Aortic backward flow indices estimated from phase-contrast cardiovascular magnetic resonance data

Aging is a major cardiovascular risk factor and is associated with arterial stiffness. We hypothesized that quantitative parameters related to backward flow (BF) in the ascending aorta (AA) estimated from phase-contrast cardiovascular magnetic resonance (PC-CMR) data could be relevant markers of aging. We studied 100 healthy subjects (age: 40±15years). Aortic stiffness (aortic arch pulse wave velocity, AA distensibility) and geometry (AA diastolic diameter and arch length) indices and parameters of AA global flow, forward flow (FF) and BF (volumes and flow rate peaks) were semi-automatically estimated from 2D PC-CMR data. Carotid-femoral pulse wave velocity and carotid augmentation index (AIx) were assessed using applanation tonometry. AA flow parameters were highly reproducible (interobserver variability<;1.6±8.4%). Aortic BF significantly increased in terms of volume and flow rate peak with age (r>;0.50, p<;0.0001), while global flow and FF parameters were stable (p>;0.06). Multivariate analysis showed that BF was strongly associated to aortic geometry and AIx independent of age, gender, body size, blood pressure and heart rate. Thus, aortic PC-CMR BF parameters could be early functional markers of subclinical impairment of circulatory efficiency and could help to further understand physiology of vascular aging.