Doppler flow velocity waveforms in the fetal cardiac outflow tract: Reproducibility of waveform recording and analysis

__Abstract__ Reproducibility of flow velocity waveform recording and analysis was studied at fetal cardiac level (ductus arteriosus, pulmonary artery and ascending aorta) in 42 normal pregnancies. The flow velocity parameters studied were the peak systolic velocity (PSV), acceleration time (ACT), acceleration velocity (ACV), average velocity (AV) and flow velocity integral (FVI). In each patient, two consecutive measurements were performed (time delay 15 min) and of each measurement two hardcopies were analysed. A high reproducibility was achieved for the PSV, AV and FVI in all vessels studied; the coefficients of variation between readings of hardcopies were ≤3%, and the coefficients of variation between tests within patients were ≤7%. A moderate reproducibility was achieved for the ACT in the ascending aorta and pulmonary artery; the variation between tests was large for the ductus arteriosus. The reproducibility of the ACV was poor

Three-dimensional sonographic measurement of normal fetal brain volume during the second half of pregnancy

Objectives: This study was undertaken to develop a three-dimensional (3D) ultrasound method of measuring fetal brain volume. Study design: Serial 3D sonographic measurements of fetal brain volume were made in 68 normal singleton pregnancies a

Doppler colour flow imaging of fetal intracerebral arteries relative to fetal behavioural states in normal pregnancy

In 14 normally developing term fetuses, the relationship between the blood flow velocity waveforms at cerebral arterial level (internal carotid artery, anterior, middle and posterior cerebral artery) and fetal behavioural states was studied using Doppler colour flow imaging. Behavioural state dependent changes in absolute flow velocities occurred in all vessels, except for the middle cerebral artery. These changes suggest preferential blood flow to the left heart resulting in increased flow to the cerebrum during fetal behavioural state 2F (active sleep) when compared with fetal behavioural state 1F (quiet sleep). The middle cerebral artery supplies the neocerebrum. This developing part of the cerebrum does not seem to take part in the regulation of fetal behaviour. In the internal carotid artery, an inverse relationship between peak systolic velocity and fetal heart rate could be established, which can be explained by a shorter rapid filling phase at raised fetal heart rate according to the Frank-Starling Law

Assessment of fetal heart rate variability and velocity variability by Doppler velocimetry of the descending aorta at 10-20 weeks of gestation

Objectives: Determination of gestational age-related modulations in fetal heart rate and descending aorta blood flow velocity in the early human fetus and comparison of aortic variability data with data obtained from the umbilical artery. It is hypothesized that these modulations present in the umbilical artery also occur in the descending aorta. Methods: Doppler studies of descending aorta velocity waveforms were performed at 10-20 weeks in 55 normal pregnant women. In 24 of the 55 women, Doppler recordings from both the descending aorta and the umbilical artery were collected. Absolute values and variability of fetal heart rate, peak systolic and time-averaged velocities were determined from flow velocity waveforms of at least 18 s in duration. Results: From 10 to 20 weeks of gestation, the descending aorta peak systolic and time-averaged velocities increased, whereas the fetal heart rate decreased. The descending aorta peak systolic variability also increased. However, the time-averaged velocity variability and the fetal heart rate variability remained constant during the study period. In the subset of 24 women, the fetal heart rate variability and velocity variability data from the descending aorta and umbilical artery were not significantly different. Conclusions: Reproducible fetal heart rate and velocity variability data can be derived from the descending aorta and umblilical artery. The increase in heart rate variability observed in the umbilical artery was not seen in recordings obtained from the descending aorta. Different fetal activity states may be the underlying mechanism for these heart rate variability discrepancies

Spontaneous abortion rate and advanced maternal age: Consequences for prenatal diagnosis

Abstract Maternal age related and procedure-related fetal abortion rates were studied in 384 women aged 36 and over scheduled for transabdominal chorionic villus sampling (TA-CVS) at 12-14 weeks of gestation. The pre-TA-CVS abortion rate within 30 days of intake (at 6-10 weeks of gestation) rose from 1·9% at age 35-36 years to 10·9% at 40 years and older. Women entering in the 6th week of gestation had a greater probability of aborting before TA-CVS than women entering after day 48. 26 women aborted spontaneously before TA-CVS, the majority of abortions occuring at 10-12 weeks. TA-CVS was done in 346 women. 11 pregnancies were terminated because of genetic anomalies, and 8 women had spontaneous fetal loss. These findings justify delaying prenatal diagnosis in older pregnant women until 12 weeks of gestation

Acutely altered hemodynamics following venous obstruction in the early chick embryo

In the venous clip model specific cardiac malformations are induced in the chick embryo by obstructing the right lateral vitelline vein with a microclip. Clipping alters venous return and intracardiac laminar blood flow patterns, with secondary effects on the mechanical load of the embryonic myocardium. We investigated the instantaneous effects of clipping the right lateral vitelline vein on hemodynamics in the stage-17 chick embryo. 32 chick embryos HH 17 were subdivided into venous clipped (N=16) and matched control embryos (N=16). Dorsal aortic blood flow velocity was measured with a 20 MHz pulsed Doppler meter. A time series of eight successive measurements per embryo was made starting just before clipping and ending 5h after clipping. Heart rate, peak systolic velocity, time-averaged velocity, peak blood flow, mean blood flow, peak acceleration and stroke volume were determined. All hemodynamic parameters decreased acutely after venous clipping and only three out of seven parameters (heart rate, time-averaged velocity and mean blood flow) showed a recovery to baseline values during the 5h study period. We conclude that the experimental alteration of venous return has major acute effects on hemodynamics in the chick embryo. These effects may be responsible for the observed cardiac malformations after clipping

Long-term follow-up of retrograde colonic irrigation for defaecation disturbances

Objective. Irrigation of the distal part of the large bowel is a nonsurgical alternative for patients with defaecation disturbance. In our institution, all patients with defaecation disturbances, not responding to medical treatment and biofeedback therapy, were offered retrograde colonic irrigation (RCI). This study is aimed at evaluating the long-term feasibility and outcome of RCI. Methods. Between 1989 and 2001, a consecutive series of 267 patients was offered RCI. All patients received instructions about RCI by one of our enterostomal therapists. Twenty-eight patients were lost to follow-up. A detailed questionnaire was sent by mail to 239 patients. The total response rate was 79% (190 patients). Based on the returned questionnaires it became clear the 21 (11%) patients never started RCI. The long-term feasibility and outcome of RCI was therefore assessed in the remaining group of 169 patients. Thirty-two patients were admitted with soiling, 71 patints with faecal incontinence, 37 patients with obstructed defaecation and 29 had defaecation disturbance after low anterior resection or pouch surgery. Results. According to the returned questionnaires, RCI was considered effective by 91 (54%) patients. Among patients with soling and faecal incontinence, RCI was found to be effective in, respectively, 47 and 41% of the subjects. Despite of the reported effectiveness, 10 (67%) patients with soiling and 5 (17%) patients with faecal incontinence decide to stop. Among patients with obstructed defaecation and those with defaecation disturbances after low anterior resection or pouch surgery the effectiveness of RCI was found to be 65 and 79%, respectively. None of these patients ceased their therapy. The overall succes-rate of long-term RCI was therefore 45%. Conclusions. Long-term RCI is beneficial for 45% of patients with defaecation disturbance. In the group of patients who considered RCI effective and beneficial, discontinuation of therapy was only observe among those with soiling and faecal incontinence