Aortic compliance measurements using Doppler ultrasound: in vivo biochemical correlates

A noninvasive Doppler ultrasound technique for the assessment of aortic compliance based on the in vivo measurement of pulse wave velocity along the thoraco-abdominal aortic pathway is described. An approach for correcting for the effect of blood pressure on aortic distensibility is considered. The derivation of an index of intrinsic distensibility, Cp, which is independent of blood pressure, is provided and applied to data collected from normal, healthy volunteers. Overviews are provided of studies utilising the technique to determine aortic compliance in medical disorders, which are known to predispose to premature cardiovascular disease, such as diabetes mellitus, familial hypercholesterolaemia and growth hormone deficiency. The significance of correlations between in vivo aortic compliance measurements and plasma concentrations of total cholesterol, low-density-lipoprotein cholesterol, high-density-lipoprotein cholesterol and insulin-like growth factor-I are discussed. It is proposed that the measurement of aortic compliance in normal, healthy individuals may potentially be a useful in vivo research tool for investigating the effects of biochemical factors on the biophysical properties of the aortic wall. Furthermore, we believe that the routine measurement of blood pressure-corrected aortic distensibility may prove a useful, noninvasive clinical tool for assessing patients' susceptibility to atherosclerosis, as well as for monitoring their response to therapeutic interventions.