Aortic flow is associated with aging and exercise capacity

Abstract

Aims Increased blood flow eccentricity in the aorta has been associated with aortic (AO) pathology, however, its association with exercise capacity has not been investigated. This study aimed to assess the relationships between flow eccentricity parameters derived from 2-dimensional (2D) phase-contrast (PC) cardiovascular magnetic resonance (CMR) imaging and aging and cardiopulmonary exercise test (CPET) in a cohort of healthy subjects. Methods and Results One hundred and sixty-nine healthy subjects (age 44 ± 13 years, M/F: 96/73) free of cardiovascular disease were recruited in a prospective study (NCT03217240) and underwent CMR, including 2D PC at an orthogonal plane just above the sinotubular junction, and CPET (cycle ergometer) within one week. The following AO flow parameters were derived: AO forward and backward flow indexed to body surface area (FFi, BFi), average flow displacement during systole (FDsavg), late systole (FDlsavg), diastole (FDdavg), systolic retrograde flow (SRF), systolic flow reversal ratio (sFRR), and pulse wave velocity (PWV). Exercise capacity was assessed by peak oxygen uptake (PVO2) from CPET. The mean values of FDsavg, FDlsavg, FDdavg, SRF, sFRR, and PWV were 17 ± 6%, 19 ± 8%, 29 ± 7%, 4.4 ± 4.2 mL, 5.9 ± 5.1%, and 4.3 ± 1.6 m/s, respectively. They all increased with age (r = 0.623, 0.628, 0.353, 0.590, 0.649, 0.598, all P < 0.0001), and decreased with PVO2 (r = −0.302, −0.270, −0.253, −0.149, −0.219, −0.161, all P < 0.05). A stepwise multivariable linear regression analysis using left ventricular ejection fraction (LVEF), FFi, and FDsavg showed an area under the curve of 0.769 in differentiating healthy subjects with high-risk exercise capacity (PVO2 ≤ 14 mL/kg/min). Conclusion AO flow haemodynamics change with aging and predict exercise capacity. Registration NCT03217240

Cardiac MR modelling of systolic and diastolic blood pressure

“…For flow analysis, we used semiautomated segmentation methods of the ascending and descending aorta throughout the cardiac cycle previously described by our group. 20 Aortic forward and backward flows were acquired from the resultant flow curve ( figure 2 ). The peak systolic phase was defined as the peak flow rate on the flow curve ( figure 2 ).…”

“…The CMR protocol included baseline survey images and cines and gadolinium enhancement imaging acquisition methods previously described by our group. [14][15][16][17][18][19][20] For standard cines, we acquired 30 phases throughout the cardiac cycle. Other cine acquisition parameters include TR: 2.71, TE: 1.13, field of view (FOV): 360 × 289.3 mm 2 with phase FOV-80.4%, number of signal averages: 1, matrix: 224×180 (phase), bandwidth: 167.4 kHz, (930 Hz/Px), flip angle: 80, slice thickness: 8 mm and Grappa acceleration with a factor of 2.…”