Characterization of the stress-strain relationship of the abdominal aortic wall in vivo

Abstract

We hereby propose a new method to determine the regionally passive, elastic, stress-strain relationship of the normal murine abdominal aorta in vivo. The circumferential stress-strain relationship was assessed through Laplace's law, a small deformation framework and a relationship between luminal pressure and diameter variation. The regional diameter variation of the murine abdominal aortas was obtained using a cross-correlation technique on radiofrequency (RF) signals at the extremely high frame rate of 8 kHz. The luminal pressure variation was measured by an ultra-miniature pressure catheter over one cardiac cycle. The change of slope of the stress-strain curve was noticed, which was the contribution of elastin and engaged collagen fibers. The stress-strain relationships before and after this transition was assumed to be linear. Three Young's moduli of the aortic wall were characterized in six mice in vivo: (1) elastin, (2) elastin-collagen and (3) engaged collagen fibers, which were equal to 91.6±26.5, 229.0±80.4 and 137.5±65.6 kPa, respectively. The proposed methodology thus allowed for noninvasive mapping of the mechanical properties of its constituents in vivo. ©2009 IEEE.