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Updated: Jul 6, 2026
Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation
Published on: January 7, 2021
Color M-mode propagation velocity, but not its ratio to early diastolic inflow velocity, changes throughout gestation
A J Moon-Grady1, D Taylor, S H Bennett
1Department of Pediatrics, University of California Davis, Sacramento, San Francisco, CA, USA. anita.moongrady@ucdmc.ucdavis.edu
Insights
Fetal diastolic function, measured by propagation velocity (Vp), is lower than in adults. Vp in fetal right ventricles improves with gestation, indicating developing diastolic function, but interobserver variability poses challenges for clinical use.
Area of Science:
- Cardiology
- Fetal Medicine
- Diagnostic Ultrasound
Background:
- Diastolic function is crucial for cardiac health and is assessed using propagation velocity (Vp) in adults.
- Early detection of diastolic compromise in fetuses may prevent heart failure.
- Understanding fetal diastolic function aids in managing high-risk pregnancies.
Purpose of the Study:
- To establish normal values for Vp and early diastolic inflow velocity (E) in fetuses.
- To analyze how these measurements change with gestational age.
- To assess the reliability of Vp measurements through interobserver and intraobserver variability analysis.
Main Methods:
- Echocardiography was performed on 32 normal fetuses (20-35 weeks gestation).
- Color M-mode Vp was measured in both right (RV) and left (LV) ventricles.
- Pulsed-wave Doppler assessed mitral and tricuspid inflow velocities (E); values were compared to adult data.
Main Results:
- Fetal Vp values (RV: 15.3 cm/s, LV: 20.8 cm/s) were lower than adult values, with RV Vp significantly lower than LV Vp.
- Gestational age showed a linear correlation with RV Vp (R=0.69).
- Interobserver bias was high (19%), while intraobserver bias was low (1.1%).
Conclusions:
- Fetal Vp is lower than adult Vp, with RV Vp indicating improved diastolic function during gestation.
- Vp measurements are feasible for assessing fetal diastolic function.
- High interobserver variability requires further investigation for reliable clinical application.
Objectives:
Color M-mode propagation velocity (Vp) is a measure of diastolic function in adults and, when combined with early diastolic inflow velocity (E), the ratio E/Vp reflects ventricular filling pressure. Early detection of diastolic compromise may benefit fetal patients at risk for developing heart failure. The objectives of this study were to measure values for Vp and inflow peak E in a group of normal fetuses, to analyze age-dependent alterations in these measurements, and to evaluate the interobserver and intraobserver variability of the measurements.
Methods:
Thirty-two normal fetuses at between 20 and 35 weeks' gestation underwent echocardiography. Color M-mode Vp was measured from the four-chamber view for the right (RV) and left (LV) ventricles, and mitral and tricuspid inflow velocities were determined by pulsed-wave Doppler ultrasound. The values obtained were compared with previously reported findings in adults.
Results:
Adequate tracings were obtainable in 23 patients for the RV and 29 for the LV. Mean Vp values for the RV (15.3 +/- 3.2 cm/s) and LV (20.8 +/- 5.6 cm/s) were lower than normal adult values, and Vp values were significantly lower for the RV than the LV (P < 0.001). Applying Bazett's heart rate correction, values for RV (23.4 +/- 4.8 cm/s) and LV (31.9 +/- 8.7 cm/s) remained lower than normal adult values. There was a linear correlation of Vp with gestational age for the RV (R = 0.69, P < 0.001), and the ratio of E/Vp corrected for heart rate for the RV (1.51 +/- 0.26) remained constant throughout gestation. Interobserver bias was high but intraobserver bias low, at 19 and 1.1%, respectively.
Conclusions:
Vp is lower in fetal than in adult life. Vp for the RV changes in a manner indicative of improving diastolic function throughout normal gestation, providing insight into the alterations in diastolic function with gestation that contribute to increases in cardiac output. The use of Vp to assess diastolic function disturbance in fetuses is feasible, but high interobserver variability is problematic.
