Jacqueline A. M. Laudy

Doppler Velocimetry in Branch Pulmonary Arteries of Normal Human Fetuses during the Second Half of Gestation

The objective of the present study was to determine the characteristics of Doppler flow velocity wave forms in branch pulmonary arteries in relation to gestational age. A total of 111 singleton normal pregnancies were studied during the second half of pregnancy using a combined color-coded Doppler and two-dimensional real-time ultrasound system. Pulsed Doppler measurements of the most proximal branch of the right or left pulmonary artery were attempted during fetal apnea from a transverse cross-section of the fetal chest at the level of the cardiac four-chamber view after visualization with color Doppler. The success rate in obtaining the pulmonary arterial wave form was 85%. The wave form displayed a rapid systolic velocity acceleration, followed by an initially rapid but then more gradual velocity deceleration which was interrupted in most cases by a short reversed flow interval at the beginning of the diastolic phase of the cardiac cycle. The diastolic phase was characterized by forward flow. Peak systolic, end-diastolic and time-averaged velocity, pulsatility index, and systolic integral remained constant during gestation. Changes in vessel diameter or compliance may play a role in this. A gestational age-dependent rise was established for peak diastolic velocity, diastolic integral, and early peak diastolic reverse flow, whereas a gestational age-determined decline was found for the peak systolic/peak diastolic ratio. Fetal heart rate demonstrated a statistically significant increase relative to gestational age. However, the observed relation between the flow velocity wave form parameters, pulsatility index calculations, and gestational age was independent of fetal heart rate. It is speculated that peak diastolic velocity, diastolic integral, and peak systolic/peak diastolic ratio rather than the pulsatility index are useful in detecting gestational age-related changes in human fetal pulmonary vascular resistance.

Behavior-state-dependent changes in human fetal pulmonary blood flow velocity waveforms

OBJECTIVE To establish the influence of fetal behavior states on venous and arterial pulmonary blood flow velocity waveforms in the normally developing term fetus. METHODS The relation between venous and arterial pulmonary blood flow velocity waveforms and fetal behavior states was investigated in 18 normal term fetuses. Recordings of the venous pulmonary blood flow velocity waveforms were obtained just proximal to the entrance in the left atrium, and the arterial pulmonary blood flow velocity waveforms were taken from the most proximal branch of the pulmonary artery in the same lung using color Doppler imaging. Time-averaged peak systolic, peak diastolic, and end-diastolic flow velocity; peak systolic to peak diastolic ratio; pulsatility index; and fetal heart rate were calculated from both venous and arterial Doppler recordings obtained during behavior states 1F (quiet sleep) and 2F (active sleep). Fetal behavior states were determined from combined recordings of fetal eye and body movements. RESULTS Recordings of sufficient quality for analysis were obtained from ten fetuses. Venous pulmonary blood flow velocity waveforms demonstrated a statistically significant increase in time-averaged peak diastolic and end-diastolic velocity during fetal behavior state 2F. No behavior-state-related changes were observed for the arterial pulmonary blood flow velocity waveform. CONCLUSION The data suggest an increased pressure gradient between the pulmonary venous system and the left atrium during behavior state 2F. Flow velocity waveforms from the proximal arterial pulmonary branch are independent of behavioral state.

WS15‐06Doppler ultrasonography of the human fetal pulmonary circulation and its role in the prediction of pulmonary hypoplasia

Objectives

P21Fetal liver volume in normal and reduced fetal growth

Background