Influence of size, shape and properties on the mechanics of axisymmetric saccular aneurysms

Kyriacou, S.K.; Humphrey, Jay D.

doi:10.1016/0021-9290(96)00010-3

Cited by 110 publications

(76 citation statements)

References 29 publications

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“…27 More recent work in our laboratory has allowed the improvement of AAA stress estimation technique by the incorporation of experimentally determined tissue anisotropy into our models. 47,59 Kyriacou and Humphrey showed that the stress distribution in cerebral aneurysms is markedly different when incorporating an anisotropic model versus a simplified isotropic model, 60 and we have made similar preliminary observations for AAA.…”

Section: Estimation Of Aaa Wall Stresssupporting

confidence: 78%

“…Similarly, Hunter et al made note of focal saccular outpouchings, or "blebs," found within the walls of some AAA and conjectured that they may represent sites of potential rupture. 67 Studies by our group 55 and others 60 indicate that such asymmetrical outpouchings result in focal stress concentrations. That the blebs were characterized by a decreased procollagen expression and decreased elastin content as compared with the adjacent AAA wall 68 again gives rise to the possibility that increased mechanical forces alter local ECM synthesis.…”

Section: Stress-mediated or Strain-mediated Wall Weakeningmentioning

confidence: 90%

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Biomechanical Determinants of Abdominal Aortic Aneurysm Rupture

Vorp

Geest

2005

ATVB

227

173

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Abstract-Rupture of abdominal aortic aneurysm (AAA) represents a significant clinical event, having a mortality rate of 90% and being currently ranked as the 13th leading cause of death in the US. The ability to reliably evaluate the susceptibility of a particular AAA to rupture on a case-specific basis could vastly improve the clinical management of these patients. Because AAA rupture represents a mechanical failure of the degenerated aortic wall, biomechanical considerations are important to understand this process and to improve our predictions of its occurrence. Presented here is an overview of research to date related to the biomechanics of AAA rupture. This includes a summary of results related to ex vivo and in vivo mechanical testing, noninvasive AAA wall stress estimations, and potential mechanisms of AAA wall weakening. We conclude with a demonstration of a biomechanics-based approach to predicting AAA rupture on a patient-specific basis, which may ultimately prove to be superior to the widely and currently used maximum diameter criterion. Key Words: abdominal aortic aneurysm Ⅲ biomechanics Ⅲ rupture Ⅲ strength Ⅲ stress A bdominal aortic aneurysm (AAA) is a focal enlargement of the infrarenal aorta, which occurs over a time course of several years. This condition is present in Ϸ2% of the elderly population, with Ϸ150 000 new cases diagnosed each year, and the incidence is increasing. 1,2 If left untreated, AAA will gradually expand until rupture; it is an event that carries a mortality rate of 90% and that is ranked as the 13th most common cause of death in the US. 3 Current AAA repair procedures are expensive and carry significant morbidity and mortality risks.Open repair of AAA is a major surgical procedure that requires patients to be hospitalized typically for 1 week and to recuperate at home for several more weeks. The mean postoperative mortality for elective repair is Ϸ5% and for emergency operations 47% (range 27% to 69%). 4 The major drawback of open repair is the compromised quality of life after surgery because of postoperative pain, the prolonged recovery period, and the high costs associated with both the surgery and the recovery.An alternative approach that avoids the extensive tissue dissection associated with open repair is the minimally invasive endovascular repair procedure. The potential advantages of endovascular AAA repair include reductions in mortality, morbidity, blood loss, hospital stay, intensive careOriginal

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Section: Estimation Of Aaa Wall Stresssupporting

confidence: 78%

Section: Stress-mediated or Strain-mediated Wall Weakeningmentioning

confidence: 90%

Biomechanical Determinants of Abdominal Aortic Aneurysm Rupture

Vorp

Geest

2005

ATVB

227

173

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“…It was long thought that these lesions could enlarge rapidly due to structural instabilities, namely, a limit point instability or resonance (19)(20)(21)(22). Whereas these studies assumed linear or rubber-like properties of the wall, more appropriate nonlinear analyses suggest that such instabilities are unlikely (23,24). Rather, ISAs appear to enlarge via mechano-regulated growth and remodeling (G&R) processes common to diverse vascular adaptations (25,26).…”

Section: Natural History Intracranial Saccular Aneurysm (Isa)mentioning

confidence: 99%

“…Failure mechanisms remain unknown, but rupture usually occurs at the fundus (pole) despite the neck often being thinner (2,41). Although this was long perplexing, finite element calculations suggest that the maximum biaxial stresses typically occur near the fundus, where intramural shear stress is small (23,(42)(43). For this reason, it appears that a rupture criterion should be based on tensile, not shearing, stresses or strains.…”

Section: Natural History Intracranial Saccular Aneurysm (Isa)mentioning

confidence: 99%

“…From the perspective of mechanics, however, shape and wall thickness are more important determinants of stress in distended membranes than is overall size (23,43,52). Ujiie et al (53) reported that 59% of ISAs are round, 24% oval, and 22% bar-like, but there has been little attempt to correlate rupture potential with specific shapes.…”

Section: Natural History Intracranial Saccular Aneurysm (Isa)mentioning

confidence: 99%

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Intracranial and Abdominal Aortic Aneurysms: Similarities, Differences, and Need for a New Class of Computational Models

Humphrey

Taylor

2008

Annu. Rev. Biomed. Eng.

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269

238

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Intracranial and abdominal aortic aneurysms result from different underlying disease processes and exhibit different rupture potentials, yet they share many histopathological and biomechanical characteristics. Moreover, as in other vascular diseases, hemodynamics and wall mechanics play important roles in the natural history and possible treatment of these two types of lesions. The goals of this review are twofold: first, to contrast the biology and mechanics of intracranial and abdominal aortic aneurysms to emphasize that separate advances in our understanding of each disease can aid in our understanding of the other disease, and second, to suggest that research on the biomechanics of aneurysms must embrace a new paradigm for analysis. That is, past biomechanical studies have provided tremendous insight but have progressed along separate lines, focusing on either the hemodynamics or the wall mechanics. We submit that that there is a pressing need to couple in a new way the separate advances in vascular biology, medical imaging, and computational biofluid and biosolid mechanics to understand better the mechanobiology, pathophysiology, and treatment of these lesions, which continue to be responsible for significant morbidity and mortality. We shall refer to this needed new class of computational tools as Fluid-Solid-Growth (FSG) Models.

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Vascular Mechanics

Moore

Bedoya

Meyer

et al. 2006

Wiley Encyclopedia of Biomedical Engineering

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The vascular system provides the crucial task of delivering oxygen and nutrients to all of the body's tissues. The proper functioning of the system is made possible by very specific mechanical characteristics that result from the combination of different materials. Vessel walls contain crucial cellular elements that themselves require nutrients and strongly affect the mechanical performance. Arterial mechanics are important in the formation and progression of a number of diseases. In turn, the mechanical properties are affected by disease development. Research in this field is richly challenging because of the complexity of the mechanics and the interaction with biological function.

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Influence of size, shape and properties on the mechanics of axisymmetric saccular aneurysms

Cited by 110 publications

References 29 publications

Biomechanical Determinants of Abdominal Aortic Aneurysm Rupture

Biomechanical Determinants of Abdominal Aortic Aneurysm Rupture

Intracranial and Abdominal Aortic Aneurysms: Similarities, Differences, and Need for a New Class of Computational Models

Vascular Mechanics

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