Harmonic analysis of intravascular pressure response as an index of arterial wall mechanical properties.

The ability to routinely assess mechanical properties of large blood vessels, like the aorta, before an aneurysm or rupture occurs, could benefit diagnostic and therapeutic procedures and save lives. In this study, images of the wall area and intravascular pressure (IP) responses of in vitro rat aorta were recorded during swept frequency pressure input (2-200 Hz; +/- 10 mm Hg) superimposed on mean pressures from 20 to 160 mm Hg. Data analysis included Fast Fourier transform (FFT) of input and responses. Wall and IP responses were underdamped with respective resonance frequencies (Wn) that varied as a function of mean input pressure and the nonlinear nature of wall elasticity. Results indicated closely coupled wall and IP responses and suggested that the IP response may be an adequate index of wall elasticity without need of a direct measure of wall displacement. We considered results to be a key step towards development of a clinical tool which would facilitate analysis of mechanical properties of in vivo conducting vessels.