Noninvasive assessment of the viscoelasticity of peripheral arteries

Currently used methods of examining the mechanical properties of blood vess el walls are either indirect or invasive, or measure vessel diameter and pr essure waveforms at different sites, We developed a noninvasive technique t o assess the mechanical properties and viscoelasticity of peripheral arteri es. The pressure-strain elastic modulus (Ep) and the viscoelastic propertie s (energy dissipation ratio, EDR) of the common carotid artery (CCA), brach ial artery (BA), radial artery (RA) and dorsalis pedis artery (DPA) were de termined by means of palpating pressure and diameter distension waveforms e xtracted from high-resolution ultrasonography, The methodology was validate d in vitro using an elastic tube phantom, as well as in vivo, In vivo study in 10 healthy volunteers (mean age 22 y) showed that the pressure-diameter curves were nonlinear, with an inflection at about 85-90 mmHg, and routed clockwise with slight hysteresis. The CCA (n = 5) had a mean diameter of 6. 74 mm and the pulsatile diameter distension was 12.2%, The Ep calculated at the CCA was 0.44 x 10(6) dyne/cm(2) with an EDR of 7.18%, The BA, RA and D PA (n = 10) had mean diameters of 3.91 mm, 2.21 mm and 2.12 mm; arterial st rains of 4.60%, 4.25% and 8.91%; mean Ep of 1.39, 1.45, 0.90 x 10(6) dyne/c m(2); and mean EDRs of 6.34%, 6.15% and 5.60%, respectively. The method pre sented is relatively simple to implement clinically and has potential as a new diagnostic tool for detecting local vascular changes. (C) 1999 World Fe deration for Ultrasound in Medicine & Biology.