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Fetal cardiac and peripheral arterial flow velocity waveforms in intrauterine growth retardation
I A Groenenberg1, J W Wladimiroff, W C Hop
1Department of Obstetrics & Gynecology, Erasmus University, Rotterdam, The Netherlands.
Insights
This study analyzed fetal blood flow in intrauterine growth retardation (IUGR) pregnancies. IUGR fetuses show altered flow velocities, indicating increased placental resistance and a "brain sparing" effect.
Area of Science:
- Fetal Medicine
- Cardiovascular Physiology
- Diagnostic Ultrasound
Background:
- Intrauterine growth retardation (IUGR) is associated with altered fetal circulation.
- Understanding fetal hemodynamic changes is crucial for managing IUGR.
Purpose of the Study:
- To investigate maximum flow velocity waveforms in cardiac and peripheral vessels in fetuses with IUGR.
- To assess fetal and placental vascular resistance in normal and IUGR pregnancies.
Main Methods:
- Doppler ultrasound was used to measure flow velocity waveforms in ascending aorta, pulmonary artery, ductus arteriosus, fetal internal carotid artery, descending aorta, umbilical artery, and maternal uteroplacental artery.
- 25 IUGR patients and 25 matched controls (gestational age 27-35 weeks) were studied.
- Analysis focused on peak systolic and end-diastolic velocities.
Main Results:
- Normal pregnancy showed low fetal and placental vascular resistances.
- IUGR fetuses exhibited reduced end-diastolic flow velocities in the descending aorta, umbilical artery, and uteroplacental artery, indicating increased resistance.
- Elevated end-diastolic velocities in the cerebral arteries suggested a "brain sparing" effect in IUGR.
Conclusions:
- Doppler velocimetry effectively identifies altered vascular resistance in IUGR.
- Reduced flow velocities in peripheral vessels and the "brain sparing" effect are key indicators of placental insufficiency in IUGR.
- Further research is needed to differentiate causes of reduced cardiac peak systolic flow velocities.
Abstract:
Maximum flow velocity waveforms were studied at the cardiac level (ascending aorta, pulmonary artery, and ductus arteriosus) and at the peripheral level (fetal internal carotid artery, descending aorta, umbilical artery, and maternal uteroplacental artery) in 25 patients with intrauterine growth retardation and 25 normal control subjects matched for gestational age and maternal parity. Gestational age ranged from 27 to 35 weeks (median, 30 weeks). All flow velocity waveforms were obtained with a mechanical sector scanner combined with a pulsed and continuous Doppler system with a carrier frequency of 3.5 and 3.0 MHz. Normal pregnancy was characterized by low fetal and placental vascular resistances. The peak systolic velocity in the ascending aorta was significantly higher compared with the pulmonary artery. In patients with intrauterine growth retardation, reduced end-diastolic flow velocities were documented in fetal descending aorta, umbilical artery, and maternal uteroplacental artery, reflecting raised umbilical placental and uteroplacental vascular resistances. Raised end-diastolic flow velocities were observed at the cerebral level, reflecting reduced cerebral vascular resistance ("brain sparing" effect). Reduced peak systolic flow velocities documented at the cardiac level may be secondary to reduced volume flow, increased valve or vessel size, or raised afterload. The noninvasive nature of this study did not allow differentiation between these variables.