Postoperative serum mir-28-5p level has predictive value for the prognosis after endovascular abdominal aortic aneurysm repair.

BACKGROUND: We explored the clinical significance of miR-28-5p pre- and post-endovascular abdominal aortic aneurysm repair (EVAR) in abdominal aortic aneurysm (AAA) patients. METHODS: Subjects included AAA patients receiving EVAR and non-AAA people without statistical differences from AAA patient in comorbidities/Framingham risk score. Fasting elbow venous blood (4 mL) was collected in the morning of the day of EVAR surgery and in the morning of 3 months post-EVAR. Pre-/post-EVAR serum miR-28-5p expression, AAA maximum diameter alterations, CD3+/CD4+/CD8+/TC/TG pre-/post-EVAR, and the correlations between miR-28-5p and AAA maximum diameter were investigated. Prediction of miR-28-5p on post-EVAR mortality, prognosis, and independent factors of post-EVAR death were analyzed using receiver operating characteristic curve (ROC)/Kaplan-Meier curve/univariable and multivariable Cox regression. According to the cut-off value of ROC curve for postoperative miR-28-5p was the cut-off value, and the patients were classified into the miR-28-5p high- and low-expression groups. The survival or death of both groups were compared after 48-month follow-up. RESULTS: Serum miR-28-5p levels in AAA patients dropped post-EVAR. AAA patients showed notable differences in CD3+/CD4+/CD8+/TC/TG levels pre-/post-EVAR. The miR-28-5p low-expression group exhibited higher CD3+/CD4+ and lower CD8+/TC/TG levels. We observed a positive correlation between post-EVAR miR-28-5p and AAA maximum diameter and between the pre-/post-EVAR miR-28-5p fold change and the AAA maximum diameter change. Postoperative miR-28-5p demonstrated good predictive value for postoperative death. Hypertension, Framingham risk score, TC, TG, and miR-28-5p were independent influencing factors of post-EVAR death. CONCLUSION: EVAR decreased serum miR-28-5p expression in AAA patients. Post-operative miR-28-5p level and pre-/post-operative fold change level are positively-correlated with AAA diameter.

Characteristics and 1-year outcomes of patients with rupture of small abdominal aortic aneurysms.

OBJECTIVES: Ruptured abdominal aortic aneurysms (rAAA) are associated typically with a large sac diameter; however, some patients experience rupture before reaching operative thresholds for elective repair. We aim to investigate the characteristics and outcomes of patients who experience small rAAA. METHODS: The Vascular Quality Initiative database for open AAA repair and endovascular aneurysm repair from 2003 to 2020 were reviewed for all rAAA cases. Based on the 2018 Society for Vascular Surgery guidelines on operative size thresholds for elective repair, patients with infrarenal aneurysms of less than 5.0 cm in women or less than 5.5 cm in men were categorized as a small rAAA. Patients who met operative thresholds or had a concomitant iliac diameter 3.5 cm or greater were categorized as a large rAAA. Patient characteristics and perioperative as well as long-term outcomes were compared via univariate regression. Inverse probability of treatment weighting using propensity scores was used to examine the relationship between rAAA size and adverse outcomes. RESULTS: There were 3962 cases that met inclusion criteria, with 12.2% small rAAA. The mean aneurysm diameter was 42.3 mm and 78.5 mm in the small and large rAAA groups, respectively. Patients in the small rAAA group were significantly more likely to be younger, African American, have a lower body mass index, and had significantly higher rates of hypertension. Small rAAA were more likely to be repaired via endovascular aneurysm repair (P = .001). Hypotension was significantly less likely in patients with small rAAA (P<.001). Rates of perioperative myocardial infarction (P < .001), total morbidity (P < .004) and mortality (P < .001) were significantly higher for large rAAA cases. After propensity matching, there was no significant difference in mortality between the two groups, but smaller rAAA was associated with lower rates of myocardial infarction (odds ratio, 0.50; 95% confidence interval, 0.31-0.82). On long-term follow-up, no difference in mortality was noted between the two groups. CONCLUSIONS: Patients presenting with small rAAA represent 12.2% of all rAAA and are more likely to be African American. Small rAAA is associated with similar risk of perioperative and long-term mortality compared with rupture at larger size after risk adjustment.

Iliac Artery Aneurysms Expand in Quadratically Proportion to the Diameter.

BACKGROUND: Iliac artery aneurysms (IAAs) are life-threatening once ruptured. Although some studies have revealed the pathology of IAAs, clinical information on IAAs is still limited. Moreover, previous studies were conducted in Western countries; thus, we aimed to identify the natural history of iliac artery aneurysms in a Japanese cohort. The purpose of this study was to investigate the IAA expansion rate in a Japanese cohort to consider the management of small IAAs and to identify indications for surgical intervention. METHODS: Patients with iliac artery aneurysms were retrospectively reviewed. The primary outcome was the expansion rate of IAAs. We also investigated the correlation between expansion rate and patients' characteristics. Natural histories, including surgical interventions and rupture, were also assessed. RESULTS: The mean expansion rate in our study was 1.59 ± 1.16 mm/year. There was a positive correlation between expansion rate and aneurysm diameter, which was estimated by y = 0.0052 × (X - 23.270)2 + 0.0632 × X - 0.0517, where y is the expansion rate, and X is aneurysm diameter. The freedom from surgical intervention rate of IAAs was 85.5% at 1 year, 54.0% at 3 years, and 41.5% at 5 years. No factors, except initial aneurysm diameter, were revealed as independent predictors of surgical intervention. We experienced one ruptured IAA, which showed unexpected rapid growth from 30.1 mm to 56.3 mm over 15 months during conservative management. This case demonstrated that IAAs ≥30 mm should be carefully followed up and considered for surgical intervention. CONCLUSIONS: We conclude that larger aneurysms have greater expansion rates. Because IAAs ≥30 mm carry a risk of rapid expansion resulting in rupture, careful follow-up, and surgical intervention should be performed if iliac artery aneurysms are ≥30 mm in diameter.

Associations of Genes for Killer Cell Immunoglobulin-like Receptors and Their Human Leukocyte Antigen-A/B/C Ligands with Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) is an immune-mediated disease with a genetic component. The multifactorial pathophysiology is not clear and there is still no pharmacotherapy to slow the growth of aneurysms. The signal integration of cell-surface KIRs (killer cell immunoglobulin-like receptors) with HLA (ligands, human leukocyte class I antigen molecules) modulates the activity of natural killer immune cells. The genetic diversity of the KIR/HLA system is associated with the risk of immune disorders. This study was a multivariate analysis of the association between genetic variants of KIRs, HLA ligands, clinical data and AAA formation. Genotyping was performed by single polymerase chain reaction with sequence-specific primers using commercial assays. Patients with HLA-A-Bw4 have a larger aneurysm by an average of 4 mm (p = 0.008). We observed a relationship between aneurysm diameter and BMI in patients with AAA and co-existing CAD; its shape was determined by the presence of HLA-A-Bw4. There was also a nearly 10% difference in KIR3DL1 allele frequency between the study and control groups. High expression of the cell surface receptor KIR3DL1 may protect, to some extent, against AAA. The presence of HLA-A-Bw4 may affect the rate of aneurysm growth and represents a potential regional pathogenetic risk of autoimmune injury to the aneurysmal aorta.

Correlation of Baseline Plasma and Inguinal Connective Tissue Metalloproteinases and Their Inhibitors With Late High-Pressure Endoleak After Endovascular Aneurysm Repair: Long-term Results.

Purpose: To investigate whether plasma and connective tissue matrix metalloproteinases (MMP) and their inhibitors (TIMP) may predict late high-pressure endoleak after endovascular aneurysm repair (EVAR). Materials and Methods: Samples of inguinal fascia and blood were collected in 72 consecutive patients (mean age 73.1 years; 68 men) undergoing primary EVAR with the Endurant stent-graft. Baseline plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 and baseline MMP-2 and MMP-9 activity estimated using gelatin zymography (GZ) were compared between patients who developed late endoleak in follow-up and those who did not. Subgroup analyses were performed between patients with (n=18) and without inguinal hernias and between patients with moderate-diameter (50-59 mm; n=45) or large-diameter (≥60 mm; n=27) abdominal aortic aneurysms (AAA) at primary EVAR. Results: The mean follow-up period was 63.1 months (range 7.5-91.5), during which time 13 (18.1%) patients developed type I (6 Ia and 5 Ib) or 2 type III endoleaks. Only GZ-analyzed proMMP-9 concentrations were higher in the endoleak group than in patients without endoleak (mean difference 8.44, 95% CI -19.653 to -1.087, p=0.03). The patients with primary inguinal hernia at presentation had significantly higher tissue TIMP-2 values (0.8±0.7 vs 0.5±0.4, p=0.018) but lower plasma total (pro- + active) MMP-9 values (11.9±7.8 vs 16.2±7.4, p=0.042) than patients without hernias at the time of EVAR. Patients with AAAs ≥60 mm had significantly higher mean tissue homogenate levels of total (pro- + active) MMP-9 (p=0.025) and total (pro- + active) MMP-2 (p=0.049) as well as higher proMMP-9 (p=0.018) and total (pro- + active) MMP-9 (p=0.021) levels based on GZ compared to patients with moderate-diameter AAAs. Regression analysis revealed a significant association between total (pro- + active) MMP-9 plasma samples and the presence of hernia (OR 0.899, 95% CI 0.817 to 0.989, p=0.029) and between GZ-analyzed proMMP-9 and late endoleak (OR 1.055, 95% CI 1.007 to 1.106, p=0.025). GZ-analyzed proMMP-9 and active MMP-9 were strong predictors of late endoleak in patients with hernia (p=0.012 and p=0.044, respectively) and in patients with AAAs ≥60 mm (p=0.018 and p=0.041 respectively). Conclusion: Inguinal fascial tissue proMMP-9 significantly predicted late endoleak. ProMMP-9 and active MMP-9 biomarkers are significantly associated with late endoleak in hernia patients and in patients with AAAs ≥60 mm. Considering the clinical association between hernia and AAA and the fact that the AAA wall connective tissue environment remains exposed to systemic circulation after EVAR, inguinal fascia extracellular matrix dysregulation and altered MMP activity may reflect similar changes in AAA biology, leading to complications such as endoleak.

CTA Assessment of Midterm Morphological Changes to Chimney Grafts Used in the Treatment of Juxtarenal Aortic Aneurysms.

Purpose: To evaluate chimney stent-graft position and morphological changes of the aneurysm sac as visualized by postoperative computed tomography angiography (CTA) over a minimum 24-month follow-up period. Materials and Methods: Twenty-one patients (mean age 75.7±8.6 years; 20 men) with juxtarenal aortic aneurysms who underwent successful chimney endovascular aneurysm repair (ch-EVAR) with the Endurant stent-graft and had 2 postoperative CTAs separated by at least 24 months were included in the study. CTA-based measurements of aortic stent-graft migration, target vessel angle, and chimney angle were compared between the serial scans. Results: During a mean follow-up of 34.9 months (range 24-69.2), the mean migration of the aortic stent-grafts was under 5 mm (2.76±2.4 mm). The average migration distance per year was 1.15 mm. The aneurysm diameter reduced a mean 3.25 mm (p=0.048). The right renal artery angle moved significantly upward 6.72° (p=0.025), while the right renal chimney stent-graft moved significantly downward 7.83° (p=0.042). The left renal artery angle also moved upward 1.87° (p=0.388) and the corresponding chimney moved downward 5.68° (p=0.133). During the study period, no type I/III endoleak or chimney occlusion was observed. Conclusion: Midterm morphometric assessment of ch-EVAR using CTA showed significant aneurysm sac shrinkage and a stable 3-year position of the abdominal devices, with the mean downward migration of the aortic stent-graft being <5 mm in the majority of cases. The chimney grafts seem to be prone to take an oblique rather than parallel configuration during follow-up. However, there was no relevant clinical consequence related to this phenomenon.

Effects of Abdominal Aortic Aneurysm Size on Mid- and Long-term Mortality After Endovascular Aneurysm Repair.

PURPOSE: To investigate the effect of abdominal aortic aneurysm (AAA) size on mid- and long-term survival after endovascular aneurysm repair (EVAR). MATERIALS AND METHODS: Retrospective data were collected from 325 consecutive patients (mean age 69.7 ± 8.5 years; 323 men) who underwent EVAR for intact AAA at a single institution between January 2003 and December 2013. The primary endpoint was death at 3, 5, and 10 years after EVAR. Optimal cutoff points for AAA size and age were determined using receiver operating characteristics (ROC) curves. Time to event analyses (Kaplan-Meier curves and Cox proportional hazard models) were employed to determine any differences in all-cause mortality outcomes between AAA size groups. Cox models were adjusted for age and other comorbidities (hypertension, hyperlipidemia, coronary artery disease, smoking status, symptomatic status, and creatinine); the outcomes are reported as the hazard ratio (HR) with 95% confidence interval (CI). RESULTS: The cohort was dichotomized according to the ROC analysis, which defined an optimal cutoff point of 5.6 cm for AAA size and >70 years for age. The mean follow-up period post EVAR was 45.5±29.2 months. In total, 134 (41.2%) patients died during the 10-year follow-up. Thirty-day mortality was 1.1% (2/184) in the patients with AAA <5.6 cm and 2.1% (3/141) in patients with AAA ≥5.6 cm (p=0.45). All-cause mortality was not significantly affected by comorbidities. However, AAA size ≥5.6 cm was associated with increased 3-year mortality risk (HR 1.59, 95% CI 1.001 to 2.52, p<0.049) but not 5-year (HR 1.44, 95% CI 0.98 to 2.10, p=0.062) or 10-year mortality (HR 1.28, 95% CI 0.91 to 1.80, p=0.149). After adjusting for comorbidities, AAA size ≥5.6 cm was no longer significantly associated with morality at any time point. Using a larger size cutoff (AAA size ≥6.0 cm) resulted in improved statistical significance in the unadjusted model. In the adjusted Cox model, AAA size ≥6.0 cm was significantly associated with increased risk of mortality at 3 years (HR 1.67, 95% CI 1.01 to 2.77, p<0.047), but not at longer time points. CONCLUSION: Our study demonstrates that midterm survival after EVAR is significantly and independently associated with AAA size even after correcting for comorbidities. However, in the long term, preoperative AAA size is not an independent predictor of mortality.

Aortic Lumen Area Is Increased in Ruptured Abdominal Aortic Aneurysms and Correlates to Biomechanical Rupture Risk.

PURPOSE: To investigate how 2-dimensional geometric parameters differ between ruptured and asymptomatic abdominal aortic aneurysms (AAAs) and provide a biomechanical explanation for the findings. METHODS: The computed tomography angiography (CTA) scans of 30 patients (mean age 77±10 years; 23 men) with ruptured AAAs and 60 patients (mean age 76±8 years; 46 men) with asymptomatic AAAs were used to measure maximum sac diameter along the center lumen line, the cross-sectional lumen area, the total vessel area, the intraluminal thrombus (ILT) area, and corresponding volumes. The CTA data were segmented to create 3-dimensional patient-specific models for finite element analysis to compute peak wall stress (PWS) and the peak wall rupture index (PWRI). To reduce confounding from the maximum diameter, 2 diameter-matched groups were selected from the initial patient cohorts: 28 ruptured AAAs and another with 15 intact AAAs (diameters 74±12 vs 73±11, p=0.67). A multivariate model including the maximum diameter, the lumen area, and the ILT area of the 60 intact aneurysms was employed to predict biomechanical rupture risk parameters. RESULTS: In the diameter-matched subgroup comparison, ruptured AAAs had a significantly larger cross-sectional lumen area (1954±1254 vs 1120±623 mm2, p=0.023) and lower ILT area ratio (55±24 vs 68±24, p=0.037). The ILT area (2836±1462 vs 2385±1364 mm2, p=0.282) and the total vessel area (3956±1170 vs 4338±1388 mm2, p=0.384) did not differ statistically between ruptured and intact aneurysms. The PWRI was increased in ruptured AAAs (0.80 vs 0.48, p<0.001), but the PWS was similar (249 vs 284 kPa, p=0.194). In multivariate regression analysis, lumen area was significantly positively associated with both PWS (p<0.001) and PWRI (p<0.01). The ILT area was also significantly positively associated with PWS (p<0.001) but only weakly with PWRI (p<0.01). The lumen area conferred a higher risk increase in both PWS and PWRI when compared with the ILT area. CONCLUSION: The lumen area is increased in ruptured AAAs compared to diameter-matched asymptomatic AAAs. Furthermore, this finding may in part be explained by a relationship with biomechanical rupture risk parameters, in which lumen area, irrespective of maximum diameter, increases PWS and PWRI. These observations thus suggest a possible method to improve prediction of rupture risk in AAAs by measuring the lumen area without the use of computational modeling.

In Vitro Quantification of Gutter Formation and Chimney Graft Compression in Chimney EVAR Stent-Graft Configurations Using Electrocardiography-Gated Computed Tomography.

PURPOSE: To assess the dynamic behavior of chimney grafts during the cardiac cycle. METHODS: Three chimney endovascular aneurysm repair (EVAR) stent-graft configurations (Endurant and Advanta V12, Endurant and Viabahn, and Endurant and BeGraft) were placed in silicone aneurysm models and subjected to physiologic flow. Electrocardiography (ECG)-gated contrast-enhanced computed tomography was used to visualize geometric changes during the cardiac cycle. Endograft and chimney graft surface, gutter volume, chimney graft angulation over the center lumen line, and the D-ratio (the ratio between the lengths of the major and minor axes) were independently assessed by 2 observers at 10 time points in the cardiac cycle. RESULTS: Both gutter volumes and chimney graft geometry changed significantly during the cardiac cycle in all 3 configurations (p<0.001). Gutters and endoleaks were observed in all configurations. The largest gutter volume (232.8 mm3) and change in volume (20.7 mm3) between systole and diastole were observed in the Endurant-Advanta configuration. These values were 2.7- and 3.0-fold higher, respectively, compared to the Endurant-Viabahn configuration and 1.7- and 1.6-fold higher as observed in the Endurant-BeGraft configuration. The Endurant-Viabahn configuration had the highest D-ratio (right, 1.26-1.35; left, 1.33-1.48), while the Endurant-BeGraft configuration had the lowest (right, 1.11-1.17; left, 1.08-1.15). Assessment of the interobserver variability showed a high correlation (intraclass correlation >0.935) between measurements. CONCLUSION: Gutter volumes and stent compression are dynamic phenomena that reshape during the cardiac cycle. Compelling differences were observed during the cardiac cycle in all configurations, with the self-expanding (Endurant-Viabahn) chimney EVAR configurations having smaller gutters and less variation in gutter volume during the cardiac cycle yet more stent compression without affecting the chimney graft surface.

Follow-up on Small Abdominal Aortic Aneurysms Using Three Dimensional Ultrasound: Volume Versus Diameter.

OBJECTIVES: Rupture risk in abdominal aortic aneurysms (AAAs) is assessed using AAA diameter; yet 10% of ruptures occur in a small aneurysm. This underlines the inadequacy of diameter as a standalone parameter. In this prospective follow-up study, ultrasound determined aneurysm diameter was compared with aneurysm volume determined by three dimensional ultrasound (3D-US) in a group of 179 AAAs. DESIGN: This was a prospective cohort study with repeated diameter and volume measurements by 3D-US. MATERIAL AND METHODS: In total, 179 patients with small infrarenal AAAs (diameter 30-55 mm) were enrolled consecutively. At enrolment and at 12 month follow-up, maximum diameter, using dual plane technique, and three dimensional volume were measured. Based on a previous accuracy study, significant change in diameter and volume were defined as an increase exceeding the known range of variability (ROV) of each US technique; ±3.7 mm and ±8.8 mL, respectively. Post-hoc Kaplan-Meier analysis was performed to estimate time to conversion to treatment after the conclusion of the follow-up period between two groups. RESULTS: In total, 125 patients (70%) had an unchanged diameter during follow-up. In this group, 50 patients (40%) had an increasing aortic volume. Forty-five (83%) of the 54 patients with an increasing aortic diameter showed a corresponding volume increase. During a median follow-up of 367 days (364-380 days), a mean increase in diameter of 2.7 mm (±2.6 mm) and a mean increase in volume of 11.6 mL (±9.9 mL) were recorded. In post-hoc analysis, it was found that more AAAs with a stable diameter and a growing volume than AAAs with a stable diameter and volume were undergoing aortic repair during follow-up, based on the maximum diameter. CONCLUSION: In this cohort of small AAAs, 40% of patients with a stable diameter had an increasing volume at 12 month follow-up. From this perspective, 3D-US could have a future supplemental role in AAA surveillance programmes.

Aortic Curvature Is a Predictor of Late Type Ia Endoleak and Migration After Endovascular Aneurysm Repair.

PURPOSE: To evaluate the association between aortic curvature and other preoperative anatomical characteristics and late (>1 year) type Ia endoleak and endograft migration in endovascular aneurysm repair (EVAR) patients. METHODS: Eight high-volume EVAR centers contributed 116 EVAR patients (mean age 81±7 years; 103 men) to the study: 36 patients (mean age 82±7 years; 31 men) with endograft migration and/or type Ia endoleak diagnosed >1 year after the initial EVAR and 80 controls without early or late complications. Aortic curvature was calculated from the preoperative computed tomography scan as the maximum and average curvature over 5 predefined aortic segments: the entire infrarenal aortic neck, aneurysm sac, and the suprarenal, juxtarenal, and infrarenal aorta. Other morphological characteristics included neck length, neck diameter, mural neck calcification and thrombus, suprarenal and infrarenal angulation, and largest aneurysm sac diameter. Independent risk factors were identified using backward stepwise logistic regression. Relevant cutoff values for each of the variables in the final regression model were determined with the receiver operator characteristic curve. RESULTS: Logistic regression identified maximum curvature over the length of the aneurysm sac (>47 m-1; p=0.023), largest aneurysm sac diameter (>56 mm; p=0.028), and mural neck thrombus (>11° circumference; p<0.001) as independent predictors of late migration and type Ia endoleak. CONCLUSION: Aortic curvature is a predictor for late type Ia endoleak and endograft migration after EVAR. These findings suggest that aortic curvature is a better parameter than angulation to predict post-EVAR failure and should be included as a hostile neck parameter.

A Systematic Review of Ultrasound or Magnetic Resonance Imaging Compared With Computed Tomography for Endoleak Detection and Aneurysm Diameter Measurement After Endovascular Aneurysm Repair.

PURPOSE: To analyze the literature comparing ultrasound [duplex (DUS) or contrast-enhanced (CEUS)] or magnetic resonance imaging (MRI) with computed tomography angiography (CTA) for endoleak detection and aneurysm diameter measurement after endovascular aneurysm repair (EVAR). METHODS: A systematic review identified 31 studies that included 3853 EVAR patients who had paired scans (DUS or CEUS vs CTA or MRI vs CTA) within a 1-month interval for identification of endoleaks during EVAR surveillance. The primary outcome was the number of patients with an endoleak detected by one test but undetected by another test. Results are presented for all endoleaks and for types I and III endoleaks only. Aneurysm diameter measurements between CTA and ultrasound were examined using meta-analysis. RESULTS: Endoleaks were seen in 25.6% (985/3853) of patients after EVAR. Fifteen studies compared DUS with CTA for the detection of all endoleak types. CTA had a significantly higher proportion of additional endoleaks detected (214/2346 vs 77/2346 for DUS). Of 19 studies comparing CEUS with CTA for the detection of all endoleak types, CEUS was more sensitive (138/1694) vs CTA (51/1694). MRI detected 42 additional endoleaks that were undetected by CTA during the paired scans, whereas CTA detected 2 additional endoleaks that MRI did not show. CTA had a similar proportion of additional types I and III endoleaks undetected by CEUS or MRI. Of 9 studies comparing ultrasound vs CTA for post-EVAR aneurysm diameter measurement, the aneurysm diameter measured by CTA was greater than ultrasound (mean difference -1.70 mm, 95% confidence interval -2.45 to -0.96, p<0.001). CONCLUSION: This study demonstrated that CEUS and MRI are more accurate than CTA for the detection of post-EVAR endoleaks, but they are no better than CTA for detecting types I and III endoleaks specifically. Aneurysm diameter differences between CTA and ultrasound should be considered when evaluating the change in aneurysm diameter postoperatively.

Local Diameter, Wall Stress, and Thrombus Thickness Influence the Local Growth of Abdominal Aortic Aneurysms.

PURPOSE: To investigate the influence of the local diameter, the intraluminal thrombus (ILT) thickness, and wall stress on the local growth rate of abdominal aortic aneurysms. METHODS: The infrarenal aortas of 90 asymptomatic abdominal aortic aneurysm (AAA) patients (mean age 70 years; 77 men) were retrospectively reconstructed from at least 2 computed tomography angiography scans (median follow-up of 1 year) and biomechanically analyzed with the finite element method. Each individual AAA model was automatically sliced orthogonally to the lumen centerline and represented by 100 cross sections with corresponding diameters, ILT thicknesses, and wall stresses. The data were grouped according to these parameters for comparison of differences among the variables. RESULTS: Diameter growth was continuously distributed over the entire aneurysm sac, reaching absolute and relative median peaks of 3.06 mm/y and 7.3%/y, respectively. The local growth rate was dependent on the local baseline diameter, the local ILT thickness, and for wall segments not covered by ILT, also on the local wall stress level (all p<0.001). For wall segments that were covered by a thick ILT layer, wall stress did not affect the growth rate (p=0.08). CONCLUSION: Diameter is not only a strong global predictor but also a local predictor of aneurysm growth. In addition, and independent of the diameter, the ILT thickness and wall stress (for the ILT-free wall) also influence the local growth rate. The high stress sensitivity of nondilated aortic walls suggests that wall stress peaks could initiate AAA formation. In contrast, local diameters and ILT thicknesses determine AAA growth for dilated and ILT-covered aortic walls.

Standardized 2D ultrasound versus 3D/4D ultrasound and image fusion for measurement of aortic aneurysm diameter in follow-up after EVAR.

PURPOSE: To compare standardised 2D ultrasound (US) to the novel ultrasonographic imaging techniques 3D/4D US and image fusion (combined real-time display of B mode and CT scan) for routine measurement of aortic diameter in follow-up after endovascular aortic aneurysm repair (EVAR). METHOD AND MATERIALS: 300 measurements were performed on 20 patients after EVAR by one experienced sonographer (3rd degree of the German society of ultrasound (DEGUM)) with a high-end ultrasound machine and a convex probe (1-5 MHz). An internally standardized scanning protocol of the aortic aneurysm diameter in B mode used a so called leading-edge method. In summary, five different US methods (2D, 3D free-hand, magnetic field tracked 3D - Curefab™, 4D volume sweep, image fusion), each including contrast-enhanced ultrasound (CEUS), were used for measurement of the maximum aortic aneurysm diameter. Standardized 2D sonography was the defined reference standard for statistical analysis. CEUS was used for endoleak detection. RESULTS: Technical success was 100%. In augmented transverse imaging the mean aortic anteroposterior (AP) diameter was 4.0±1.3 cm for 2D US, 4.0±1.2 cm for 3D Curefab™, and 3.9±1.3 cm for 4D US and 4.0±1.2 for image fusion. The mean differences were below 1 mm (0.2-0.9 mm). Concerning estimation of aneurysm growth, agreement was found between 2D, 3D and 4D US in 19 of the 20 patients (95%). Definitive decision could always be made by image fusion. CEUS was combined with all methods and detected two out of the 20 patients (10%) with an endoleak type II. In one case, endoleak feeding arteries remained unclear with 2D CEUS but could be clearly localized by 3D CEUS and image fusion. CONCLUSION: Standardized 2D US allows adequate routine follow-up of maximum aortic aneurysm diameter after EVAR. Image Fusion enables a definitive statement about aneurysm growth without the need for new CT imaging by combining the postoperative CT scan with real-time B mode in a dual image display. 3D/4D CEUS and image fusion can improve endoleak characterization in selected cases but are not mandatory for routine practice.

Late mortality in females after endovascular aneurysm repair.

BACKGROUND: Abdominal aortic aneurysm (AAA) rupture is an adverse arterial remodeling event with high mortality risk. Because females have increased rupture risk with smaller AAAs (<5.5 cm), many recommend elective repair before the AAA reaches 5.5 cm. Elective repair improves survival for large AAAs, but long-term benefits of endovascular aneurysm repair (EVAR) for small AAAs in females remain less understood. The objective of this study was to identify if differences in late mortality exist between females undergoing elective EVAR at our institution for small and/or slow-growing AAAs compared with those who meet standard criteria. METHODS: We retrospectively analyzed all patients that underwent EVAR for infrarenal AAA from June, 2009-June, 2013. We excluded patients that were male, treated emergently or for iliac artery aneurysm, and that received renal and/or mesenteric artery stenting. Patients did not meet anatomic criteria if preoperative AAA diameter was <5.5 cm or enlarged <0.5 cm over 6 mo. Late mortality was assessed from the social security death index. RESULTS: Thirty-six of 162 elective EVAR patients (22.2%) were female (mean follow-up, 37.2 mo). Twenty patients (55.6%) met AAA size and/or growth criteria, whereas 16 (44.4%) did not meet criteria. Despite comparable demographics, comorbidities, and complications, patients that did not meet criteria had higher late mortality (37.5% versus 5%; P = 0.03) with a trend toward increased reoperation rate (25% versus. 5%; P = 0.48). Meeting size and/or growth criteria decreased odds of late death (odds ratio, 0.09; 95% confidence intervals, 0.01-0.83). CONCLUSIONS: There is increased late mortality in females receiving elective EVAR at our institution for small and/or slow-growing AAAs. This late mortality may limit the benefits of EVAR for this population.