An analysis of variables affecting aortic neck length with implications for fenestrated endovascular repair of abdominal aortic aneurysm.

A major factor in the selection of patients for endovascular aneurysm repair (EVAR) is the character of the aortic neck, and studies suggest that many patients are treated outside of the instructions for use (IFU) criteria. By analyzing aortic neck morphology, we hope to identify factors that may influence decision making about the use of fenestrated endografts as an alternative to extending the neck limitations of traditional endografts. A retrospective analysis was completed on 111 patients who underwent computed tomography angiography (CTA) scans between May 1, 2009 and January 3, 2011 for the evaluation of abdominal aortic aneurysm (AAA). Individual characteristics of neck and aneurysm morphology were analyzed to establish whether certain factors determined suitability for EVAR with traditional nonfenestrated endografts. In considering augmented neck lengths (ANL), anatomic measurements of distance from the start of aortic dilatation to the lowest renal artery (LRA) and highest renal artery (HRA) were analyzed. Measurements were analyzed using Stata software (version 11.2; StataCorp, College Station, TX). There were 86 men and 25 women in the patient population, with an average age of 72.9 years. In 46 patients, the proximal neck length was <15 mm, with 26 patients having neck lengths <10 mm. There was a negative relationship between AAA maximum diameter and proximal neck length (rs = -0.2237; P = 0.018), indicating that as aneurysm size increases, proximal neck length decreases. There was a significant correlation between proximal neck length and proximal neck diameter (rs = -0.2585; P = 0.006) and between proximal neck length and angle (rs = -0.2355; P = 0.013), and between proximal neck diameter and right iliac maximum diameter (rs = 0.2329; P = 0.014). Using fenestration to place an endograft above the LRA would create an ANL of >15 mm in 20 of 40 patients with aortic necks deemed too short to be eligible for EVAR using conventional infrarenal graft positioning. Extending the graft above the HRA would create an ANL of >15 mm in 36 of 40 patients. In this study, 41% of patients presented with neck lengths outside that of the traditional IFU for most aortic endografts. While there was wide variation from patient to patient, there was a general correlation between increasing AAA size and aneurysms that have shorter, wider, and more angulated proximal necks. Fenestration of even 1 renal artery could substantially increase the ANL. Additional study is warranted to determine if an increase in ANL in patients with otherwise short necks will positively impact long-term EVAR outcomes.

Stark M ，Suresh A ，Alexander J ，Cragg A ... -  《-》

The influence of gender and aortic aneurysm size on eligibility for endovascular abdominal aortic aneurysm repair.

The purpose of this study was to compare the eligibility of men and women with infrarenal abdominal aortic aneurysms (AAAs) for on-label endovascular aneurysm repair (EVAR) as part of the clinician-Food & Drug Administration (FDA) collaborative effort, the Characterization of Human Aortic Anatomy Project (CHAP). Computed tomography (CT) scans with 3D reconstruction from a single institution obtained between July 1996 and December 2009, including standardized measurements by a blinded third-party (M2S, West Lebanon, NH) were examined. For inclusion, abdominal aortic aneurysm (AAA) had to be infrarenal, unrepaired, and >5 cm, or 4 cm to 5 cm if the orthogonal sac diameter was more than twice the aortic diameter at the renal level. Scans were included regardless of subsequent EVAR, open repair, or lack of treatment. One thousand sixty-three unique, unrepaired AAAs were analyzed. Neck length, diameter, and angulation differ for women (P < .001) even after adjustment for patient age and AAA size. EVAR eligibility based on device Instructions for Use (IFU) criterion is affected by gender. Neck length <15 mm was found in 47% of men and 63% of women. Neck angulation exceeding 60 degrees was found in 12% of men and 26% of women. Minimum iliac diameter of 6 mm was found in 35% of men and 55% of women. Only 32% of men and 12% of women met all three neck criterion and had iliac lumen diameters >6 mm. Logistic regression modeling shows that older patient age (odds ratio [OR], 0.84 per decade), increased aneurysm diameter (OR, 0.70 per cm), and female gender (OR, 0.4) are each independently associated with decreased odds of meeting all device IFU neck criterion (P < .05). EVAR eligibility by neck criterion does not decline significantly until AAA size exceeds 5.5 cm in women and 6.5 cm in men. Women are significantly less likely to meet device IFU criterion for EVAR. Aortic neck criteria and iliac access are important for men and women, but more women than men fail to meet IFU criterion. Devices that accommodate shorter infrarenal AAA neck length will have the greatest impact on expanding on-label EVAR regardless of gender. Lower profile devices and those that accommodate higher neck angulation are expected to expand EVAR eligibility further for women. EVAR eligibility is unlikely to be lost as AAAs enlarge to 5.5 cm in women and 6.5 cm in men. Observation of small AAAs until they reach the standard threshold size for repair should not compromise EVAR eligibility.

Sweet MP ，Fillinger MF ，Morrison TM ，Abel D ... -  《-》

Anatomic feasibility of endovascular treatment of abdominal aortic aneurysms in emergency in the era of the chimney technique: impact on an emergency endovascular kit.

Despite promising results, endovascular aortic repair (EVAR) of ruptured/painful abdominal aortic aneurysms (RPAAA) continues to have limited use due to anatomic constraints linked to RPAAA morphology. Currently, EVAR for RPAAA is reserved for patients presenting with a long infrarenal aortic neck, because commercially available fenestrated stent grafts are not available in an emergency setting. Recently, the chimney technique (ChT) has been utilized to treat infrarenal abdominal aortic aneurysms (AAA) with short necks, but this technique requires specific materials. The aim of this study was to determine the rate of RPAAA eligible for EVAR since the advent of the ChT and to ascertain the standard materials needed in this context. We carried out a retrospective study of patients operated on for RPAAA (<24 hours after admission) at our center between 2006 and 2011. Patients' computed tomography (CT) scans were analyzed by two independent operators using 3-dimensional reconstruction software with a centerline of flow. To perform standard EVAR, the anatomic criteria used were those provided by the manufacturer (proximal neck diameter 18-32 mm with length >15 mm, angulation <60°, iliac diameter >7 mm). ChT anatomic feasibility criteria were: (1) a healthy aortic area >15 mm between the renal arteries and celiac trunk; (2) caudal orientation of renal arteries; and (3) a healthy descending thoracic aorta. Patients were classified according to the feasibility or nonfeasibility of standard EVAR and ChT. In total, over the period of study, 55 patients were operated on for RPAAA. In 5 patients (9%), CT scan quality was unsatisfactory and thus 50 patients (mean age 76 years, 75% men) were analyzed. Among them, 35 (70%) had a ruptured aneurysm and 17 (34%) were unstable. Anatomically, 22 (44%) patients were eligible for standard EVAR. Taking the ChT into consideration, an additional 11 (22%) patients were eligible for EVAR. Among these EVAR-eligible patients, mean proximal neck diameter was 23 ± 3 mm and stent grafts with 24-, 28-, and 32-mm diameters could fit in 33% (11 of 33), 51% (17 of 33), and 12% (4 of 33) of the cases, respectively. These results enabled us to determine the material that should be made available in the emergency setting in centers treating RPAAA. Among the 17 patients who were not eligible for EVAR, an iliac pathology (calcifications, stenosis) and a very hostile proximal neck (angulation, thrombus), respectively, were involved in 88% (15 of 17) and 12% (2 of 17) of the cases. The ChT increases EVAR feasibility by 50% in RPAAA. Taking into consideration our results, we recommend continued availability of emergency kits, including suitable aortouni-iliac stent grafts and basic material for performing ChT to allow surgeons to provide EVAR to the greatest number of RPAAA cases.

Brossier J ，Coscas R ，Capdevila C ，Kitzis M ，Coggia M ，Goeau-Brissonniere O ... -  《-》

Aortic neck enlargement after endovascular aneurysm repair using balloon-expandable versus self-expanding endografts.

This study evaluated changes in aortic neck diameter after endovascular aneurysm repair (EVAR) using a balloon-expandable stent (BES) endograft compared with a commercially available self-expanding stent (SES) endograft. We hypothesized that forces applied to the aortic neck by SES endografts may induce aortic neck enlargement over time and that such enlargement may not occur in aneurysm patients treated with a device that does not use a proximal SES. This was a retrospective quantitative computed tomography (CT) image analysis of patients treated with the Nellix (Endologix, Irvine, Calif) BES (n = 49) or the Endurant II (Medtronic, Minneapolis, Minn) SES (n = 56) endograft from 2008 to 2010. Patients with preimplant, postimplant, and at least 1-year serial CT scans underwent quantitative morphometric assessment by two independent vascular radiologists blinded to the outcome results. Changes in the infrarenal neck over time were compared with the suprarenal aorta for each patient. Follow-up extended to 4.8 years for the BES and to 4.6 years for the SES, with no significant difference in median follow-up time (34 months for BESs and 24 months for SESs; P = .06). There were no differences in preimplant neck diameter (25.2 ± 0.9 mm vs 25.7 ± 1.1 mm; P = .54) or length (27.7 ± 3.7 mm vs 23.6 ± 3.7 mm; P = .12) between BESs and SESs at baseline. After implantation, neck diameter increased by 1.1 ± 0.5 mm in BES patients and 2.6 ± 0.5 mm in SES patients (P = .07) compared with the preoperative diameter. At 3 years, neck diameter increased by 0.5 ± 0.9 mm in BES patients and by 3.8 ± 1.0 mm in SES patients (P = .0002) compared with the first postoperative CT scan. The annual postimplant rate of increase in the infrarenal neck diameter was fivefold greater in SES patients (1.1 ± 0.1 mm/y) than in BES patients (0.22 ± 0.04 mm/y; P < .0001). There were no significant differences in the diameter of the suprarenal aorta at baseline or at 3 years and no differences in the annual rate of change in suprarenal aortic diameter between BES and SES endografts. EVAR using SES endografts resulted in progressive infrarenal aortic neck enlargement, whereas EVAR using BES endografts resulted in no neck enlargement over time. These data suggest that infrarenal neck enlargement after EVAR with SES endografts is likely related to the force exerted by SES elements rather than disease progression in the infrarenal neck.

Savlovskis J ，Krievins D ，de Vries JP ，Holden A ，Kisis K ，Gedins M ，Ezite N ，Zarins CK ... -  《-》

Use of combined thoracic and abdominal endografts for proximal severe neck angulation in abdominal aortic aneurysms.

Silingardi R ，Lauricella A ，Tasselli S ，Trevisi Borsari G ，Mistral Klend Sasha N ，Coppi G ... -  《-》