The Association Between Curvature and Rupture in a Murine Model of Abdominal Aortic Aneurysm and Dissection

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 360(o)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.

Automated summary

This study investigated the predictive role of surface curvature in AAA failure under supra-physiological inflation pressures. The findings revealed strong associations between burst pressure and curvature indices, emphasizing the importance of shape in experimental AAA models.