Invited commentary

Abstract

Abdominal aortic aneurysm diameter is the primary factor that has been used to direct aneurysm therapy. Aortic morphologic characteristics have failed to have a demonstrable impact on clinical decision-making for several reasons. Foremost, the morphologic assessments must be readily available to clinicians, inexpensive, and easy to measure and have clinically defined thresholds that direct care. However, defining aneurysm morphologic features does have additional value beyond directing therapy. Clinicians, researchers, and engineers alike are constantly exploring the boundary conditions on which to base new medical treatments; these morphologic features can help direct new therapies. Advent and adoption of endovascular aneurysm repair have limited the opportunity to examine aortic wall tissue. In the current manuscript, Barrett et al monopolize the opportunity to subject harvested aortic aneurysm wall to mechanical stretch forces that parallel physiologic conditions. It is intuitive that degraded aortic wall will demonstrate varying degrees of stiffness and response to stress. However, it is uncertain which morphologic features affect those features. The authors reinforce the assumption that the aortic wall is subjected to extreme asymmetry when uniform stress is applied. Regions of high stiffness, marked by calcium deposition, are surrounded by vulnerable regions of low stiffness. The regions surrounding calcium are subjected to greater degrees of deformation, which translates to increased strains; in some regions surrounding calcium, the wall demonstrated two to four times the strain compared with reference regions. In addition, the authors demonstrated that stiff intraluminal thrombus also alters surrounding aortic wall mechanical properties similar to that of calcium. Regions of high strain also correlated with wall thinning and stretching visualized on electron microscopy. Interestingly, aortic diameter did not correlate with changes in aortic wall mechanics. Routine clinical imaging readily detects calcium burden within the aortic wall, and each patient demonstrates varying degrees of calcium within the aneurysm. The localized variation in aortic wall mechanics may provide additional information to identify patients at risk for rupture. In the future, this information may be used to adjust surveillance or to offer therapy, but for now, it will provide another boundary condition to better explain aneurysm wall mechanics and resultant aneurysm behavior. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. On the influence of wall calcification and intraluminal thrombus on prediction of abdominal aortic aneurysm ruptureJournal of Vascular SurgeryVol. 67Issue 4PreviewParameters other than maximum diameter that predict rupture of abdominal aortic aneurysms (AAAs) may be helpful for risk-benefit analysis in individual patients. The aim of this study was to characterize the biomechanical-structural characteristics associated with AAA walls to better identify the related mechanistic variables required for an accurate prediction of rupture risk. Full-Text PDF Open Archive