Abstract 14569: Descriptive Analysis of the Evolution of Fetal Hemodynamics from 6 - 30 Weeks
Background: The complex hemodynamic changes that occur in the early developing human fetus remain ill-defined. We prospectively studied Doppler indices of fetal heart function in 124 consecutively encountered healthy pregnancies from 6-30 weeks of gestation.
Methods: 313 fetal echocardiograms performed on the 124 pregnancies were reviewed. All were <14 weeks gestational age (GA) at the first study. Doppler measures of fetal diastolic function, placental function, and systemic venous flows were obtained and data grouped by GA for analysis: first trimester (<10 weeks, 10-11+6, 12-13+6 weeks), early second trimester (14-17+6, 18-21+6 weeks), and ≥22 weeks. Statistical analysis was performed using one-way ANOVA for comparison of all means of continuous variables across groups and logistic regression for analysis of dichotomous variables across groups.
Results: Parameters of diastolic and global function, including atrioventricular valve (AVV) inflow durations and E/A wave ratios increased, and isovolumic relaxation time and Tei index decreased with advancing GA. At <10 weeks, AVV inflow duration corrected for heart rate was 0.26±0.06 sec, increasing to 0.45±0.04 sec by ≥22 weeks, with significant differences across age groups. Mean LV Tei index at <10weeks was 0.58±0.14, gradually decreasing to 0.33±0.09 at ≥ 22 weeks. Umbilical artery forward flow duration divided by R-R interval was 0.48±0.05 at <10 weeks and steadily increased to 1.00±0.07 at≥22 weeks . ANOVA revealed a significant difference between groups for all variables of diastolic function and placental resistance (p<0.0001). Umbilical venous pulsations were present in all at <10 weeks gestation and ductus venosus a wave reversal was present in 70% of early fetuses, steadily declining with GA and absent by 18 weeks. Inferior vena cava forward/reverse flow velocity time integral ratio increased from 7.7±6.1 at <10weeks to 10.9±3.8 at ≥22 weeks as a wave reversal gradually diminished (p=0.05).
Conclusion: Doppler observations in the very early fetus suggest the presence of reduced diastolic function which improves with gestation, and high placental relative to systemic vascular resistance which decreases with gestation. Both likely contribute to the trends in UV and systemic venous flow.
- © 2010 by American Heart Association, Inc.