TRANSESOPHAGEAL ECHOCARDIOGRAPHIC ASSESSMENT OF THE EFFECTS OF AGE, GENDER, AND HYPERTENSION ON THORACIC AORTIC-WALL SIZE, THICKNESS, AND STIFFNESS

Aging is associated with progressive arterial stiffening and widening of the pulse pressure, resulting in a high prevalence of systolic hypertension. The contribution of increased aortic thickness to this process and to essential hypertension has been poorly characterized. With transesophageal echocardiography, aortic thickness and diameter can be measured. Thus, the influence of aging, gender, and hypertension on the geometry and stiffness of the descending thoracic aorta in humans can be determined in vivo. In 83 patients undergoing transesophageal echocardiography for clinical indications, recordings of the descending thoracic aorta were made. There were 53 normotensive subjects (33 men and 20 women, mean age 46 years, range 14 to 79 years) and 25 hypertensive subjects (8 men and 17 women, mean age 67 years, range 50 to 80 years). Measurements of diastolic and systolic aortic thickness and aortic diameter were made, and three measures of the elastic properties of the aorta were calculated: (1) Peterson's elastic modulus, (2) Young's modulus, and (3) the stiffness index beta. Aortic thickness averaged 1.1 +/- 0.1 mm in both normotensive men and women. Normotensive women had a significantly greater thickness/diameter ratio than men (0.06 +/- 0.01 vs 0.05 +/- 0.01, p < 0.01), but there were no differences in stiffness between men and women. Age was highly positively correlated with thickness (r = 0.74, p < 0.001), diameter (r = 0.67, p < 0.001), beta (r = 0.79, p < 0.001), Peterson's modulus (r = 0.78, p < 0.001), and Young's modulus (r = 0.81, p < 0.001). In comparison to the 20 normotensive subjects >50 years old with a similar mean age, the hypertensive subjects had significantly increased wall thickness (0.14 +/- 0.02 vs 0.12 +/- 0.01 mm, p < 0.00004) and beta. In conclusion, aging significantly increases aortic thickness and stiffness. Women have significantly higher relative aortic wall thickness than men but a similar stiffness. Hypertension increases aortic thickness and stiffness. These data further characterize the aortic geometry and its relation to the compliance properties of the vessel and suggest fundamental structural elements contributing to the vascular effects of aging and systemic hypertension.