Background: Two-dimensional (2D) echocardiography is one of the most feasible, noninvasive methods for assessing the aortic diameter and biomechanical changes. We studied possible interfaces between noninvasive biomechanical and speckle-tracking (ST) echocardiographic data from dilated aortas.
Methods: Altogether, 44 patients with dilative pathology of ascending aorta (DPAA) were compared with subjects without ascending aortic dilation (diameter <40 mm). DPAA patients formed two groups based on diameter size: group 1, ≤45 mm diameter; group 2, >45 mm. Conventional and 2D-ST echocardiography were performed to evaluate peak longitudinal strain (LS), longitudinal (LD) and transverse (TD) displacement, and longitudinal velocity (VL). Aortic strain, distensibility, elastic modulus, stiffness index β of Valsalva sinuses and ascending aorta were also evaluated. SPSS version 20 was used for all analyses.
Results: All linear diameters of the ascending aorta were increased in group 2 (>45 mm diameter) (p < 0.05). LD of the anterior aortic wall (p < 0.05) and TD of both aortic walls (p < 0.001) were least in group 2. VL of the posterior and anterior walls diminished in group 2 (p = 0.01). Aortic strain and distensibility were least (p = 0.028 and p = 0.001, respectively) and elastic modulus and stiffness index β values were greatest in group 2, although without statistical significance.
Conclusions: Ascending aortas of both DPAA groups had reduced elasticity and increased stiffness. The greatest changes in biomechanical parameters occurred in ascending aortas >45 mm. Longitudinal ascending aortic wall motion was mostly impaired in patients with aortas >45 mm (i.e., anterior aortic wall LD, VL of the posterior and anterior walls. TD of the posterior and anterior aortic walls was significantly lower in >45 mm aortic diameter patients. TD of 5.2 mm could predict aortic dilation >45 mm (area under the curve 0.76, p < 0.001, confidence interval 0.65-0.87; sensitivity 87%; specificity 63%). Greater aortic dilation is associated with reduced aortic stiffness parameters and increased elastic modulus and stiffness index β. Lower LD and LS were associated with less aortic strain and distensibility. There were no significant differences in 2D-ST echocardiographic or stiffness parameters between patients with tricuspid or bicuspid aortic valves.
Keywords: Ascending aorta; Biomechanics of aorta; Speckle-tracking echocardiography; Stiffness.