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Published on: June 29, 2013
The relationship between Doppler indices from inferior vena cava and hepatic veins in normal human fetuses
Isoji Okura1, Yasunari Miyagi, Katsuhiko Tada
1Department of Obstetrics and Gynecology, Okayama University Graduate School of Medicine and Dentistry, Okayama 700-8558, Japan.
Insights
This study establishes gestational age-related reference ranges for fetal preload index in the inferior vena cava and hepatic veins. The preload index shows similar trends across these vessels throughout gestation.
Area of Science:
- Fetal echocardiography
- Cardiovascular physiology
- Perinatal medicine
Background:
- The preload index, calculated as peak atrial contraction velocity (A) over peak ventricular systole velocity (S), is a key hemodynamic parameter.
- Establishing gestational age-specific reference ranges for fetal venous preload is crucial for assessing cardiovascular health.
Purpose of the Study:
- To determine the gestational age-related reference range of the preload index (A/S) for the inferior vena cava (IVC) and hepatic veins.
- To compare the preload index regression lines among the IVC and three hepatic veins (right, middle, left).
Main Methods:
- Doppler measurements of 316 normal fetuses (22-40 weeks gestation).
- Calculation of the preload index (A/S) from recorded flow velocity waveforms.
- Statistical comparison of regression line slopes and intercepts using analysis of covariance.
Main Results:
- Preload index regression lines for all four veins decreased gradually throughout gestation.
- No significant differences were found in the slopes of the regression lines among the veins.
- Hepatic vein intercepts were significantly higher than the IVC intercept, but similar among hepatic veins.
Conclusions:
- The relationship between preload index and gestational age is statistically similar for the IVC and all studied hepatic veins.
- These findings support using a unified approach for assessing fetal venous preload across these vessels.
Abstract:
This study was conducted to determine the gestational age-related reference range of the preload index [peak velocity during atrial contraction (A)/peak velocity during ventricular systole (S)] for the inferior vena cava (IVC), the right hepatic vein, the middle hepatic vein and the left hepatic vein. The slope and the intercept of the regression line for each preload index were compared among the 4 veins using analysis of covariance. Doppler measurements were obtained for the 4 veins of 316 normal fetuses at 22-40 weeks of gestation. A and S values were measured from the recorded flow velocity waveform of each vein and the A/S ratio was calculated as the preload index. The regression lines for the preload index of the 4 veins decreased gradually throughout gestation. Analysis of covariance revealed no significant differences in the slopes of the regression lines for the 4 veins. However, the intercepts of the regression lines for all hepatic veins were significantly higher than that of the regression line for the IVC (P<0.0001), with the difference ranging from 0.024 to 0.033. There were no significant differences among the intercepts of the regression lines for different hepatic veins. We concluded that the relationship between the preload index and the duration of gestation was statistically similar for all hepatic veins, and strongly resembled that for the IVC.
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