[The effect of aging and sclerosis on the viscoelastic properties of the human thoracic aorta].

This paper describes some results of our research on the viscoelastic properties of the human aorta. Pressure-diameter relations of 45 thoracic aortas, aged 30 to 88 years, were measured. The complex static measurement results were described by a model (formula) with three parameters. The dynamic (viscous) measurement results needed four parameters in a different model. De model parameters were next related to the age and the degree of sclerosis of the aortic segments. The results can be summarized as follows: the static properties change strongly with age; aortic compliance decreases substantially with aging; the dynamic (viscous) properties of the aorta do not change with age; although the degree of sclerosis of the aorta increased with age, we could not demonstrate a significant difference in the viscoelastic properties of 'normal' and sclerotic aortas. An explanation for the latter phenomenon was found in the dilation of the aorta which accompanies the increase of the degree of sclerosis and which serves as a hemodynamic compensation.