Predicting Infection Related Complications After Endovascular Repair of Infective Native Aortic Aneurysms.

OBJECTIVE: Endovascular aortic repair (EVAR) as surgical treatment for infective native aortic aneurysm (INAA) is associated with superior survival compared with open surgery, but with the risk of infection related complications (IRCs). This study aimed to assess the association between baseline clinical and computed tomography (CT) features and the risk of post-operative IRCs in patients treated with EVAR for INAA. It also sought to develop a model to predict long term IRCs in patients with abdominal INAA treated with EVAR. METHODS: All initial clinical details and CT examinations of INAAs between 2005 and 2020 at a major referral hospital were reviewed retrospectively. The images were scrutinised according to aneurysm features, as well as peri-aortic and surrounding organ involvement. Data on post-operative IRCs were found in the patient records. Cox regression analysis was used to derive predictors for IRCs and develop a model to predict five year IRCs after EVAR in abdominal INAA. RESULTS: Of 3 780 patients with the diagnosis of aortic aneurysm or aortitis, 98 (3%) patients were treated with EVAR for abdominal INAAs and were thus included. The mean follow up time was 52 months (range 0 ‒ 163). The mean transaxial diameter was 6.5 ± 2.4 cm (range 2.1 ‒14.7). In the enrolled patients, 38 (39%) presented with rupture. The five year IRC rate in abdominal INAAs was 26%. Female sex, renal insufficiency, positive blood culture, aneurysm diameter, and psoas muscle involvement were predictive of five year IRC in abdominal INAA after EVAR. The model had a C-index of 0.76 (95% CI 0.66 - 0.87). CONCLUSION: Pre-operative clinical and CT features have the potential to predict IRC after endovascular aortic repair in INAA patients. These findings stress the importance of rigorous clinical, laboratory, and radiological follow up in these patients.

Features of infective native aortic aneurysms on computed tomography.

BACKGROUND: Infective native aortic aneurysm (INAA) is a rare clinical diagnosis. The purpose of this study was to describe the CT findings of INAAs in detail. METHODS: This was a retrospective single-center study of INAA patients at a major referral hospital between 2005 and 2020. All images were reviewed according to a protocol consisting of aneurysm features, periaortic findings, and associated surrounding structures. RESULTS: One hundred and fourteen patients (mean age, 66 years [standard deviation, 11 years]; 91 men) with 132 aneurysms were included. The most common locations were infrarenal (50.8%), aortoiliac (15.2%), and juxtarenal (12.9%). The mean transaxial diameter was 6.2 cm. Most INAAs were saccular (87.9%) and multilobulated (91.7%). Calcified aortic plaque was present in 93.2% and within the aneurysm in 51.5%. INAA instability was classified as contained rupture (27.3%), impending rupture (26.5%), and free rupture (3.8%). Rapid expansion was demonstrated in 13 of 14 (92.9%) aneurysms with sequential CT studies. Periaortic inflammation was demonstrated as periaortic enhancement (94.7%), fat stranding (93.9%), soft-tissue mass (92.4%), and lymphadenopathy (62.1%). Surrounding involvement included psoas muscle (17.8%), spondylitis (11.4%), and perinephric region (2.8%). Twelve patients demonstrated thoracic and abdominal INAA complications: fistulas to the esophagus (20%), bronchus (16%), bowel (1.9%), and inferior vena cava (IVC) (0.9%). CONCLUSION: The most common CT features of INAA were saccular aneurysm, multilobulation, and calcified plaques. The most frequent periaortic findings were enhancement, fat stranding, and soft-tissue mass. Surrounding involvement, including psoas muscle, IVC, gastrointestinal tract, and bronchi, was infrequent but may develop as critical INAA complications.

Paclitaxel-Coated Balloon Angioplasty for Early Restenosis of Central Veins in Hemodialysis Patients: A Single Center Initial Experience.

Objective: To report the results of angioplasty with paclitaxel-coated balloons for the treatment of early restenosis of central veins in hemodialysis patients. Materials and Methods: Sixteen patients (9 men and 7 women; mean age 65.8 ± 14.4 years; range, 40-82 years) with 16 episodes of early restenoses of central veins within 3 months (median patency duration 2.5 months) were enrolled from January 2014 to June 2015. Ten native central veins and 6 intra-stent central veins were treated with double paclitaxel-coated balloons (diameter 6-7 mm) plus a high pressure balloon (diameter 12-14 mm). The study outcomes included procedural success (< 30% residual stenosis) and primary patency of the treated lesion (< 50% angiographic stenosis without re-intervention). Results: Procedural success was achieved in all 16 cases of central vein stenoses. The mean diameter of the central vein was 3.7 ± 2.4 mm before the procedure vs. 11.4 ± 1.8 mm after the initial procedure. There were no procedure-related complications. The mean diameters of the central veins at 6 months and 12 months were 7.8 ± 1.3 mm and 6.9 ± 2.7 mm, respectively. The primary patency rates at 6 months and 12 months were 93.8% and 31.2%, respectively. One patient had significant restenosis of the central vein at 3 months. The median primary patency period was 9 months for paclitaxel-coated balloons and 2.5 months for the last previous procedure with conventional balloons (p < 0.001). Conclusion: In our limited study, paclitaxel-coated balloons seem to improve the patency rate in cases of early restenosis of central veins. However, a further randomized control trial is necessary.

Transarterial Embolization of a Renal Artery Aneurysm Concomitant With Renal Arteriovenous Fistula.

Congenital renal artery aneurysm is uncommon. Moreover, renal artery aneurysm concomitant with a congenital renal arteriovenous fistula is extremely rare. Transarterial embolization is the first-line treatment for these conditions. We report a case of a patient with congenital renal artery aneurysm concomitant with a congenital renal arteriovenous fistula of the upper polar left renal artery which was successfully treated by transarterial embolization with coil, glue, and Amplatzer vascular plug.

Pharmacomechanical Thrombolysis versus Surgical Thrombectomy for the Treatment of Thrombosed Haemodialysis Grafts.

INTRODUCTION: The key to treatment of a thrombosed dialysis graft is restoration and maintenance of function as long as possible. The objective of this study was to compare the outcomes of pharmacomechanical thrombolysis and surgical thrombectomy in the treatment of thrombosed haemodialysis grafts. MATERIALS AND METHODS: During a 3-year period, 108 patients with 114 thrombosed dialysis grafts were referred to our institute for treatment. Fifty thrombosed dialysis grafts underwent pulse-spray catheter thrombolysis using recombinant tissue plasminogen activator (rt-PA) with angioplasty, and 64 thrombosed dialysis grafts underwent surgical thrombectomy. The procedural success rates, complications and average patency times and patency rates were compared between the 2 procedures. P values less than 0.05 were considered to be statistically significant. RESULTS: There were no statistically significant differences between the pharmacomechanical thrombolysis group and the thrombectomy group in the procedural success rates (94% and 93.8%, P = 0.15) or average patency times (6.24 months and 6.30 months, P = 0.17). The primary and secondary patency rates at 12 months were 28.0% ± 8.4% and 54.3% ± 7.8% for the thrombolysis with angioplasty group, and 30.0% ± 6.3% and 57.0% ± 4.8% for the thrombectomy group, respectively (P = 0.65 and P = 0.49, respectively). There were no procedural-related major complications. CONCLUSION: Our study found no differences in outcomes between patients treated with pharmacomechanical thrombolysis and surgical thrombectomy for thrombosed haemodialysis grafts. Pharmacomechanical thrombolysis can be considered as an alternative treatment for dialysis graft thrombosis.

Endovascular therapy for infected aortic aneurysms.

OBJECTIVE: To determine the outcome of endovascular therapy for an infected aortic aneurysm in patients with or without aorto-aerodigestive/aortocaval fistulas. METHODS: From September 2005 to May 2010, 21 patients, 17 abdominal and four thoracic infected aortic aneurysms were treated with an endovascular stent graft at Songklanagarind Hospital, Thailand. Five patients presented with fistula complications, 1 aortoesophageal, 1 aortobronchial, 1 aortocaval, and 2 aortoenteric fistulas. Lifelong antibiotics were planned for all patients. In-hospital mortality and follow-up outcomes were examined. RESULTS: The average age was 66 years (range, 42-84) and 18 patients were male. All five cases in the fistulous group presented with symptoms related to the organs involved, four massive bleedings and one congestive heart failure. Symptoms of patients in the nonfistulous group were abdominal, back, or chest pain in 94%, fever in 81%, and diarrhea in 19%. Blood culture was positive in 10 patients (48%): eight Salmonella spp and two Burkholderia pseudomallei. The overall in-hospital mortality was 19% (4/21): 60% (3/5) in the fistula group and only 6% (1/16) in the nonfistula group. One conversion to open repair was performed in the fistula group 2 weeks after the endovascular procedure. During the follow-up period, one of the two survivors in the fistula group died at 18 months from unrelated causes, while there were no deaths in the 15 patients of the nonfistula group with an average patient follow-up of 22 months (range, 1-54). Periaortic inflammation and aneurysms in the nonfistula group completely disappeared in 10 of the 15 patients (67%). The aneurysm significantly shrunk in four patients (27%), and was stable at 1 month in one patient. There were no late conversions. CONCLUSION: Endovascular therapy, as a definite treatment for infected aortic aneurysms, provided excellent short- and medium-term results in patients without fistula complications. However, a poorer outcome was evident in patients with fistula complications.

Suprarenal endograft fixation avoids adverse outcomes associated with aortic neck angulation.

The advent of endovascular therapy has had a profound impact on repair of abdominal aortic aneurysms (AAA). Prudent patient selection, particularly in regard to unfavorable anatomy, is emerging as perhaps the most important determinant of endovascular abdominal aortic aneurysm repair (EVAR) outcome. The aim of this study was to examine the association of one such anatomic factor, proximal aortic neck angulation, with the incidence of adverse events following EVAR. Prospectively collected data on 289 EVAR repairs with the Talent endograft (Medtronic, Inc., Minneapolis, MN) from March 1998 to June 2000 were analyzed. Stent graft-specific adverse events studied were migration, endoleak, kinking, thrombosis, and AAA expansion. Computed tomography (CT) scanning with three-dimensional post-processing and/or aortography was used to measure aortic neck angle. Patients were categorized into one of four groups according to their neck angle: I (0-10 degrees); II (11-39 degrees); III (40-59 degrees); or IV (60-85 degrees). Outcomes were evaluated by chi-squared analysis and ANOVA. There was a direct correlation between AAA diameter and neck angle (p = 0.002). There was no difference in endoleak rate (p = 0.877), stent migration (p = 0.850), or AAA expansion rate (p = 0.599) between groups. Device kinking >45 degrees was associated with neck angulation > or = 60 degrees (p = 0.013), but not with other adverse outcomes. The average neck angle was 30 degrees in patients with endoleaks and 31 degrees in patients without endoleaks. Increasing aortic neck angulation was not associated with the selected adverse outcomes within 1 year following EVAR with the Talent stent graft using suprarenal fixation with the exception of graft kinking. This may be related to the graft design that permits suprarenal aortic fixatiou of the proximal stent graft, Whether severe degrees of angulation of 60 degrees or greater can be safely treated with suprarenal fixation requires further study.

Midterm pivotal trial results of the Talent Low Profile System for repair of abdominal aortic aneurysm: analysis of complicated versus uncomplicated aortic necks.

OBJECTIVE: This study was undertaken to determine whether a complicated aortic neck is associated with unfavorable outcome after abdominal aortic aneurysm (AAA) endografting. METHODS: In a prospective pivotal clinical trial, 237 consecutive patients underwent implantation of the bifurcated Talent Low Profile System. Patients were divided into 2 groups, those with complicated aortic necks (short, <15 mm; very short, < or =10 mm; dilated, >28 mm; angulated, >45 degrees; calcified; and thrombus-lined) versus those with uncomplicated neck anatomy. Major outcome parameters included procedure time, operative blood loss, transfusion requirements, volume of contrast medium used during the implant procedure, endoleaks, migration, limb patency, AAA regression, conversion to open repair, morbidity, and mortality. Mean follow-up was 620.5 days. RESULTS: Overall, 32% of aortic necks were short, 19% were very short, 20% were dilated, 18% were calcified, 8.5% were thrombus-lined, and 19.9% were angulated. Thirty percent and 70% of patients, respectively, were stratified to the uncomplicated and complicated groups ( P < .01. Procedure time, operative blood loss, transfusions, volume of contrast medium used in the implant procedure, migration, endograft patency, AAA sac regression, conversion to open repair, and mortality were not significantly different in necks with complicated versus uncomplicated anatomy. At 21 months, sacs were regressing or stable in 98% (complicated) versus 96% (uncomplicated). Primary graft limb patency was 100% in both groups. The endoleak rate was 4.3% (complicated) versus 17% (uncomplicated) at 18 months, but this difference was not statistically significant. Adverse renal events, however, occurred in 27.5% (complicated) versus 13.6% (uncomplicated; P = .04). CONCLUSIONS: Complicated aortic neck is not associated with unfavorable outcome at midterm follow-up after AAA endografting. However, statistically more adverse renal events occur in patients with complicated neck anatomy.

Unilateral lower extremity paralysis after coil embolization of an internal iliac artery aneurysm.

Neurologic complications after treatment of internal iliac artery (IIA) aneurysms are rare, especially if confined to one IIA. We report a patient in whom profound right lower extremity paresis developed after unilateral right IIA coil embolization for treatment of a 4-cm IIA aneurysm, despite the presence of a patent contralateral IIA. This case illustrates the important, yet unpredictable, nature of pelvic blood flow to the distal spinal cord and lumbosacral plexus and the unpredictable consequence of IIA occlusion.

Post-endograft abdominal aortic aneurysm shrinkage varies among hospitals: observations from multicenter trials.

PURPOSE: To evaluate differences in abdominal aortic aneurysm (AAA) shrinkage among hospitals following protocol-driven patient selection and using endografts from a single manufacturer. METHODS: Standardized inclusion criteria for the Talent endograft multicenter trials included AAA diameter >/=40 mm and proximal neck limits of length >/=5 mm, diameter 14 to 32 mm, and angle /=5-mm decrease in the AAA largest minor axis diameter. Trial sites with >10 complete study cases were selected for stepwise logistic regression analysis. In the 13 trial sites meeting this criterion, 323 patients (mean age 74; 93% men) were treated for aneurysms with a mean pretreatment diameter of 53 mm. RESULTS: At 12 months, significant AAA shrinkage occurred in 192 (59%) cases. The AAA shrinkage rate was 71% to 82% at 3 sites, 60% to 64% at 4 sites, 45% to 50% at 4 sites, and 35% and 27% at the 2 remaining sites. In the multivariate analysis, the hospital site showed a strong, independent association with aneurysm shrinkage (p<0.04). Neck and pretreatment AAA diameters were also found to be important factors (p<0.04). Age, gender, AAA classification, neck length, and angle were not significant correlates. Sixty-four (20%) endoleaks (29 type I, 34 type II, and 1 type III) were observed. The incidence of proximal endoleak was significantly different among sites (p<0.001) and highest in the 3 sites with the lowest AAA shrinkage rate. CONCLUSIONS: AAA shrinkage rates vary significantly among hospitals using the same endograft and protocol-defined patient selection criteria. Site-specific factors appear to be an important variable leading to successful endograft repair, as defined by post-endograft aneurysm shrinkage.

Computed tomography scanning for endograft planning: evolving toward three-dimensional, single source imaging.

One of the most fundamental differences between open surgical repair of aortic aneurysms and treatment by endograft exclusion is the dependency on imaging for all critically important aspects of the endovascular approach. Patient selection and preprocedure planning for device selection and sizing depend on imaging. Computed tomography (CT) scanning for endograft planning is capable of providing accurate and complete measurement data. There are problems with diameter, length, and angulation measurement when using conventional two-dimensional (2D) axial CT images that can be partly overcome by expert interpretation. However, when computerized 3D programs that include easy-to-use measurement tools process CT data, the problems of 2D CT scan data are relieved. In addition, virtual simulation of various endograft choices can be modeled within computerized renderings of patient-specific anatomy that allow testing of alternatives and provide an intuitive understanding during the planning phase.

Aortic diameter is an insensitive measurement of early aneurysm expansion after endografting.

PURPOSE: To determine the sensitivity of various methods of diameter measurement to detect abdominal aortic aneurysm (AAA) size change following endovascular grafting. METHODS: Sixty-eight patients (59 men; mean age 68 years, range 47-84) with 3-dimensional reconstruction of 196 computed tomography (CT) studies (68 preoperative, 128 follow-up) were studied. Implanted devices included 50 bifurcated and 18 straight stent-grafts. All diameter measurements were obtained from reformatted CT slices perpendicular to the center of blood flow. Three diameter measurements were made for each study: (1) transverse (TR), (2) anteroposterior (AP), and (3) maximum diameter in any orientation (Dmax). Volume measurements were calculated from the lowest main renal artery to the aortic bifurcation. Changes in diameter and volume were determined by subtracting follow-up measurements from preop measurements. Diameter and volume changes >5 mm and 10%, respectively, were considered significant. RESULTS: AAA volume significantly increased in 20 (15%) studies, decreased in 84 (66%), and remained unchanged in 24 (19%). Agreement between methods of diameter measurement (TR, AP, Dmax) and volume change were 35%, 15%, and 25% for volume increase >10%, respectively, and 70%, 88%, and 74%, respectively, for volume decrease >10%. The orientation of maximum diameter varied in individual serial exams in 19 (28%) patients. Three of 12 patients with a study showing volume increase failed to demonstrate endoleak. CONCLUSIONS: Diameter measurements were not sensitive in detecting enlarging AAA after endografting. Volume measurement determined by 3D reconstruction is the preferred method for early diagnosis of patients with enlarging AAA that may indicate increased risk of rupture after aortic endografting.

Distal internal iliac artery embolization: a procedure to avoid.

OBJECTIVES: Internal iliac artery (IIA) coil embolization as an adjunct to endovascular stent grafting (ESG) is common practice for treating abdominal aortic aneurysm (AAA) in patients with a substantially enlarged common iliac artery requiring extension of the stent-graft limb into the external iliac artery. The literature describing pelvic ischemia in association with IIA coil embolization contains conflicting reports of symptom severity. We studied IIA occlusion outcome as a function of coil placement in the IIA. METHODS: From August 1997 to March 2002, 20 patients with AAA underwent ESG with unilateral IIA coil embolization. Coils were placed proximal to the first branch of the IIA in 8 patients and distal to the first branch in 12 patients. Symptoms of pelvic ischemia and mid-term outcome were studied. RESULTS: Patients included 18 men and 2 women with mean age of 70(1/2) years (range, 53-86 years). Mean diameter of AAA was 54.4 mm (range, 38-80 mm), and of common iliac artery was 24.2 mm (range, 15-48 mm). Ten patients (50%) had new onset of symptoms of pelvic ischemia after endograft procedures: 1 of 8 patients (13%) with proximal IIA embolization had buttock claudication, and 9 of 12 patients (75%) with distal IIA embolization had pelvic ischemic symptoms, including buttock claudication in 8 and impotence in 1 (P =.02, Fisher exact test). No colonic ischemia occurred in this series. At 12-month follow-up, 4 patients with distal IIA embolization were symptom-free. At further follow-up to 24 months, 4 patients remained significantly limited with symptoms of claudication. CONCLUSIONS: A significantly higher incidence of symptoms of pelvic ischemia occurred with more distal placement of coils for IIA embolization. Failure to control for extent of coil placement may account for the apparently conflicting results in published studies. IIA coil embolization should be performed as proximal as possible to prevent interference with pelvic collateral circulation.

Internal iliac artery occlusion using a stent-graft tunnel during endovascular aneurysm repair: a new alternative to coil embolization.

PURPOSE: To report a new endovascular technique for internal iliac artery (IIA) occlusion during stent-graft treatment in patients with aortoiliac aneurysm. TECHNIQUE: Stent-grafts measuring 20 to 28 mm in diameter and 37.5 mm long were deployed at the iliac bifurcation to occlude the IIA at its origin. Subsequent deployment of an aortic bifurcation endograft with ipsilateral extension into the external iliac artery was through this iliac stent-graft tunnel. This approach has been used in 5 patients with abdominal aortic aneurysm and common iliac artery aneurysm (n=4) or isolated iliac artery aneurysm. Proximal IIA occlusion was achieved in all cases with no distal type I endoleak. IIA patency on the side opposite to the tunnel procedure was preserved in each case. No patient described new onset of pelvic ischemic symptoms. Over a mean 10-month follow-up (range 1-12), there was no secondary procedure required for type I endoleak. Three patients had a CIA aneurysm diameter change of -1, -4, and 0 mm at 1 year. CONCLUSIONS: This new method for IIA occlusion at its origin without coil embolization may prove to be a useful adjunct to endovascular aortoiliac aneurysm repair. The technique is simple, rapid, and may minimize the risk of pelvic ischemia.

Bell-bottom aortoiliac endografts: an alternative that preserves pelvic blood flow.

OBJECTIVE: Dilated common iliac arteries that complicate aortic aneurysm stent grafting usually have been managed with endograft extension across the iliac artery bifurcation with internal iliac artery (IIA) occlusion. We studied 25 patients with significant common iliac artery (CIA) dilation treated with two methods: endograft extension across the iliac bifurcation or a new approach with a flared cuff within the CIA that preserves the IIA. METHODS: Of 86 patients with abdominal aortic aneurysm (AAA) who underwent bifurcated endovascular stent grafting (ESG), 25 (29.1%) had at least one dilated CIA. Two treatment groups had different methods of management of iliac artery dilation. Group 1 underwent ESG with straight extension across the iliac bifurcation and IIA coil embolization before the ESG procedure (n = 2) or simultaneously with ESG (n = 8). Group 2 underwent ESG with flared distal cuff (AneuRx, Medtronic AVE, Santa Rosa, Calif) contained within the CIA, the so-called "bell-bottom" procedure, thus preserving the IIA (n = 15). Iliac artery dimensions, operating room time, fluoroscopy time, and postoperative complications were prospectively gathered. RESULTS: Two women and 23 men had mean diameters of AAA of 56.6 mm (range, 38 to 98 mm) and of CIA of 21.4 mm (range, 15 to 48 mm). The diameters of CIA treated with device extension into external iliac artery after IIA coil embolization in group 1 and with the bell-bottom procedure in group 2 were not different (mean CIA diameter, 19.9 mm; range, 15 to 26 mm; and mean, 19.1 mm; range, 15 to 24 mm; respectively). However, significantly lower operating room and catheter procedure times were found in group 2 compared with group 1 (137 versus 192 minutes; 58 versus 106 minutes; P =.02 and.02, respectively). No periprocedural type I endoleaks were found in either group. Nine patients in group 2 also had a second contralateral CIA aneurysm, and five patients (mean CIA diameter, 33.0 mm; range, 22 to 48 mm) underwent treatment with extension across the iliac artery bifurcation and IIA occlusion. Use of the bell-bottom procedure on the other side allowed preservation of one IIA. Four cases (mean diameter, 19.3 mm) also underwent contralateral bell-bottom procedure. Two of these group 2 patients had complications, with severe buttock claudication in one and distal embolism necessitating limb salvage bypass after preoperative coil embolization of the IIA in another. CONCLUSION: Significant CIA ectasia or small aneurysm is often associated with AAA. In such cases, the bell-bottom procedure that preserves IIA circulation is a new alternative to the common practice of placement of endograft extensions across the iliac artery bifurcation in patients with at least one CIA diameter of less than 26 mm. Additional benefits include reduced total procedure time. Early technical success appears to justify continued use. However, long-term evaluation is necessary to determine durability because the risk of rupture as the result of potential expansion of the excluded iliac artery or late failure is unknown.

CT artifacts of the proximal aortic neck: an important problem in endograft planning.

PURPOSE: To describe the imaging error introduced by noncircular abdominal aortic aneurysm (AAA) necks in axial and reformatted computed tomographic (CT) images and discuss the potential implications for aortic endografting. METHODS: The records of 120 endograft patients with preoperative CT axial scans and subsequent 3-dimensional (3D) computerized reconstructions were reviewed. Maximum and minimum infrarenal aortic neck diameters were measured from axial CT scans and 3D reformatted slices at the same point on the vessel. Diameter measurements were made at the largest point within the 10-mm segment of vessel below the lowest renal artery. Excluded were aneurysms with proximal neck minimum diameters >30 mm, neck lengths < 15 mm, or angulation > 75 degrees measured on the axial CT slice. RESULTS: Measuring from reformatted CT slices, 86 (71.6%) cases had < or = 2-mm differences between maximal and minimal neck diameters, comprising the "round neck" group A. In 34 (28.4%) cases, the neck was not round: 26 (21.7%) had diameter differences between 2 and 4 mm (group B) and 8 (6.7%) had a > 4-mm difference (group C; range 4.1-8.1 mm). Although AAA diameter, neck length, and neck angle progressively increased as the difference between neck maximum and minimum diameters grew, i.e., greater eccentricity, these trends did not reach statistical significance. Mean infrarenal neck maximum diameter was significantly larger in group C (30.2 +/- 3.4 mm) compared to groups A (23.0 +/- 2.9 mm, p = 0.0002) and B (23.8 +/- 3.6 mm, p = 0.0003). Hence, 28.4% of AAAs had a noncircular aortic neck of varying degree, and 6.7% had an eccentricity factor that may have clinical significance. CONCLUSIONS: This study confirms the importance of selecting an endoprosthesis sized 15% to 20% larger than the infrarenal aortic neck diameter. Three-dimensional reconstruction using reformatted CT slices perpendicular to the flow lumen is an important tool that offers enhanced accuracy of infrarenal aortic neck evaluation.