Muluk

Makaroun

. Is neck dilatation after endovascular aneurysm repair graft dependent? Vasc Endovasc Surg 2005; 39: 47–54.

16.

Qaderi

Tran

Tatum

, et al. Aortic neck dilation is not associated with adverse outcomes after fenestrated endovascular aneurysm repair: Midterm results from an investigational device exemption clinical trial. J Vasc Surg 2018 Oct 6 69(4): 1059–1065.

17.

Tran

Deslarzes-Dubuis

Lee

. Quantification of suprarenal aortic neck dilation after fenestrated endovascular aneurysm repair. J Vasc Surg 2021 Jan; 73(1): 31–38.

18.

Verhoeven

Katsargyris

Oikonomou

, et al. Fenestrated endovascular aortic aneurysm repair as a first line treatment option to treat short necked, juxtarenal, and suprarenal aneurysms. Eur J Vasc Endovasc Surg 2016 Jun; 51(6): 775–781.

19.

Kotelis

Schleimer

Foldenauer

, et al. Operative and midterm outcomes of the fenestrated Anaconda stent-graft in the endovascular treatment of juxtarenal, suprarenal, and type IV thoracoabdominal aortic aneurysms. J Endovasc Ther 2016 Dec; 23(6): 930–935.

20.

Stern

Tran

, et al. Predictors of sac regression and mortality after fenestrated endovascular aneurysm repair. J Vasc Surg 2020 Sept; 72(3): e323–e324.

21.

O’Donnell

TFX

Deery

Boitano

, et al. Aneurysm sac failure to regress after endovascular aneurysm repair is associated with lower long-term survival. J Vasc Surg 2019 Feb; 69(2): 414–422.

22.

Tsilimparis

Dayama

Ricotta

. Remodeling of aortic aneurysm and aortic neck on mid- and long-term follow-up after endovascular repair with suprarenal fixation. J Vasc Surg 2011; 55(6): 96S.