P8.14 ELASTIC MODULUS OF HUMAN AORTAS AS A MEASURE OF STIFFNESS

Abstract

Background: Although arterial stiffness is of clinical interest, data on the elastic modulus of the human aortic wall are scarce. The aim of this work is to directly measure the elastic modulus of human aorta ex vivo. Methods: Using a standard tensiometer, we measured the elastic modulus (E) of human aortic rings (n=205). Wall thickness and diameter were measured, and the pulse wave velocity (PWV) for each aorta was calculated using Moens-Kortweg equations. The results were analysed based on age, gender and aortic site, then compared with data obtained in living subjects using MRI (n=160). Results: At 100mmHg pressure, E of aortic rings increased with age, with a commiserate increase in PWV: under 30 years = 3.73±0.49; 30–39 years = 3.32±0.58; 40–49 years = 3.32±0.49; 50–59 years = 3.55±1.00; 60–69 years = 4.05±1.21; 70–79 years = 4.52±1.26; 80–89 years=5.59±0.39 m/s. There was no significant difference in either E or PWV between genders. There was also no significant difference in E or PWV based on aortic site, likely due to under-representation of most sites. PWV measured in vivo using MRI was higher every age: under 30 years = 3.96±0.51; 30–39 years = 4.47±0.61; 40–49 years = 4.85±0.75; 50–59 years = 5.97±1.14; 60–69 years = 6.64±1,16; 70–79 years = 9.40±4.24 m/s. The difference between in vivo and ex vivo measurements increased with age. Conclusions: PWV calculated from ex vivo E measurements reflect established physiological patterns, suggesting that direct elastic modulus measurement may be an acceptable method for analysing stiffness in aortic tissue.