Abdominal aortic aneurysm (AAA) is a focal enlargement of the infrarenal aorta. If left untreated, AAA will gradually expand until rupture, an event that carries a mortality rate of 90%. 15,000 Americans die each year from AAA rupture, making it the 13th most common cause of death in the US. Associated with repair of AAA are significant costs and risks to the patient. Thus, it is important to determine when the risk of rupture justifies the risks associated with surgery. The ability to reliably evaluate the susceptibility of a particular AAA to rupture could vastly improve the clinical management of these patients, as there presently exists no such reliable evaluation criterion. AAA rupture occurs when the mechanical stress acting on the aneurysm wall locally exceeds its failure strength. The greater the wall stress-to-wall strength ratio for a particular AAA, the greater the likelihood of rupture. We therefore believe that careful consideration of the Rupture Potential Index (RPI) would lead to an improved assessment of the propensity for rupture of AAA on a patient-specific basis. The RPI is defined as the locally acting wall stress divided by the local wall strength. As the RPI increases, so too does the possibility of AAA rupture. Our original grant, for which the current proposal serves as a competing renewal application, allowed us to develop methods to noninvasively determine the RPI distribution for AAA on a patient-specific basis. The working hypothesis of this proposal is that the RPI - i.e., the peak ratio of local wall stress to local wall strength - is a better predictor of AAA rupture than either the maximum aneurysm diameter or peak wall stress alone. To address this hypothesis, we will execute the following three specific aims: 1) Perform an """"""""in-vitro validation"""""""" of our RPI technique using physical (i.e., custom-fabricated polymer) models of patient-specific AAA;2) Perform a """"""""retrospective clinical validation"""""""" of our RPI technique by analyzing existing data from patients who underwent AAA rupture (or were symptomatic prior to repair) and comparing to that from patients who's AAA did not rupture;and 3) Perform a """"""""prospective clinical validation"""""""" of our RPI technique by collecting and analyzing data from patients with AAA followed over time in order to evaluate the time-course of RPI and its correlation with unfavorable clinical outcome. Successful validation of this novel, innovative, computationally-based, noninvasive method would allow an important paradigm shift to occur in AAA patient management and care by defining a new, more reliable criterion on which decisions to repair AAA will be based. This would greatly improve the clinical management for those afflicted with this disease.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Bioengineering, Technology and Surgical Sciences Study Section (BTSS)
Program Officer
Goldberg, Suzanne H
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pittsburgh
Schools of Medicine
United States
Zip Code
Pichamuthu, Joseph E; Phillippi, Julie A; Cleary, Deborah A et al. (2013) Differential tensile strength and collagen composition in ascending aortic aneurysms by aortic valve phenotype. Ann Thorac Surg 96:2147-54
Doyle, Barry J; Killion, John; Callanan, Anthony (2012) Use of the photoelastic method and finite element analysis in the assessment of wall strain in abdominal aortic aneurysm models. J Biomech 45:1759-68
McGloughlin, Timothy M; Doyle, Barry J (2010) New approaches to abdominal aortic aneurysm rupture risk assessment: engineering insights with clinical gain. Arterioscler Thromb Vasc Biol 30:1687-94
Corbett, T J; Doyle, B J; Callanan, A et al. (2010) Engineering silicone rubbers for in vitro studies: creating AAA models and ILT analogues with physiological properties. J Biomech Eng 132:011008
Doyle, Barry J; Cloonan, Aidan J; Walsh, Michael T et al. (2010) Identification of rupture locations in patient-specific abdominal aortic aneurysms using experimental and computational techniques. J Biomech 43:1408-16
Doyle, B J; Grace, P A; Kavanagh, E G et al. (2009) Improved assessment and treatment of abdominal aortic aneurysms: the use of 3D reconstructions as a surgical guidance tool in endovascular repair. Ir J Med Sci 178:321-8
Doyle, Barry J; Corbett, Timothy J; Callanan, Anthony et al. (2009) An experimental and numerical comparison of the rupture locations of an abdominal aortic aneurysm. J Endovasc Ther 16:322-35
Doyle, Barry J; Callanan, Anthony; Burke, Paul E et al. (2009) Vessel asymmetry as an additional diagnostic tool in the assessment of abdominal aortic aneurysms. J Vasc Surg 49:443-54
Doyle, Barry J; Corbett, Timothy J; Cloonan, Aidan J et al. (2009) Experimental modelling of aortic aneurysms: novel applications of silicone rubbers. Med Eng Phys 31:1002-12
Doyle, B J; Morris, L G; Callanan, A et al. (2008) 3D reconstruction and manufacture of real abdominal aortic aneurysms: from CT scan to silicone model. J Biomech Eng 130:034501

Showing the most recent 10 out of 26 publications