Background: The characteristics of aortic elasticity are unclear in children with connective tissue disorders (CTDs) such as Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS), especially in those with a non-dilated aortic root (AoR). This study evaluated the aortic elasticity properties of pediatric MFS and LDS patients with either dilated or non-dilated AoR.Methods and Results:The 31 children with MFS or LDS were classified into dilated (Z score of AoR diameter ≥2.5; n=17) or non-dilated (Z score of AoR diameter <2.5; n=14) AoR groups and compared with controls. Using transthoracic echocardiography, we analyzed the aortic elasticity parameters of distensibility, strain, and stiffness index at the levels of the AoR, sinotubular junction, ascending aorta, and descending aorta. Aortic distensibility and strain were significantly lower in both test groups than in controls at the AoR level. The Z score of AoR diameter significantly correlated with aortic distensibility (R=-0.63, P<0.001), strain (R=-0.54, P=0.002), and stiffness index (R=0.52, P=0.002) in the patients' groups. Multivariate analysis revealed that aortic distensibility and the type of CTD were independently associated with AoR dilatation.
Conclusions: Aortic elasticity at the level of the AoR may be decreased in children with MFS or LDS even before AoR dilatation progresses. Less aortic distensibility and CTD type are considered important parameters in estimating AoR dilatation in these patients. (Circ J 2016; 80: 2369-2375).