[Non-invasive measurement of the elastic properties of the abdominal aorta and the analysis of aging change--changes of elasticity of the aorta by aging].

For the purpose of the non-invasive measurement of the elastic properties of human abdominal aorta, we developed high sensitive measurement system of small displacement of tissue. This system consists of phase locked echo tracking loop combined with conventional B-mode imaging. The sensitivity to displacement in the model experiment was in the order of micro meter. Pressure strain elastic modulus (Ep) and stiffness parameter (beta) of abdominal aorta were calculated by our equipment in 61 persons, which were subdivided into 3 age groups, the young group (20 persons less than 35 yrs.), the middle aged group (21 persons between 35 yrs. and 60 yrs.), and the old group (20 persons more than 60 yrs.). Ep in the young group was 0.99 +/- 0.34 X 10(6) dynes/cm2, the middle aged group 1.55 +/- 0.68 X 10(6) dynes/cm2, the old group 3.80 +/- 2.05 X 10(6) dynes/cm2. Beta in the young group was 9.3 +/- 3.3, the middle aged group 12.0 +/- 4.5, the old group 27.6 +/- 14.0. The values of Ep and beta in the old group were significantly different from those in the young group and the middle group. Moreover large deviation of the both values was showed within the old group. The influence of aging on the elastic properties of abdominal aorta was found with large individual variation in relation to the progression of the sclerotic change.