Assessment of Abdominal Aortic Aneurysm Risk: Asymmetry as an Additional Diagnostic Tool?

2008 ◽  
Author(s):  
Barry J. Doyle ◽  
Anthony Callanan ◽  
Michael T. Walsh ◽  
David A. Vorp ◽  
Timothy M. McGloughlin
Keyword(s):  
Risk Factors ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Surgical Intervention ◽  
Current Trend ◽  
Wall Stress ◽  
Posterior Wall ◽  
Maximum Diameter ◽  
Infrarenal Aorta ◽  
Abdominal Aortic

An abdominal aortic aneurysm (AAA) can be defined as a permanent and irreversible localised dilation of the infrarenal aorta. This localised dilation is a result of a degradation of the elastic media of the arterial wall. This degradation of the aortic wall can be attributed to risk factors such as tobacco smoking, sex, age, hypertension, chronic obstructive pulmonary disease, hyperlipidaemia, and family history of the disorder [1]. With the recent advancements in medicine, more AAAs are being detected than ever. Approximately 500,000 new cases are diagnosed each year worldwide resulting in 15,000 deaths per year in the USA alone [2]. Currently, the rupture risk of AAAs is regarded as a continuous function of aneurysm size, with surgical intervention decided based on the maximum diameter of the AAA. Most AAA repairs are performed when the diameter exceeds 50–60mm. It has been shown that maximum diameter may not be a reliable predictor of rupture, as smaller AAAs can also rupture. It is believed by many researchers that there is a need to review the determination of the timing of surgical intervention based solely on aneurysm diameter, and include other relevant risk factors. These additional risk factors could, for example, include, AAA wall stress, AAA expansion rate, degree of asymmetry, presence of intraluminal thrombus (ILT), and hypertension. The addition of these parameters may aid the surgical decision-making process. Shifting the current trend towards more encompassing assessment of AAA rupture potential may help reduce the morbidity and mortality rates associated with AAA repair. It was previously reported [3] that 82% of AAA ruptures occur on the posterior wall. In this research, the asymmetry of the AAA is examined, with respect to both peak wall stress and posterior wall stress, in ten realistic cases, and a resulting threshold factor is presented.

The Relationship Between Wall Stress and 3D Asymmetry in Repaired and Ruptured Abdominal Aortic Aneurysms

2010 ◽  
Author(s):  
Barry J. Doyle ◽  
Tim M. McGloughlin
Keyword(s):  
Risk Factors ◽  
Wall Stress ◽  
Posterior Wall ◽  
Aortic Aneurysms ◽  
Three Dimensions ◽  
Maximum Diameter ◽  
Patient Specific ◽  
Infrarenal Aorta ◽  
Abdominal Aortic ◽  
The Relationship

Abdominal aortic aneurysm (AAA) is a permanent dilation of the infrarenal aorta and is defined as having a diameter 50% greater than the original diameter. If left untreated, an AAA will continue to expand until rupture. The maximum diameter is currently the primary indicator of rupture-risk with AAAs > 5.5 cm deemed a likely to rupture. There have, however, been many reports identifying the inadequacies of the maximum diameter criterion to accurately determine the threat of rupture. It is believed by many researchers that there is a need to review the decision of surgical intervention based solely on aneurysm diameter, and rather include other relevant risk factors. These additional risk factors could, for example, include, AAA wall stress, AAA expansion rate, degree of asymmetry, presence of intraluminal thrombus (ILT), and hypertension. The addition of these parameters may aid the surgical decision-making process. A previous report by our group identified the relationship between asymmetry and posterior wall stress in patient-specific cases [1,2] and as over 80% of ruptures occur on the posterior wall [3] this finding may have significant clinical relevance. In this previous report, the study group was limited to 15 cases and asymmetry was only measured in the anterior-posterior plane. This current paper furthers this previous work by increasing the cohort to 40 cases of electively repaired AAAs and also examines 8 cases of ruptured AAAs. The methodology has been improved to now measure asymmetry in all three dimensions (3D).

The similarities and differences among patients with abdominal aortic aneurysms referred to a tertiary hospital and found at necropsy

Vascular ◽  
2014 ◽  
Vol 23 (4) ◽  
pp. 411-418 ◽  
Author(s):  
Erasmo S da Silva ◽  
Vitor C Gornati ◽  
Ivan B Casella ◽  
Ricardo Aun ◽  
Andre EV Estenssoro ◽  
...  
Keyword(s):  
Risk Factors ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Protective Factor ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Transverse Diameter ◽  
Abdominal Aortic ◽  
Tertiary Center

Objective To analyze the characteristics of patients with abdominal aortic aneurysms referred to a tertiary center and to compare with individuals with abdominal aortic aneurysm found at necropsy. Methods We have retrospectively analyzed the medical records of 556 patients with abdominal aortic aneurysm and 102 cases abdominal aortic aneurysm found at necropsy. Results At univariated analysis, hypertension, tobacco use and maximum diameter were significant risk factors for symptomatic aneurysm, while diabetes tended to be a protective factor for rupture. By logistic regression analysis, the largest transverse diameter was the only one significantly associated with abdominal aortic aneurysm rupture ( p < .0001, odds ratio 1.7, 95% confidence interval 1.481–1.951). Intact abdominal aortic aneurysm found at necropsy showed similarities with outpatients in relation to abdominal aortic aneurysm diameter and risk factors. Conclusion Intact abdominal aortic aneurysm at necropsy and at outpatients setting showed similarities that confirmed that abdominal aortic aneurysm repair is less offered to women, and they died more frequently with intact abdominal aortic aneurysm from other causes.

A Methodology for Verifying Abdominal Aortic Aneurysm Wall Stress

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Sergio Ruiz de Galarreta ◽  
Aitor Cazón ◽  
Raúl Antón ◽  
Ender A. Finol
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Experimental Testing ◽  
Wall Stress ◽  
Intraluminal Pressure ◽  
Maximum Diameter ◽  
Numerical Studies ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Geometric Factors

An abdominal aortic aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta of at least 1.5 times its normal diameter. Although the criterion of maximum diameter is still used in clinical practice to decide on a timely intervention, numerical studies have demonstrated the importance of other geometric factors. However, the major drawback of numerical studies is that they must be validated experimentally before clinical implementation. This work presents a new methodology to verify wall stress predicted from the numerical studies against the experimental testing. To this end, four AAA phantoms were manufactured using vacuum casting. The geometry of each phantom was subject to microcomputed tomography (μCT) scanning at zero and three other intraluminal pressures: 80, 100, and 120 mm Hg. A zero-pressure geometry algorithm was used to calculate the wall stress in the phantom, while the numerical wall stress was calculated with a finite-element analysis (FEA) solver based on the actual zero-pressure geometry subjected to 80, 100, and 120 mm Hg intraluminal pressure loading. Results demonstrate the moderate accuracy of this methodology with small relative differences in the average wall stress (1.14%). Additionally, the contribution of geometric factors to the wall stress distribution was statistically analyzed for the four phantoms. The results showed a significant correlation between wall thickness and mean curvature (MC) with wall stress.

Abstract 15501: Repeated Social Defeat Exaggerates Cacl2-induced Abdominal Aortic Aneurysm Expansion by Suppression of Periaortic Fibrosis in Tissue Repair Phase

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Hiroshi Kubota ◽  
Hiroyuki Yamada ◽  
Takeshi Sugimoto ◽  
Daisuke Miyawaki ◽  
Noriyuki Wakana ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Inflammatory Response ◽  
Social Defeat ◽  
Physical Contact ◽  
Maximum Diameter ◽  
Elastic Membrane ◽  
Infrarenal Aorta ◽  
Abdominal Aortic ◽  
External Elastic Membrane

Background and Objective: Depression is an independent risk factor of cardiovascular disease and significantly associated with the prevalence of abdominal aortic aneurysm (AAA). We investigated the impact of repeated social defeat (RSD) on AAA formation. Methods and Results: Eight-week-old male WT mice were exposed to RSD by housing with a larger CD-1 mouse in a shared cage. They were subjected to vigorous physical contact daily for 10 consecutive days. Control mice were housed in the same cage without physical contact. After social interaction test to confirm depressive-like behaviors, mice underwent application of 0.5M calcium chloride (CaCl 2 ) on the infrarenal aorta. At one-week, maximum diameter and circumference of external elastic membrane were comparable between the two groups. The number of F-4/80 and MMP-9-positive cells in immunofluorescent images were also comparable. Consistently, fluorescent image taken by IVIS revealed no difference in MMP activity, suggesting that acute inflammatory response was comparable between the two groups. In contrast, at two weeks, maximum diameter and circumference of external elastic membrane were significantly increased in defeated mice ( p < 0.01). Intriguingly, periaortic fibrotic area in aneurysmal portion was markedly decreased in defeated mice (12.5х10 3 μm 2 vs. 3.7х10 3 μm 2 , Control vs. Defeat, p < 0.01). Consistently, accumulation of α-SMA-positive cells in adventitia of aneurysmal portion was much lesser in defeated mice (876 cells/mm 2 vs. 319 cells/mm 2 , Control vs. Defeat, p < 0.05), whereas those in tunica media of non-aneurysmal portion did not show any difference between the two groups. LPS-induced iNOS gene and protein expressions in bone marrow-derived macrophages (BMDMs) were significantly decreased in defeated mice, whereas the TGF-β-induced phosphorylation of Smad2 and ERK1/2 in primary cultured aortic VSMCs were comparable between the two groups. Conclusions: Our findings demonstrate that RSD enhances AAA expansion by suppressing the periaortic fibrosis following inflammatory response, and suggest that decreased NO production from accumulated macrophages contributes to the reduced VSMCs proliferation and collagen deposition.

scholarly journals Increased Peak Wall Stress, but Not Maximum Diameter, Is Associated with Symptomatic Abdominal Aortic Aneurysm

2017 ◽  
Vol 54 (6) ◽  
pp. 706-711 ◽  
Author(s):  
Begoña Soto ◽  
Luis Vila ◽  
Jaime F. Dilmé ◽  
Jose R. Escudero ◽  
Sergi Bellmunt ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Wall Stress ◽  
Maximum Diameter ◽  
Abdominal Aortic ◽  
Peak Wall Stress

scholarly journals Prospective Ultrasound Screening of Men with Cerebrovascular Disease for Abdominal Aortic Aneurysms

2020 ◽  
pp. 145749692091726
Author(s):  
V. Vänni ◽  
J. Turtiainen ◽  
U. Kaustio ◽  
J. Toivanen ◽  
M. Rusanen ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Cerebrovascular Disease ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Infrarenal Aorta ◽  
Ultrasound Screening ◽  
Abdominal Aortic ◽  
Male Patients

Background: The prevalence of abdominal aortic aneurysms is higher in population with other vascular comorbidities, especially among men. Utility of screening among patients with cerebrovascular disease is unclear. Objective: To determine the prevalence of abdominal aortic aneurysm in male patients with diagnosed cerebrovascular disease manifested by transient ischemic attack or stroke. Material and Methods: Between May 2013 and May 2014, all consecutive male patients undergoing carotid ultrasound in single tertiary center with a catchment area of 179,000 inhabitants were evaluated for ultrasound screening of abdominal aortic aneurysm. Abdominal aortic aneurysm was defined as maximum diameter of infrarenal aorta 30 mm or more. Results: Of 105 (n = 105) consecutively evaluated male patients, only 69% (n = 72) were eligible for the study and underwent aortic screening. Reason for ineligibility was most often poor general medical condition (n = 29). Mean age of screened patients was 66 years (SD 9.8 years). Half of the screened patients suffered stroke (n = 36). The incidence of abdominal aortic aneurysm was 5.6% (n = 4). All found abdominal aortic aneurysms were small and did not require immediate surgical intervention. During a follow-up period of over 4 years, none of the aneurysms exhibited tendency for growth. Conclusion: The male population with cerebrovascular disease is comorbid and frail. Only, moderate prevalence of abdominal aortic aneurysms can be found in this subpopulation.

scholarly journals The Association of Wall Mechanics and Morphology: A Case Study of Abdominal Aortic Aneurysm Growth

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Christopher B. Washington ◽  
Judy Shum ◽  
Satish C. Muluk ◽  
Ender A. Finol
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Wall Stress ◽  
Aneurysm Rupture ◽  
Maximum Diameter ◽  
Least Squares Regression ◽  
Surveillance Period ◽  
Element Analysis ◽  
Abdominal Aortic ◽  
Peak Wall Stress

The purpose of this study is to evaluate the potential correlation between peak wall stress (PWS) and abdominal aortic aneurysm (AAA) morphology and how it relates to aneurysm rupture potential. Using in-house segmentation and meshing software, six 3-dimensional (3D) AAA models from a single patient followed for 28 months were generated for finite element analysis. For the AAA wall, both isotropic and anisotropic materials were used, while an isotropic material was used for the intraluminal thrombus (ILT). These models were also used to calculate 36 geometric indices characteristic of the aneurysm morphology. Using least squares regression, seven significant geometric features (p < 0.05) were found to characterize the AAA morphology during the surveillance period. By means of nonlinear regression, PWS estimated with the anisotropic material was found to be highly correlated with three of these features: maximum diameter (r = 0.992, p = 0.002), sac volume (r = 0.989, p = 0.003) and diameter to diameter ratio (r = 0.947, p = 0.033). The correlation of wall mechanics with geometry is nonlinear and reveals that PWS does not increase concomitantly with aneurysm diameter. This suggests that a quantitative characterization of AAA morphology may be advantageous in assessing rupture risk.

Analysis of Post-Operative Abdominal Aortic Aneurysm Repair: A Multi Patient-Specific Study

2009 ◽  
Author(s):  
David Molony ◽  
Michael Walsh ◽  
Tim McGloughlin
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Abdominal Aortic Aneurysm Repair ◽  
Maximum Diameter ◽  
Patient Specific ◽  
Invasive Technique ◽  
Infrarenal Aorta ◽  
Aneurysm Wall ◽  
Abdominal Aortic ◽  
Aneurysm Repair

Abdominal aortic aneurysm is an irreversible dilation of the infrarenal aorta, which if left untreated may rupture. Surgical intervention is usually necessary to prevent this outcome. The decision to operate is based on the maximum diameter of the aneurysm. Two types of treatment exist; these are open repair and endovascular repair (EVAR). Of concern here is EVAR, which is the minimally invasive technique of inserting a stent-graft into the site of the aneurysm in order to shield the aneurysm wall from the stresses of blood pressure.

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