Evaluation of arterial wall histological and physical characteristics using intravascular echography

Using a high-frequency ultrasound intravascular imaging system we evaluated the intravascular echo image by comparing it with histological findings in 57 arterial segments of 17 autopsy cases. Moreover, in 8 dogs we estimated the arterial elastic property by observing the change of the arterial section accompanying a reduction of arterial pressure due to hemorrhage (H) or nifedipine infusion (N). The characteristics of the intravascular echograms were as follows: 1) In a normal artery the arterial wall consisted of the inner high echoic, the medial low echoic and the outer high echoic layers. 2) In an aged artery the fibrous thickened intima was seen as the low echo layer giving an echo about the same as that of the normal media, and the intensity of the echo from the degenerated media was lower than that of the normal media. 3) In atheroma the echo intensity of the elastic fiber-rich region was higher than that of the surrounding region, while the calcified region showed as a brighter echo with outer echo free space due to shadowing. We measured the arterial radius, area and circumferential length on the intravascular echo image and calculated the arterial wall tension-circumferential length and the pressure-arterial area relationships. By analysing each relation, we obtained the stiffness and compliance parameters, respectively. The stiffness parameter with N was lower than that with H [(1.5 +/- 0.5) x 10(-2) vs (2.8 +/- 0.9) x 10(-2)] and the compliance parameter with N was higher than that with H (0.92 +/- 0.28 vs. 0.46 +/- 0.12).(ABSTRACT TRUNCATED AT 250 WORDS)