The Association Between Curvature and Rupture in a Murine Model of Abdominal Aortic Aneurysm and Dissection
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SP ISS: EXPERIMENTAL ADVANCES IN CARDIOVASCULAR BIOMECHANICS
The Association Between Curvature and Rupture in a Murine Model of Abdominal Aortic Aneurysm and Dissection B.A. Lane 1
&
M.J. Uline 1,2
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X. Wang 3 & T. Shazly 1,4 & N.R. Vyavahare 3
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J.F. Eberth 1,5
Received: 27 January 2020 / Accepted: 18 August 2020 # Society for Experimental Mechanics 2020
Abstract Background Mouse models of abdominal aortic aneurysm (AAA) and dissection have proven to be invaluable in the advancement of diagnostics and therapeutics by providing a platform to decipher response variables that are elusive in human populations. One such model involves systemic Angiotensin II (Ang-II) infusion into low density-lipoprotein receptor-deficient (LDLr −/−) mice leading to intramural thrombus formation, inflammation, matrix degradation, dilation, and dissection. Despite its effectiveness, considerable experimental variability has been observed in AAAs taken from our Ang-II infused LDLr−/− mice (n = 12) with obvious dissection occurring in 3 samples, outer bulge radii ranging from 0.73 to 2.12 mm, burst pressures ranging from 155 to 540 mmHg, and rupture location occurring 0.05 to 2.53 mm from the peak bulge location. Objective We hypothesized that surface curvature, a fundamental measure of shape, could serve as a useful predictor of AAA failure at supra-physiological inflation pressures. Methods To test this hypothesis, we fit well-known biquadratic surface patches to 360o micro-mechanical test data and used Spearman’s rank correlation (rho) to identify relationships between failure metrics and curvature indices. Results We found the strongest associations between burst pressure and the maximum value of the first principal curvature (rho = −0.591, p-val = 0.061), the maximum value of Mean curvature (rho = −0.545, p-val = 0.087), and local values of Mean curvature at the burst location (rho = −0.864, p-val = 0.001) with only the latter significant after Bonferroni correction. Additionally, the surface profile at failure was predominantly convex and hyperbolic (saddle-shaped) as indicated by a negative sign in the Gaussian curvature. Findings reiterate the importance of shape in experimental models of AAA. Keywords Mouse models of Aortopathy . Differential geometry . Curvature
Introduction Abdominal aortic aneurysms (AAA) are life-threatening conditions with diverse etiologies all characterized by a 1.5-fold
* J.F. Eberth [email protected] 1
Biomedical Engineering Program, University of South Carolina, 301 Main Street, Columbia, South Carolina 29208, USA
2
Chemical Engineering Department, University of South Carolina, 301 Main Street, Columbia, South Carolina 29208, USA
3
Bioengineering Department, Clemson University, 301 Rhodes Research Center, Clemson, South Carolina 29634, USA
4
Mechanical Engineering Department, University of South Carolina, 300 Main Street, Columbia, South Carolina 29208, USA
5
Cell Biology and Anatomy Department, University of South Carolina School of Medicine, Building 1, Room C-36, Columbia,
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