On the Uptake of Ultrasmall Superparamagnetic Particles of Iron Oxide and Biomechanical Wall Stress in Abdominal Aortic Aneurysms

2012 ◽  
Author(s):  
Barry Doyle ◽  
Jennifer Richards ◽  
Scott Semple ◽  
Tom MacGillivray ◽  
Calum Gray ◽  
...  
Keyword(s):  
Wall Stress ◽  
Inflammatory Cells ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Western World ◽  
Important Work ◽  
General Belief ◽  
Abdominal Aortic ◽  
The Us ◽  
Improved Methods

Abdominal aortic aneurysms (AAAs) remain a significant cause of death in the Western world with over 15,000 deaths per year in the US linked to AAA rupture. There is a general belief among the clinical and engineering community that improved methods of risk prediction are needed. The growth and expansion of AAAs over time is thought to be associated with the mechanobiological interactions within the diseased AAA wall. The stresses and strains induced in the wall by the internal blood pressure trigger increased protease activity and turnover of the extracellular matrix (ECM), thus enabling degradation and expansion of the wall. Inflammatory cells also control collagen synthesis and inflammation can reduce the tensile strength of the wall, thus contributing to the likelihood of rupture. Recently, important work by Richards et al. [1] showed that AAAs with specific sites of focal inflammation have threefold higher growth rates than AAAs with non-specific inflammation.

Use of the Photoelastic Method to Determine the Wall Stress in Realistic Abdominal Aortic Aneurysm Models

2011 ◽  
Author(s):  
Barry J. Doyle ◽  
Anthony Callanan ◽  
John Killion ◽  
Timothy M. McGloughlin
Keyword(s):  
Wall Stress ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Patient Specific ◽  
Western World ◽  
Photoelastic Method ◽  
Element Analysis ◽  
Abdominal Aortic ◽  
The Us ◽  
Numerical Tools

Abdominal aortic aneurysms (AAAs) remain a significant cause of death in the Western world with over 15,000 deaths per year in the US linked to AAA rupture. Recent research [1] has questioned the use of maximum diameter as a definitive risk parameter as it is now believed that alternative factors may be important in rupture-prediction. Wall stress was shown to be a better predictor than diameter of rupture [1], with biomechanics-based rupture indices [2,3] and asymmetry also reported to have potential clinical applicability [4]. However, the majority of numerical methods used to form these alternative rupture parameters are without rigorous experimental validation, and therefore may not be as accurate as believed. Validated experiments are required in order to convince the clinical community of the worth of numerical tools such as finite element analysis (FEA) in AAA risk-prediction. Strain gauges have been used in the past to determine the strain on an AAA [5], however, the photoelastic method has also proved to be a useful tool in AAA biomechanics [6]. This paper examines the approach using three medium-sized patient-specific AAA cases at realistic pressure loadings.

Development and 3D Finite Element Implementation of a Multiaxial Constitutive Relation for Abdominal Aortic Aneurysms

2004 ◽  
Author(s):  
Jonathan Vande Geest ◽  
Ajay Bohra ◽  
Wei Sun ◽  
Elena Di Martino ◽  
Michael S. Sacks ◽  
...  
Keyword(s):  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Western World ◽  
Infrarenal Aorta ◽  
3D Finite Element ◽  
Finite Element Implementation ◽  
The Past ◽  
Abdominal Aortic ◽  
The Us ◽  
Significant Disease

Abdominal aortic aneurysm (AAA), a localized dilation of the infrarenal aorta, represents a significant disease in the western population. There are approximately 200,000 patients in the US and 500,000 patients worldwide diagnosed with AAAs every year (Bosch, et al. 2001), and rupture of AAAs currently ranks as the 13th leading cause of death in the US. (Silverberg and Lubera 1987) In the past 30 years, the diagnosis of AAA has tripled in the Western world, and this will likely increase in the coming years as the average age of the population is increasing. (Bosch, et al. 2001)

Discrimination of Vessel Wall Components of Abdominal Aortic Aneurysms by Multi-Contrast MRI

2008 ◽  
Author(s):  
Evelyne van Dam ◽  
Marcel Rutten ◽  
Frans van de Vosse
Keyword(s):  
Vessel Wall ◽  
Computational Models ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Western World ◽  
Atherosclerotic Plaques ◽  
Abdominal Aortic ◽  
Wall Components

Rupture of an abdominal aortic aneurysm (AAA) is a major cause of death in the Western world. When the AAA is diagnosed timely, rupture can be prevented by conventional surgical or by endovascular repair. To date, the decision to operate is based on geometry alone, but it has already been suggested that wall stress would be a better predictor [2]. Patient specific computational models have been developed to calculate wall stress [2; 5; 9; 8; 10]. In these models, the AAA wall is assumed to be homogeneous. Patient-specific inhomogeneities such as atherosclerotic plaques and calcifications have large effects on the maximum wall stress and wall stress distribution [6; 7]. Histological examination is not feasible for determining wall composition of patients.

scholarly journals Mechanical and geometrical determinants of wall stress in abdominal aortic aneurysms: A computational study

PLoS ONE ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. e0192032 ◽  
Author(s):  
Dara Azar ◽  
Donya Ohadi ◽  
Alexander Rachev ◽  
John F. Eberth ◽  
Mark J. Uline ◽  
...  
Keyword(s):  
Computational Study ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Abdominal Aortic

Pulsatile Flow in Fusiform Models of Abdominal Aortic Aneurysms: Flow Fields, Velocity Patterns and Flow-Induced Wall Stresses

2004 ◽  
Vol 126 (4) ◽  
pp. 438-446 ◽  
Author(s):  
Robert A. Peattie ◽  
Tiffany J. Riehle ◽  
Edward I. Bluth
Keyword(s):  
Shear Stress ◽  
Pulsatile Flow ◽  
Maximum Shear Stress ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Flow Fields ◽  
Aortic Aneurysms ◽  
Abdominal Aortic ◽  
Risk Of Rupture

As one important step in the investigation of the mechanical factors that lead to rupture of abdominal aortic aneurysms, flow fields and flow-induced wall stress distributions have been investigated in model aneurysms under pulsatile flow conditions simulating the in vivo aorta at rest. Vortex pattern emergence and evolution were evaluated, and conditions for flow stability were delineated. Systolic flow was found to be forward-directed throughout the bulge in all the models, regardless of size. Vortices appeared in the bulge initially during deceleration from systole, then expanded during the retrograde flow phase. The complexity of the vortex field depended strongly on bulge diameter. In every model, the maximum shear stress occurred at peak systole at the distal bulge end, with the greatest shear stress developing in a model corresponding to a 4.3 cm AAA in vivo. Although the smallest models exhibited stable flow throughout the cycle, flow in the larger models became increasingly unstable as bulge size increased, with strong amplification of instability in the distal half of the bulge. These data suggest that larger aneurysms in vivo may be subject to more frequent and intense turbulence than smaller aneurysms. Concomitantly, increased turbulence may contribute significantly to wall stress magnitude and thereby to risk of rupture.

scholarly journals Peak wall stress measurement in elective and acute abdominal aortic aneurysms

2008 ◽  
Vol 47 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Michael S. Heng ◽  
Michael J. Fagan ◽  
Jason W. Collier ◽  
Grishma Desai ◽  
Peter T. McCollum ◽  
...  
Keyword(s):  
Stress Measurement ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Abdominal Aortic ◽  
Peak Wall Stress

A Relation Between Particle Hemodynamics and Intraluminal Thrombus Formation in Abdominal Aortic Aneurysms

2009 ◽  
Author(s):  
Christopher A. Basciano ◽  
Julie H. Y. Ng ◽  
Ender A. Finol ◽  
Clement Kleinstreuer
Keyword(s):  
Particle Deposition ◽  
Thrombus Formation ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Blood Proteins ◽  
Intraluminal Thrombus ◽  
Abdominal Aortic ◽  
Cellular Debris ◽  
The Us ◽  
Normal Diameter

Abdominal aortic aneurysms (AAAs) are local dilations of the aorta below the renal arteries where the lumen diameter is ≥ 1.5 times the normal diameter of the healthy blood vessel. Ruptured aneurysms are the 13th leading cause of death in the US [1]. In approximately 75% of all AAAs, a particle-deposition layer forms adjacent to the arterial wall within the lumen called the intra-luminal thrombus (ILT). The thrombus composition has been shown to be a fibrin structure composed of blood cells, platelets, blood proteins, and other cellular debris [2]. Additionally, Yamazumi et al. [3] have presented data that suggest AAA morphology is associated with an elevated state of blood coagulation and fibrinolysis within the aneurysm.

Improvements in Rupture Prediction of Abdominal Aortic Aneurysms Using Local Mechanical Property Estimation Obtained From ECG-Gated Computed Tomography

2010 ◽  
Author(s):  
Áine Tierney ◽  
Anthony Callanan ◽  
Tim M. McGloughlin
Keyword(s):  
Computed Tomography ◽  
Abdominal Aortic Aneurysms ◽  
Common Type ◽  
Aortic Aneurysms ◽  
Diagnostic Tools ◽  
The Past ◽  
Property Estimation ◽  
Abdominal Aortic ◽  
The Us ◽  
Local Mechanical Property

Cardiovascular disease concerns any disease which affects the heart or blood vessels. Aneurysms account for a significant portion of these cardiovascular diseases. The most common type of aneurysm is abdominal aortic aneurysm (AAA) which affects up to 5% of the population over the age of 55. AAA is a focal balloon like dilation of the terminal aorta that occurs gradually over a span of years [1]. There are approximately 200,000 patients in the US and 500,000 patients worldwide diagnosed with AAA each year [2]. The incidences of AAA’s has increased largely during the past two decades due in part to the aging demographic, the rise in the number of smokers, the introduction of screening programmes and improved diagnostic tools [3].

Wall Stress Reduction in Abdominal Aortic Aneurysms as a Result of Polymeric Endoaortic Paving

2011 ◽  
Vol 39 (6) ◽  
pp. 1680-1689 ◽  
Author(s):  
John H. Ashton ◽  
Avinash Ayyalasomayajula ◽  
Bruce R. Simon ◽  
Jonathan P. Vande Geest
Keyword(s):  
Stress Reduction ◽  
Wall Stress ◽  
Abdominal Aortic Aneurysms ◽  
Aortic Aneurysms ◽  
Abdominal Aortic

Development of a Thrombus Mimic in Abdominal Aortic Aneurysms

2007 ◽  
Author(s):  
John H. Ashton ◽  
Jonathan P. Vande Geest
Keyword(s):  
United States ◽  
Cause Of Death ◽  
Growth And Development ◽  
Abdominal Aortic Aneurysms ◽  
The United States ◽  
Aortic Aneurysms ◽  
Western World ◽  
Abdominal Aortic ◽  
Significant Disease

Abdominal aortic aneurysms (AAAs) represent a significant disease in the western world as rupture of AAA is currently the 15th leading cause of death in the United States [1,2]. The rate of incidence of this disease is also thought to be increasing given the aging population. While AAA rupture is attributed to the gradual weakening of the wall, the mechanisms of aneurysm initiation, growth, and development remain relatively unclear. The role of biomechanics in the diagnosis and prevention of AAA rupture has been reported [3].

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