Color Doppler flow mapping of fetal heart

Color Doppler flow mapping of fetal heart was performed in 582 fetuses between 16 and 38 weeks of gestation. Congenital heart diseases were excluded in 522 fetuses correctly. In 59 fetuses structural and/or functional cardiac abnormalities were diagnosed. In one fetus small multiple ventricular septal defects were missed. The most important additional information obtained by color Doppler flow mapping was: (1) Diagnosis of insufficiencies of atrioventricular valves; (2) Demonstration of turbulent high velocity jet in stenosis of semilunar valve; (3) Reverse flow in ascending aorta in atresia of aortic valves and on ductus arteriosus and main pulmonary artery in atresia of pulmonary valves; (4) Reverse perfusion of ductus arteriosus and main pulmonary artery as well as an antegrade turbulent high velocity jet in severe pulmonary stenosis as part of tetralogy of Fallot; (5) Bidirectional interventricular shunting of blood in ventricular septal defect. Color Doppler flow mapping allows rapid screening for flow abnormalities of the fetal heart. Exact localisation of sample volume by pulsed wave Doppler in area of abnormal flow pattern is possible, thus significantly reducing the Doppler examination time. The accuracy of prenatal diagnosis of congenital heart diseases is improved by application of color Doppler flow mapping, in particular in presence of complex cardiac defects.     

Doppler velocimetry and fetal heart rate studies in nephropathic diabetics.

OBJECTIVES: Our objectives were to determine in pregnancies complicated by diabetic nephropathy (1) if impedance to flow in the uterine and umbilical arteries is normal and (2) if these fetuses are hypoxemic and acidemic and if they have decreased fetal heart rate variation and Doppler blood flow redistribution. STUDY DESIGN: In a cross-sectional study at the Harris Birthright Research Centre for Fetal Medicine, London, serial assessment of fetal heart rate variation and Doppler velocimetry of the placental and fetal circulations was undertaken in six pregnancies complicated by diabetic nephropathy. In all cases cordocentesis was performed within 24 hours before delivery for the measurement of umbilical venous blood gases. RESULTS: Cordocentesis demonstrated these fetuses to be hypoxemic and acidemic. The fetal heart rate variation was decreased; however, impedance to flow in the uterine artery was normal, and increased impedance to flow in the umbilical artery with evidence of blood flow redistribution was observed in only one case. CONCLUSIONS: Fetal hypoxemia and acidemia in pregnancies complicated by diabetic nephropathy is not a consequence of impaired placental perfusion, and the degree of metabolic derangement may be obscured by the apparent normal growth and failure of these fetuses to demonstrate blood flow redistribution.     

Studies on cross correlation coefficient of fetal heart rate and fetal movement signals detected by ultrasonic Doppler fetal actocardiograph

Cross correlation coefficients of fetal heart rate (FHR) and fetal movement (FM) signals detected by ultrasonic Doppler actocardiograph were studies. Actocardiographic output was stored in a floppy disk through an AD converter. The parameters for every 5 minute period were calculated in 461 periods for 68 normal pregnant women at 14 to 41 weeks of gestation. 1) Between FHR acceleration (ACC) and the maximum coefficient, the averages for the maximum coefficients in 5 minute periods without and with ACC were 0.141 and 0.275, respectively. The respective lag time averages were 13.1 and 7.6 seconds. These results may indicate that the FHR ACC temporarily follow FM with a time lag of several seconds in the active state. 2) The largest value for the maximum coefficients and the lag times in each examination were investigated according for each gestational week. The coefficients increased and the lag times decreased as gestation advanced. 3) The coefficients in the periods showing typical fetal breathing movement and fetal hiccups were very small. Periodic fetal suckling observed with real-time B mode showed large coefficient with a 3 sec' delay in FM.     

Fetal Doppler Hypoxic index for the prediction of abnormal fetal heart rate at delivery in chronic fetal distress

OBJECTIVE: To design a Doppler Hypoxic index (HI), which takes into account both the duration and the intensity of fetal flow redistribution (i.e. hypoxia) for predicting the occurrence of abnormal fetal heart rate (FHR) at delivery. METHOD: Sixty-six pregnancies with hypertension and/or growth retardation (IUGR) were investigated (age: 23+/-5 years; primigravidas: 30%, CS 59%; hospitalisation: 10+/-8 days, IUGR (<10 c) 82%, intensive care 23%, fetal death 1). Umbilical (URI) and cerebral (CRI) Doppler resistance indices, and the C/U ratio (CRI/URI) were measured every 2 days from admission to delivery. HI was calculated by summing the daily %C/U reduction (in % from normal cut-off limit 1.1) over the period of observation (or mean C/U reduction in % from 1.1 x number of days of observation). Doppler C/U and HI were compared with fetal heart rate (FHR) traces, and perinatal data. RESULTS: HI > 160% was associated with abnormal FHR in 80% of the cases (PPV = 87%, NPV = 88%). HI > 160% predicted the occurrence of abnormal FHR 8+/-6 days before they happened. CONCLUSION: A combination of intensity and duration of the fetal flow redistribution (i.e. hypoxia) evaluated by Doppler is correlated with the occurrence of abnormal fetal heart rate.     

Prenatal diagnosis of fetal heart failure in twin reversed arterial perfusion syndrome

Diagnosis of twin reversed arterial perfusion (TRAP) syndrome is a rare fetal anomaly that can be misdiagnosed on prenatal ultrasound. We confirmed the use of colour-flow Doppler for prenatal diagnosis of TRAP syndrome and used serial fetal echocardiography for non-invasive evaluation of the fetus. A patient with twin intrauterine pregnancy was referred to our centre with suspected intrauterine fetal demise following a 16 week ultrasound. Serial colour-flow Doppler ultrasonography demonstrated retrograde arterial flow in an acardiac twin. Following diagnosis of TRAP syndrome, serial fetal echocardiography was employed to follow the normal twin for signs of heart failure, including right atrial dilation, tricuspid regurgitation and pericardial effusion. When early signs of fetal heart failure were suspected a viable female infant was delivered at 32 weeks' gestation. We suggest that serial fetal echocardiography represents a non-invasive approach that can be used to follow fetal cardiac function of the normal twin in TRAP syndrome.     

Observations on perinatal heart rate monitoring. II. Quantitative unreliability of Doppler fetal heart rate variability

Fifty-three fetal heart rate (FHR) tracings obtained by direct ECG monitoring during labor and 24 simultaneous external Doppler FHR tracings were analyzed for the quantitative assessment of baseline FHR variability. The beat-to-beat difference in FHR subsumed by 90% of all beat-to-beat changes within a tracing was taken as the index of variability of that tracing. This index correlated well with the visual assessment of variability for both internal ECG records (Spearman rank correlation coefficient, rs, = 0.71) and external Doppler records (rs = 0.78). However, there was no correlation between the variability index of the Doppler FHR records and that of simultaneous ECG FHR records (r = 0.11, p greater than 0.6). This finding casts doubt on the use of the presence of "normal" FHR variability as a sign of fetal well-being during antepartum FHR monitoring with current Doppler equipment.     

Plasma volume, umbilical artery Doppler flow, and antepartum fetal heart testing in high-risk pregnancies

The purpose of this clinical study is to investigate the diagnostic value of plasma volume (PV), nonstress test (NST), contraction stress test (CST), and umbilical artery Doppler (UAD) in detecting fetal compromise in 81 patients (83 fetuses) at risk for fetal growth retardation. Neither PV nor UAD studies were used in the clinical management. There were two stillbirths and three neonatal deaths for a perinatal mortality of 6%. Twenty-seven infants (32.5%) were small for gestational age (SGA), seven (8.6%) had cord pH 7.20 or less, and five (6.2%) had 5-minute Apgar scores less than 7. Overall, PV had the highest sensitivity and NST the highest specificity regarding delivery of SGA infants. The positive and negative predictive values for infants with low cord pH and low Apgar scores were similar among the various tests. There were nine fetuses with zero or reverse diastolic flow: seven were SGA (four perinatal deaths) and all of them had both nonreactive NST and positive CST. The other two infants were appropriate for gestational age with all other tests being normal. Antepartum fetal heart rate testing appears to be similar to other tests in predicting poor fetal outcome in high-risk pregnancies.     

Transvaginal pulsed Doppler velocimetry in fetal arteries

Summary Transabdominal pulsed Doppler velocimetry in fetal arteries might be difficult with extreme obesity, anhydramnios, cord presentation and an unfavourable position of the fetal head. A vaginal transducer gets closer to the presenting part of the fetus and therefore has advantages for Doppler velocimetry in fetal arteries.     

Evaluation of fetal heart rate artifacts, hemodynamics and digoxin treatment in fetal tachyarrhythmia by Doppler measurement of fetal blood flow--case report of a pre-excitation syndrome

A fetal cardiac arrhythmia may cause misleading fetal heart rate tracings with unreliable signs of fetal distress. Assessment of such artifacts and of the hemodynamic relevance of a fetal arrhythmia by alternative methods is necessary for management and therapy. A 28-year-old healthy woman was referred at 30 weeks of gestation because of fetal tachy-brady-arrhythmia, but cw-Doppler assessment of umbilical artery blood flow revealed periods of pseudobradycardia during bigeminal and trigeminal fetal pulse. FHR turned to regular tachycardia, and transplacental digitalization was started. Between 32 and 34 weeks the patient discontinued her digitalis intake, and a fetal pericardial effusion indicated subsequent cardiac failure. Serial pulsed Doppler measurements of fetal aortic blood flow were performed and imminent heart failure was recognized after the digitalis was discontinued and before a pericardial effusion occurred. Furthermore, improvement of fetal cardiac performance secondary to restarting digitalis and also prior to resolution of the pericardial effusion. After spontaneous delivery a Wolff-Parkinson-White syndrome was diagnosed, and continuation of digoxin treatment was indicated. Cw-Doppler assessment of umbilical artery blood flow was a suitable method to evaluate questionable FHR recordings, and pulsed Doppler allowed monitoring of the therapeutic effect of transplacental digitalization by serial measurements of fetal aortic blood flow.     

Evaluation of fetal movements with ultrasonic Doppler fetal actograph

Fetal movements in each trimester were recorded objectively and continuously with an ultrasonic Doppler actograph that enables simultaneous tracing of fetal heart rate (FHR) and fetal movement (FM). The record with this method was compared with those of the ultrasonic B-mode and M-mode respectively. The onset of FM signal bursts and FHR acceleration was nearly synchronous and the transitory FHR increase associated with FM signal bursts showed a linear amplitude increment along with the progress of gestation. Fetal hiccup movements were recorded from 24 weeks of gestation and lasted between 4.3 minutes and 17 minutes with a rate of 25 to 28 per minute. No FHR acceleration was recognized in such movements. Maternal perception was 67.7% on average of FM signal bursts. Fetal movements in early pregnancy were detected in the 11th week of gestation (CRL 54 mm). Long-term recording of fetal movements was carried out between 9:30 and 17:00 and the alternation of active and resting phases was investigated. The resting phase lasted 20 minutes on average, (range, 10 to 36 minutes). The fetal activity was not influenced by the maternal food intake. It is clinically significant to evaluate the change in fetal movements objectively and continuously.