Color Doppler Tissue Imaging in Assessing the Elastic Properties of the Aorta and in Predicting Coronary Artery Disease

Abstract

We hypothesized that the change in aortic elastic properties could directly be shown with color Doppler tissue imaging (CDTI), that these findings could be related to aortic stiffness and distensibility and that, through these, coronary artery disease (CAD) could be predicted. One hundred and twenty six patients (group I: 83 with CAD, mean age 54+/-10 years, 18 female, 65 male; group II: 43 without CAD, mean age 53+/-10 years, 27 female, 16 male) having been evaluated for coronary artery disease by angiography were examined by echocardiography. Arterial pressure was measured immediately before echocardiographic evaluation. Internal aortic systolic and diastolic diameters by M-mode echocardiography and aortic upper wall tissue velocities (Aortic S, E, A, m/sec) by CDTI were measured 3 cm above the aortic valve. Lateral mitral annulus tissue velocities (Annulus S, E, A, m/sec) were also recorded. Aortic distensibility (cm2 x dynes(-1)) and aortic stiffness index were calculated using formulas. In the statistical analyses, CAD risk factors and left ventricular ejection fraction were used for adjustment. Aortic stiffness (2.79+/-3.49 vs 1.62+/-1.31, P=0.03), distensibility (1.55+/-1.46 vs 2.37+/-3.08, P=0.04), and aortic S velocity (0.057+/-0.016 vs 0.064+/-0.015, P=0.02) differed significantly between groups I and II. After adjustment, while aortic stiffness and S velocity were still statistically different (P=0.04; P=0.03 respectively), the significance of the difference in aortic distensibility disappeared (P=0.051). Aortic stiffness and aortic S velocity (0.06 m/sec<) were important CAD determinants (Odds ratio=1.4 P=0.03; Odds ratio=3.6 P=0.01, respectively), but aortic distensibility was not. Aortic stiffness was correlated only with aortic S velocity (r=-0.28, P=0.01), and aortic distensibility had a significantly positive correlation with aortic S velocity (r=0.20, P=0.02). The interobserver and intraobserver correlation coefficients for aortic S velocities were 0.65 and 0.71, respectively (P<0.05). Elastic properties of the aorta can directly be assessed by reproducibly measuring the movements in the upper wall of the aorta by CDTI. Reduced aortic S velocity is associated with increased aortic stiffness. Increased aortic stiffness and reduced aortic S velocity are important predictors of CAD.