153 Normal values of aortic elasticity in 58 adults using Cine-MRI

Abstract

Currently, the recommendation for prophylactic intervention of aortic replacement is based on aortic diameters. Clinical trials have shown that this parameter is not always reliable. Aortic elasticity is a crucial parameter in the follow up of patients at risk. Compliance and distensibility measures can distinguish patients at risk for rupture or dissection from healthy adults, although no norm exists. The purpose of this study was to determine normal values of compliance/distensibility of the thoracic aorta in healthy adults using cine-MRI. The influence of sex and tobacco was evaluated. 58 adults (mean age 34.8 ± 11 years), with no history of cardiovascular disease were recruited. Cine-MRI was performed at the level of the pulmonary trunk. Aortic compliance is defined as the relative change in aortic cross-sectional area divided by the change in arterial pressure. Distensibility is calculated as compliance reported to minimal surface area. Automatic post-processing was used to analysis surface areas. Results show that sex and tobacco have no influence on compliance and distensibility, confirming their small impact on thoracic aortic aneurisms and dissections. Compliance and distensibility values from the ascending aorta correlated negatively with age (r=0,68; p<0.0001 and r=0,77; p<0.0001). Age relative to body surface area is the main factor in aortic stiffness variations in healthy subjects. Prediction curves characterizing normal compliance and distensibility values for a given age are created with confidence interval of 95%.This study on a healthy subject population provides reference values for aortic stiffness. In the management of patients, compliance and distensibility parameters should support surgical indication for patients.