Noninvasive assessment of Doppler-derived estimated fetal interatrial pressure-gradient indices using ductus venosus and pulmonary vein velocities in late-onset fetal growth restriction: a prospective case-control study.

Doppler-derived interatrial pressure-gradient indices show no significant differences in FGR unless severe compromise is present. Pulmonary vein D-wave velocity is reduced in FGR, indicating potential diastolic dysfunction.

Summary and findings

This study measured Doppler-derived estimated fetal interatrial pressure-gradient indices in 40 late-onset FGR fetuses and 40 controls. No significant differences were found between groups, except for reduced pulmonary vein D-wave velocity in FGR fetuses. Subgroup analysis showed lower gradient indices in FGR fetuses with high umbilical artery pulsatility index.

Abstract

<h4>Background</h4>Fetal growth restriction (FGR) is associated with progressive hemodynamic deterioration and subclinical cardiac dysfunction. The modified Bernoulli equation applied to ductus venosus and pulmonary vein Doppler velocities allows noninvasive estimation of fetal interatrial pressure gradients; however, the utility of this approach in FGR has not been empirically evaluated.<h4>Methods</h4>This prospective case-control study, conducted at a single tertiary referral center, enrolled 40 late-onset FGR fetuses meeting Delphi consensus criteria and 40 gestational age-matched controls. Doppler-derived estimated interatrial pressure-gradient indices were calculated noninvasively by applying the modified Bernoulli equation to ductus venosus and pulmonary vein Doppler peak velocities obtained sequentially during the same examination session. In addition, standard arterial and venous fetal Doppler indices were recorded. Group comparisons were performed using the Mann-Whitney U test, with effect sizes quantified by Cliff's delta.<h4>Results</h4>No significant difference was observed in any of the three estimated interatrial pressure gradient indices between FGR and control fetuses (<i>p</i> = 0.447, <i>p</i> = 0.665, and <i>p</i> = 0.729, respectively). Pulmonary vein D-wave velocity was significantly reduced in FGR fetuses (18.20 [IQR 13.43-22.40] vs. 20.90 [IQR 15.97-25.60] cm/s; <i>p</i> = 0.021), whereas ductus venosus velocity parameters did not differ between groups. In a subgroup analysis of eight FGR fetuses with umbilical artery pulsatility index at or above the 95th centile, all three gradient indices were significantly lower than in controls (<i>p</i> ≤ 0.010), with large effect sizes (Cliff's δ 0.581 to 0.762).<h4>Conclusions</h4>Doppler-derived estimated interatrial pressure-gradient indices do not differ significantly between FGR and control fetuses in the absence of ductus venosus a-wave abnormalities. In an exploratory subgroup analysis, significantly lower gradient indices were observed in fetuses with UA PI at or above the 95th centile; this finding should be considered hypothesis-generating. Furthermore, pulmonary vein D-wave velocity was significantly reduced in FGR fetuses, a finding that may reflect altered left ventricular diastolic filling dynamics; however, definitive conclusions regarding diastolic dysfunction require dedicated cardiac function assessment. Collectively, these findings provide the first characterization of Doppler-derived estimated interatrial pressure-gradient indices in late-onset FGR and suggest that interatrial hemodynamic alterations emerge only at more advanced stages of fetoplacental compromise.

Key findings

• No significant difference in interatrial pressure gradient indices (p=0.447, p=0.665, p=0.729).
• Pulmonary vein D-wave velocity reduced in FGR (18.20 cm/s vs 20.90 cm/s, p=0.021).
• Subgroup with high UA PI showed lower gradient indices (p≤0.010, Cliff's δ 0.581 to 0.762).

Limitations

• Single-center study
• Small sample size (n=80)
• Exploratory subgroup analysis
• No dedicated cardiac function assessment

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