Normal values for mitral and tricuspid early inflow blood flow velocity variation using real time phase contrast cardiovascular magnetic resonance

Ventricular interdependence occurs when pressure changes in one cardiac chamber affect the other, which can be exaggerated in cardiac pathology. The aim of this study was to develop a more automated, clinically accessible and freely available method to measure ventricular interdependence as respiratory variation in mitral and tricuspid peak early velocities. Patients without pericardial effusion or thickening (n=26, median age 55 years, 31% female), one patient with constrictive pericarditis, one patient with 35 mm pericardial effusion and healthy volunteers (n=13, median age 52 years, 76% female) underwent real-time phase-contrast cardiovascular magnetic resonance (CMR) at 3T in a basal short-axis view during free breathing. Healthy volunteers were imaged twice. Respiratory variation in mitral and tricuspid peak early inflow velocities was calculated as (Vmax-Vmin)/Vmax. In patients without pathology and healthy volunteers, which were pooled (n=39), respiratory variation was 23{+/-}6% (upper normal limit 34%) for mitral velocities and 40{+/-}10% (upper normal limit 60%) for tricuspid velocities. Patients with pathology exhibited increased respiratory variation. Test-retest variability and inter-observer agreements were excellent. The proposed method for quantifying respiratory variation of mitral and tricuspid inflow velocities by CMR is feasible, reproducible and normal values are presented.