Elastic properties of the ascending aorta in healthy children and adolescents. Age-related reference values for aortic wall stiffness and distensibility obtained on M-mode echocardiography.
Compliance of the aorta is important in maintaining normal cardiovascular physiology. Pathological conditions can induce changes in elastic properties, having profound effects on their prognosis. The aim of this study was to establish age-related reference values for distensibility and wall stiffness index of the ascending aorta.A total of 165 normal subjects (mean age, 11.92±4.0 years) were investigated on transthoracic echocardiography. Ascending aortic diameter was recorded in M-mode above the sinotubular junction. Blood pressure was measured simultaneously at the right arm. Aortic pulse pressure, distensibility and aortic wall stiffness index were calculated offline. Distensibility decreased significantly with age (r=-0.462, P<0.001); the regression line indicated an average decrease of 5.1 10(-3)kPa(-1) (95% confidence interval [CI]: 3.9-6.8 10(-3)kPa(-1)) per year. Significant correlations could be found between distensibility and weight, height, body surface area (BSA) and body mass index (BMI) (P<0.001). Stiffness index increased significantly with age (r=0.399, P<0.001); the regression line indicated an average increase of 0.066 (95% CI: 0.047-0.085) per year; significant correlations could be found between wall stiffness index and weight, height, BSA and BMI (P<0.001). The 2.5th and 97.5th percentiles of the distribution of distensibility and stiffness index related to age, weight, height, BSA and BMI were calculated.Normal values of arterial elastic properties throughout childhood and adolescence have been provided, and might serve as a reference for individuals with cardiovascular and metabolic disease.