Anisotropy, heterogeneity, and limited sex differences in aortic suture retention

Suture-line complications following aortic graft repair can have life-threatening consequences. To mitigate the clinical risk of anastomotic dehiscence, vascular prostheses are evaluated using the suture retention test defined by ISO 7198:2016. While appropriate for synthetic grafts under controlled loading conditions, this standard does not account for the nonlinear, anisotropic, and heterogeneous mechanical behavior of native elastic arteries, their composite microstructure, or variability among animal models used in preclinical testing.

We applied ISO suture pull-to-failure testing (N = 304) in a porcine aortic model to quantify regional, positional, directional, and sex-based variability in suture retention. Mechanical outcomes were analyzed using linear mixed models and unpaired t-tests, while relationships between tissue mechanics and extracellular matrix organization were evaluated using Spearman correlation analysis.

Longitudinal and circumferential position, as well as pull direction, significantly affected tissue-normalized maximum force, stiffness, and work, and tissue displacement at failure. Sex-dependent differences in suture retention were also observed, although to a lesser extent and only in the circumferential direction. Collagen fiber alignment emerged as the primary microstructural determinant of suture retention behavior, followed by elastin area fraction.

This study establishes a histomechanistic link between local aortic microstructure and suture retention in a porcine model. These findings may be used to support improved vascular prosthesis and suture design, reduce graft-host compliance mismatch, and inform clinical suturing strategies.