Acoustic Radiation Force Impulse Imaging on ex vivo Abdominal Aortic Aneurysm Model

Tierney, Áine P.; Dumont, Douglas M.; Callanan, Anthony; Trahey, Gregg E.; McGloughlin, Timothy M.

doi:10.1016/j.ultrasmedbio.2010.02.018

Cited by 14 publications

(15 citation statements)

References 39 publications

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“…A recent study by Tierney et al 47 has explored the feasibility of using acoustic radiation force impulse (ARFI) imaging, which was developed at Duke University, to examine AAA mechanical properties. An artificially induced AAA model was analyzed using the ARFI technique to study the effects of AAA on vascular elastic pathology.…”

Section: The Future Of Aaa Rupture Riskmentioning

confidence: 99%

New Approaches to Abdominal Aortic Aneurysm Rupture Risk Assessment

McGloughlin

Doyle²

2010

ATVB

Self Cite

109

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Abstract-Abdominal aortic aneurysm (AAA) rupture remains a significant cause of death in the developed world. Current treatment approaches rely heavily on the size of the aneurysm to decide on the most appropriate time for clinical intervention and treatment. However, in recent years, several alternative rupture risk indicators have been proposed. This brief review examines some of these new approaches to AAA rupture risk assessment, from both numeric and experimental aspects and also what the future may hold for AAA rupture risk. Although numerically predicted wall stress, finite element analysis rupture index, rupture potential index, severity parameter, and geometric factors, such as asymmetry, have all been developed and show promise in possibly helping to predict AAA rupture risk, validation of these tools remains a significant challenge. Validation of biomechanics-based rupture indicators may be feasible by combining in vitro modeling of realistic AAA analogues with both retrospective and prospective monitoring and modeling of AAA cases. Peak wall stress is arguably the primary result obtained from numeric analyses; however, as the majority of ruptures occur in the posterior and posterior-lateral regions, the role of posterior wall stress has also recently been highlighted as potentially significant. It is also known that wall stress alone is not enough to cause rupture, as wall strength plays an equal role. Therefore, should a biomechanics-based rupture risk be implemented? There have been some significant steps, both numerically and experimentally, toward answering this and other questions relating to AAA rupture risk prediction, yet regardless of the efforts that are under way in several laboratories, the introduction of a numerically predicted rupture risk parameter into the clinicians' decision-making process may still be quite some time away. Key Words: aneurysms Ⅲ risk factors Ⅲ experimental modeling Ⅲ numerical modeling Ⅲ review Ⅲ rupture risk A pproximately 81 million people in the United States are currently living with one of the many forms of cardiovascular disease. Of this affected population, it is estimated that about 900 000 will die each year. Abdominal aortic aneurysm (AAA) is a dilation of the aorta beyond 50% of the normal vessel diameter, and it accounts for approximately 15 000 deaths per year in the United States. 1 AAA rupture risk is typically determined by size, and it has been shown that in the 5 years following AAA diagnosis, rupture occurs in approximately 2% of AAAs less than 4 cm in diameter and in more than 25% of AAAs larger than 5 cm. 2,3 Current clinical practice is to surgically repair large AAAs (diameter Ͼ5.5 cm) if the patient is fit for surgery or to regularly monitor (eg, every 6 months) smaller AAAs (diameter Ͻ5.5 cm) with ultrasound, with referral for surgery if the growth rate exceeds 1 cm/year or the diameter exceeds 5.5 cm. 3 However, surgeons need to compare the risk of rupture with the risk of repair, as it has been reported that only 25% of AAAs rupture in a...

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Section: The Future Of Aaa Rupture Riskmentioning

confidence: 99%

New Approaches to Abdominal Aortic Aneurysm Rupture Risk Assessment

McGloughlin

Doyle²

2010

ATVB

Self Cite

109

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“…The existence of residual stresses in plants, human tissues, insects and other animals has been the subject of many publications, including, for example, Nienhaus et al (2009), Vandiver and Goriely (2009), Holzapfel and Ogden (2010) and Tierney et al (2010). They are associated with tissue growth and remodelling and we refer to Taber (1995), Skalak et al (1996), Yeni et al (2002), Ambrosi et al (2008), Olsson and Klarbring (2008), Vandiver and Goriely (2009) and Wells and Walter (2010), and to the references therein, for a detailed discussion of various aspects of the development of residual stresses due to morphological changes in the tissues.…”

Section: Introductionmentioning

confidence: 99%

Modelling of residually stressed materials with application to AAA

Ahamed

Dorfmann

Ogden

2016

Journal of the Mechanical Behavior of Biomedical Materials

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Residual stresses are generated in living tissues by processes of growth and adaptation and they significantly influence the mechanical behaviour of the tissues. Thus, to effectively model the elastic response of the tissues relative to a residually stressed configuration the residual stresses need to be incorporated into the constitutive equations. The purposes of this paper are (a) to summarise a general elastic constitutive formulation that includes residual stress, (b) to specify the tensors needed for the three-dimensional implementation of the theory in a nonlinear finite element code, and (c) to use the theory and its implementation to evaluate the wall stress distribution in an abdominal aortic aneurysm (AAA) using patient specific geometry and material model parameters. The considered material is anisotropic with two preferred directions indicating the orientation of the collagen fibres in the aortic tissue. The method described in this paper is general and can be used, by specifying appropriate energy functions, to investigate other residually stressed biological systems.

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“…The opening angles for the normal aorta and elastase-treated rings showed an average 76% decrease from normal to elastase treated [n = 3] (Tierney et al, 2010).…”

Section: Ex Vivo Healthy and Elastase-treated Experimental Resultsmentioning

confidence: 99%

“…In brief, as described in our earlier work (Tierney et al, 2010), an excised porcine aorta (obtained from Sierra for Medical Science, P.O. Box 5692, Whittier, CA 90607-5692) was infused with porcine pancreatic elastase (LeeBioSolutions, St. Louis, Missouri; #345-10, concentration 20 Unit/milliliter) for 4 h. The aortas were flushed through with phosphate buffered solution (PBS).…”

Section: Development Of An Elastase (Experimental Aneurysm) Ex Vivo Mmentioning

confidence: 99%