COMPARISON OF THICKNESS AND DISTENSIBILITY IN THE CAROTID-ARTERY AND DESCENDING THORACIC AORTA - IN-VIVO ULTRASOUND ASSESSMENT

Early atherosclerotic changes in the carotid artery and thoracic aorta have been examined by high-frequency ultrasound measuring of intimal- medial thickness and stiffness. Whether changes in stiffness and thick ness occur in parallel and whether the determinants of stiffness and t hickness in the two vessels are similar is unknown. To examine the rel ation between ultrasonographic measures of atherosclerosis in the caro tid and the thoracic aorta, 146 patients aged 20 to 84 years (mean 54 years) were studied by both transesophageal echocardiography (TEE) and carotid duplex scanning. From two-dimensionally derived M-mode record ings of the thoracic aorta and high-frequency B-mode imaging of the co mmon carotid, the intimal-medial thickness was measured along with dia stolic and systolic diameters for calculation of stiff ness. Interobse rver and intraobserver variability of carotid and aortic intimal-media l thickness and diameter were low. There was a good relation between c arotid and aortic intimal-medial thickness (r = 0.69; p = 0.0001). Age was the major independent determinant of thickness in both vessels. C arotid and aortic stiffness, as measured by Peterson's elastic modulus , were less closely related (r = 0.51; p = 0.0001). Age was the only i ndependent predictor of stiffness in both vessels. In conclusion, stru ctural ultrasonographic manifestations of early atherosclerosis in the carotid artery and thoracic aorta are closely related. Large populati on studies measuring only carotid intimal-medial thickness may reflect atherosclerotic changes occurring throughout the vascular bed.