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 thickness occur in parallel and whether the determinants of stiffness and thickness in the two vessels are similar is unknown. To examine the relation between ultrasonographic measures of atherosclerosis in the carotid 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 recordings of the thoracic aorta and high-frequency B-mode imaging of the common carotid, the intimal-medial thickness was measured along with diastolic and systolic diameters for calculation of stiffness. Interobserver and intraobserver variability of carotid and aortic intimal-medial thickness and diameter were low. There was a good relation between carotid and aortic intimal-medial thickness ( r = 0.69; p = 0.0001). Age was the major independent determinant of thickness in both vessels. Carotid and aortic stiffness, as measured by Peterson's elastic modulus, were less closely related ( r = 0.51; p = 0.0001). Age was the only independent predictor of stiffness in both vessels. In conclusion, structural ultrasonographic manifestations of early atherosclerosis in the carotid artery and thoracic aorta are closely related. Large population studies measuring only carotid intimal-medial thickness may reflect atherosclerotic changes occurring throughout the vascular bed.