Aneurysm Wall Stress and Tendency to Rupture are Features of Physical Wall Properties: An Experimental Study

Purpose:To use bench top techniques to examine the biophysical phenomena affecting the risk of abdominal aortic aneurysm (AAA) rupture relative to the physical properties of the aneurysm sac.Methods:Three latex AAAs with different wall elasticities were tested in a validated pulsatile flow model (PFM). Strain gauges were wired to each AAA model at the neck, inflection point, and at the maximum diameter. In initial studies, the influence of pressurization and the mechanical properties of AAA wall stress were evaluated. In subsequent studies, the latex AAAs were excluded with a tube graft and retested in the PFM. After creation of either a type I or II endoleak of known size and pressure, the systemic/intrasac pressure and the AAA wall stress were measured.Results:Each model had a complex wall-stress pattern comprising radial, longitudinal, and shear components. The peak wall stress at any point, in the presence of systemic pressurization or endoleak pressure, only reached 1% of the failure strength. In an ...