Abstract 14743: Reference Values of Right Atrial Function Parameters in the Fetus Using Velocity Vector Imaging
Background: In the fetal circulation, blood from systemic and umbilical vein flows through the right atrium (RA) and is distributed to the right ventricle or via the foramen ovale, to the left ventricle. RA function, therefore, is important in determining both left and right ventricular preload. We have recently documented abnormal RA function in fetal Ebstein anomaly which likely contributes to the hemodynamic compromise observed in affected fetuses. Data on normal fetal RA function is limited. Using velocity vector imaging (VVI), we determined normal values of RA function parameters in the fetus.
Methods: Thirty-three normal fetuses were prospectively studied. We reported the mean of three offline measurement of RA emptying fraction (EF), RA filling and emptying rates, RA maximum (Volmax) and minimum (Volmin) volumes and RA fractional area change (FAC), performed using a stored four-chamber 2D image analyzed with VVI software (Siemens). Additionally RA filling and emptying rates were normalized to Volmax and Volmin respectively. Interobserver variability was performed on 15 fetuses. Interobserver intraclass correlation coefficient was calculated for reproducibility testing.
Results: The median fetal gestation was 26 weeks (range 18-35 weeks). Gestation age-dependent RA parameters include Volmax (r=0.92), Volmin (r=0.88), filling (r=0.90) and emptying rate (r=0.92). In contrast EF (r=0.16), FAC (r=0.18), normalized filling rate (r=0.16) and emptying rate (r=0.18) were independent of gestational age. Normal values of gestation age-independent mean RA functional parameters included: EF 52% ± 9, FAC 43% ± 7, normalized filling rate 3.2ml/s ± 0.7 and normalized emptying rate -9.7ml/s ± 3.3. Interobserver intraclass correlation coefficient for EF (r=0.91), FAC (r=0.85), filling rate (r=0.96), emptying rate (r=0.91), Volmax (r=0.93) and Volmin (r=0.93) were high.
Conclusion: VVI provides reproducible and useful reference data for RA function. RA EF and FAC are gestation age-independent through the second and third trimesters in normal fetuses. Although absolute rates of RA filling and emptying increase with gestational age, when corrected for RA volume these parameters are also gestational age-independent.
- © 2010 by American Heart Association, Inc.