Validating aortic stiffness parameters by cardiac magnetic resonance against mechanical testing of ex-vivo aortic aneurysms specimens

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main source(s): Instituto de Salud Carlos III, Sociedad Española Cardiología Background Aortic stiffness is a predictor incident cardiovascular events and mortality in the general population (1). Cardiovascular magnetic resonance (CMR) imaging allow to compute number parameters, such as pulse wave velocity (PWV), distensibility (AD) aortic longitudinal strain, theoretically related wall stiffness, but no formal validation has ever been reported. Purpose To test correlation between PWV, AD strain assessed via ex-vivo mechanical testing specimens. Methods Patients undergoing ascending aorta (AAo) aneurysms resection underwent CMR study which included bSSFP images 4D flow thoracic aorta. At surgery 2 AAo specimens (each 15x5 mm, one oriented other circumferential direction) were extracted, maintaining record their in-vivo position orientation, frozen. Specimens tested under control for extension force (I5558, INSTRON) elongation was quantifies by laser video extensometer (2663–281, INSTRON). The Young's modulus (E), i.e. tangent stress-strain curve, quantified at patient’s diastolic pressure during (2). PWV extracted from product Eh (h being thickness) computed Moens-Korteweg equation using mean diameter(3,4). cine pulmonary artery level ARTFUN software (INSERM U678, France) while deformation tracking root cardiac cycle (5). Results Twenty patients included: age 52.5 [37.3 71.0] years, 13 (65%) male, BSA 1.94 [1.74 1.94] m2. Most had degenerative origin tricuspid valve, bicuspid 9 connective tissue disorders. Due missing data, two could not have specimen direction patient be tested. strongly associated with elastic blood (R = 0.652, R 0.602 -0.502, respectively) (Figure 1). Strong association also obtained -0.513). Conclusion Pulse derived product, non-invasively are reliable representation stiffness.