No abstract

1. Non-invasive aortic compliance measurements have been used previously to assess the distensibility of the aorta in several pathological conditions associated with increased cardiovascular risk. In adult patients with familial hypercholesterolaemia and those with growth hormone deficiency, aortic compliance has been found to correlate inversely with plasma cholesterol levels and age. We set out to establish if a relationship existed between the biophysical measurement of aortic compliance and biochemical variables in normal healthy adult subjects. 2. Blood pressure-corrected aortic distensibility, fasting insulin, insulin-like growth factor-I, total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol and triacylglycerol were measured in 38 (18 males, 20 females) normotensive healthy adults. 3. Blood pressure-corrected aortic distensibility was found to correlate inversely with age (r = -0.67, P < 0.001), low-density lipoprotein-cholesterol (r = -0.37, P < 0.02) and the low-density lipoprotein-/high density lipoprotein-cholesterol ratio (r = -0.33, P < 0.05) and positively with insulin-like growth factor-I (r = 0.47, P < 0.01). On separate analysis by sex, significant inverse correlations were observed in females between aortic distensibility and total cholesterol (r = -0.50, P < 0.02), low-density lipoprotein-cholesterol (r = -0.55, P < 0.01) and age (r = -0.74, P < 0.001). A positive correlation was found between aortic distensibility and insulin-like growth factor-I (r = 0.48, P < 0.05). On forced stepwise regression analysis, however, only age (P < 0.02) was found to be significant. In males, an inverse correlation was found between aortic distensibility and age (r = -0.57, P < 0.01), low-density lipoprotein-cholesterol (r = -0.51, P < 0.05), and the low-density lipoprotein-/high-density lipoprotein-cholesterol ratio (r = -0.63, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Both oestrogen and androgens have been shown to affect the structural composition and biophysical properties of the arterial wall in vitro. A non-invasive Doppler ultrasound technique, based on the measurement of pulse wave velocity along the thoraco-abdominal aortic pathway, was used to assess aortic compliance C in vivo in 49 normotensive, normal, healthy post-menopausal female subjects. 23 of the women had been receiving Tibolone, a synthetic steroid structurally related to norethisterone, for at least 3 years. Since C varies with non-chronic changes in blood pressure, an index of intrinsic aortic distensibility, Cp, normally independent of blood pressure, was also calculated. No significant difference was found between the control group and those subjects receiving Tibolone for age, body mass index, systolic blood pressure, diastolic blood pressure, C or Cp. As one would expect the control group Cp values did not show a significant relationship with blood pressure (r = -0.1, not significant). However, in the Tibolone group some dependence of Cp values on pressure still remained (r = -0.58, p < 0.004), suggesting that oral administration of Tibolone had altered the dynamic relationship between structural and functional biophysical properties of the aortic wall in vivo.