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Updated: Mar 21, 2026
Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction
Published on: June 29, 2013
Impact of pulsed Doppler sample volume position on fetal cardiac output calculation
Kosuke Yonehara1, Kiyohiro Takigiku2, Noboru Tanaka3
1Department of Pediatric Cardiology, Nagano Children's Hospital, Azumino, Nagano, 399-8288, Japan. kosuke-yonehara@nkodomo-hsp.jp.
Insights
Fetal cardiac output (CO) measurements are significantly affected by sample volume position. Measuring the velocity time integral (VTI) at the valve hinge level provides more accurate fetal CO assessments.
Area of Science:
- Cardiology
- Fetal Medicine
- Medical Imaging
Background:
- Accurate fetal cardiac output (CO) assessment is crucial for monitoring fetal well-being.
- The pulsed Doppler method is commonly used for CO measurements, but its accuracy can be influenced by technical factors.
- Understanding the impact of sample volume placement is essential for reliable fetal CO evaluation.
Purpose of the Study:
- To evaluate how the position of the sample volume affects fetal cardiac output (CO) measurements.
- To compare CO measurements obtained at the valve hinge level versus just distal to the valve.
- To assess the correlation of pulsed Doppler-derived CO with three-dimensional echocardiography.
Main Methods:
- Fetal cardiac output (CO) was measured in fetuses with normal hearts using pulsed Doppler.
- Velocity time integral (VTI) was recorded at the valve hinge (V group) and supra-valve (S group) positions.
- Three-dimensional electronic spatio-temporal image correlation (eSTIC) data were acquired for volume analysis.
- Left-ventricular CO was calculated using stroke volume (derived from VOCAL technique) and heart rate.
Main Results:
- The supra-valve (S) group showed significantly larger aortic and pulmonary valve VTI compared to the valve hinge (V) group.
- Combined cardiac output (CCO) was significantly higher in the S group (450 mL/kg/min) than in the V group (396 mL/kg/min).
- Left-ventricular CO measurements in the V group (140 mL/kg/min) were more similar to those obtained using eSTIC (133 mL/kg/min) than the S group (157 mL/kg/min).
Conclusions:
- Fetal cardiac output (CO) measurements are significantly influenced by the sample volume position.
- Measuring the velocity time integral (VTI) at the valve hinge level provides a more accurate reflection of fetal CO.
- Optimizing sample volume placement is critical for precise fetal hemodynamic assessment.
Purpose:
This study aimed to evaluate the impact of sample volume position on fetal cardiac output (CO) measurements.
Methods:
Fetuses with normal hearts were enrolled. Fetal CO was calculated using the pulsed Doppler method, with the velocity time integral (VTI) recorded at two distinct positions: the valve hinge level (Valve: V group) and just distal to the valve (Supra-valve: S group). Additionally, we acquired electronic spatio-temporal image correlation (eSTIC) volume data. Left-ventricular CO was calculated as the product of stroke volume and heart rate, with stroke volume derived from left-ventricular volume measurements using the virtual organ computer-aided analysis (VOCAL) technique on the three-dimensional eSTIC data (eSTIC group). We then compared the left-ventricular CO levels among the V, S, and eSTIC groups to assess their correlation.
Results:
The S group showed significantly larger VTI of the aortic valve (8.5 ± 2.3 vs. 9.3 ± 2.5 cm, V vs. S group). Similarly, the S group also had significantly larger VTI of the pulmonary valve (7.0 ± 1.9 vs. 8.2 ± 2.2 cm). Combined cardiac output (CCO) in the V group was 396 ± 136 mL/min/kg, and that in the S group was 450 ± 154 mL/kg/min, which also showed that the S group had a significantly larger CCO. Focusing on left ventricle CO, the V group was 140 ± 73 mL/kg/min, the S group was 157 ± 77 mL/kg/min, and the eSTIC group was 133 ± 69 mL/kg/min. This suggested that the V group's results were more similar to the eSTIC group's.
Conclusion:
This study suggests that CO measurements are significantly influenced by the sample volume position. Furthermore, placing the VTI sample volume on the valve hinge level appears to reflect CO more accurately.
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