Sinusoidal fetal heart rate pattern with intrapartum fetal death

A case of sinusoidal fetal heart rate pattern with intrapartum fetal death is presented. This pattern has been observed infrequently during both the antepartum and intrapartum periods. Not all sinusoidal patterns may be ominous. A reasonable plan of management includes maternal position change, oxygen administration, scalp sampling and preparation for immediate delivery.     

Dexamethasone and fetal heart rate variation

OBJECTIVE: To determine the effect of maternal administration of dexamethasone on fetal heart rate and its variation. DESIGN: Retrospective analysis of computerised data derived from cases studied over three years. SETTING: High risk pregnancy unit, John Radcliffe Hospital, Oxford. SUBJECTS: Twenty-eight pregnant women, at 27 to 32 weeks of gestation, to whom dexamethasone was given to accelerate pulmonary maturation in the expectation of preterm delivery. METHODS: Dexamethasone (two doses of 12 mg intramuscularly, 12 h apart) was given on 51 occasions at weekly intervals (one to four occasions per patient). Complete data were available for cardiotocograph analysis from computerised measurement of fetal heart rate variables for two days before and four days after dexamethasone and, in 19 women, measurements of umbilical arterial flow velocity waveforms before and after dexamethasone. RESULTS: In 10 pregnancies without fetal distress there was a highly significant (P < 0.01) transient rise in short term fetal heart rate variation after dexamethasone administration, from means (SE) 6.4 (0.28) to 9.8 (0.4) ms. In 18 pregnancies with subsequent delivery for fetal distress (abnormal fetal heart rate pattern) and high umbilical arterial resistance index [mean 0.93 (0.06 SE)], the rise in short term fetal heart rate variation was less (P < 0.01), from mean (SE) 5.4 (0.26) to 6.1 (0.48) ms. In a further case of discordant twin pregnancy, the larger twin continued to respond to dexamethasone administrations with a rise in fetal heart rate variation for five weeks; the smaller twin, with maintained tachycardia and reduced umbilical arterial end-diastolic flow velocity, failed to respond after the first two weeks. CONCLUSION: The results show that maternal dexamethasone administration normally causes a rise in fetal heart rate variation for up to a day. This rise is reduced in pre-eclampsia or intrauterine growth retardation, associated with a reduction in umbilical flow, perhaps because of a consequential lower concentration of steroid in the fetus. The results contrast with those for betamethasone which has been reported to reduce fetal heart rate variation.     

Gender does not affect fetal heart rate variation

There is a widespread but erroneous view among the lay public that there is a difference in the baseline fetal heart rate between male and female fetuses. It has been suggested that this perception might reflect an actual difference in fetal heart rate variability. Therefore, we studied the fetal heart rate variation in 79 white European women using the Sonicaid System 8002 computer. Fourty-four of the fetuses were male and 35 were female. There was no significant gender difference in any measured aspect of fetal heart rate variation.     

Recording fetal heart rate as a behavioral measure.

Employed the fetal EKG with 4 electrodes placed on the maternal abdomen 1 just above the symphysis pubis, and the other across the abdomen at the level of the fundus uteri. The relationship between maternal and fetal heart rates were explored by also recording the maternal EKG. Difficulties in measuring fetal heart rate are discussed and possible solutions presented. It is concluded that fetal heart rate is a difficult but possible measure for exploration of fetal behavior. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonstressed fetal heart rate monitoring in the antepartum period

The role of nonstressed monitoring of the fetal heart rate (HR) in determining fetal well-being during the antepartum period was assessed in 125 high-risk patients. Observations on HR, variability, and HR response to fetal movement (FM) and uterine contractions (UC) over a 30 minute period were made with an external microphone and tocotransducer. A total of 625 tests were performed; the earliest gestation tested was 28 weeks, and the latest was 46 weeks. A reactive pattern (variability greater than 6 b.p.m. and accelerations with FM) appears to be a reliable indicator of fetal well-being. All the 51 fetuses exhibiting this pattern survived. This group also had the lowest incidence of neonatal complications. On the other hand, of the babies who failed to show variability greater than 6 b.p.m. or accelerations with FM (nonreactive pattern), 40% died in the perinatal period. Thirty-five patients showed features of both a reactive and nonreactive pattern (combined pattern). Poor outcome in this group was confined to those in whom the majority of the pattern was nonreactive. An undulating HR pattern with virtually absent variability (sinusoidal pattern) was found in 20 Rh-sensitized fetuses, 50% of whom died in the perinatal period. Bradycardia and tachycardia were not found to be reliable signs of fetal distress antepartum. Of the 12 fetuses who died during observation, six showed late decelerations with spontaneous UC but all showed diminished variability. The close correlation between nonstressed patterns and neonatal outcome demonstrated by this preliminary study warrants further use of this technique for fetal evaluation.     

Fetal heart rate patterns in postasphyxiated fetal lambs with brain damage

OBJECTIVE: We previously showed that in asphyxiated fetal lambs the duration of hypotension correlated well with the severity of histologic damage to the brain, whereas the duration of bradycardia did not. This study compares fetal heart rate patterns with the degree of histologic damage to the brain. STUDY DESIGN: Twelve chronically instrumented near-term fetal lambs were subjected to asphyxia by umbilical cord occlusion until fetal arterial pH was <6. 9 and base excess was <-20 mEq/L. An additional 4 fetuses served as sham-asphyxia controls. Fetal heart rate (from electrocardiogram), arterial blood pressure, fetal breathing movements, and electrocorticogram were continuously monitored before, during, and for 72 hours after asphyxia. Fetal brain histologic features were categorized as mild (group 1, n = 5), moderate (group 2, n = 4), and severe (group 3, n = 3). Long-term fetal heart rate variability expressed as amplitude range was assessed visually every 5 minutes from 30 minutes before asphyxia until 2 hours of recovery and at 6, 12, 24, 48, and 72 hours of recovery. RESULTS: Long-term fetal heart rate variability amplitude decreased from 32 +/- 17 beats/min (mean +/- SEM) preocclusion to 4 +/- 13 beats/min at the end of occlusion (P <.001) without significant differences among the 3 groups. During 10 to 45 minutes of recovery, the long-term variability of group 1 was significantly greater than that of groups 2 and 3. At 24 to 72 hours of recovery, the long-term variability of groups 1 and 2 was significantly higher than that of group 3, which was almost 0. The "checkmark" and sinusoidal fetal heart rate patterns were observed during the recovery period in groups 2 and 3. CONCLUSIONS: Decreased long-term fetal heart rate variability and the "checkmark" and sinusoidal fetal heart rate patterns were indicators of the severity of asphyxial histologic damage in the fetal brain.     

Intermittent sinusoidal heart rate pattern in vagotomized fetal lambs

OBJECTIVES: Our aims were to investigate the relationship between the dose of arginine vasopressin and the pattern and duration of arginine vasopressin-induced sinusoidal fetal heart rate and to elucidate the correlation between intermittent sinusoidal heart rate and fetal sleep cycle. STUDY DESIGN: Sinusoidal heart rate pattern was induced by intravenous arginine vasopressin infusion at doses from 2 to 78 mlU/min into 11 chronically instrumented fetal lambs with bilateral cervical vagotomy. Appearance and frequency of sinusoidal heart rate, intermittent sinusoidal heart rate, and persistent sinusoidal heart rate were observed along with fetal tracheal pressure and electrooculogram. RESULTS: Intermittent sinusoidal heart rate response to low, medium, and high doses of arginine vasopressin appeared in 73.3%, 50.0%, and 33.3% of experiments, respectively. Intermittent sinusoidal heart rate appeared more frequently than persistent sinusoidal heart rate with lower doses (p < 0.02). When intermittent sinusoidal heart rate was induced, the incidence of sinusoidal patterns significantly increased during non-rapid-eye-movement sleep in comparison with rapid-eye-movement sleep (p < 0.01). CONCLUSIONS: Appearance of sinusoidal heart rate seems to be related to the dose of arginine vasopressin infused. Appearance of sinusoidal heart rate is also influenced by fetal sleep cycle; sinusoidal heart rate is more likely to appear during non-rapid-eye-movement sleep than during rapid-eye-movement sleep. These results support the hypothesis that persistent sinusoidal heart rate correlates with severity of stress.     

The response of the fetal heart rate of amniocentesis

Fetal heart rate monitoring during 107 amniocenteses suggested that acceleration of the fetal heart rate indicated fetal well-being. Eight out of the 19 fetuses who did not show this response (as against 2 out of the 88 others) had a low Apgar score at birth.     

A maternal complex partial seizure in labor can affect fetal heart rate

We describe a 33-year-old woman who had a complex partial seizure during labor. Intrauterine pressure catheter and fetal heart monitoring during the seizure revealed a strong, prolonged uterine contraction and simultaneous significant fetal heart rate deceleration for 3.5 minutes. This patient demonstrates that complex partial seizures may result in uterine hyperactivity during labor, which may result in fetal hypoxia.     

Acceleration patterns of the fetal heart rate before and during labour

In infants in whom accelerations of the fetal heart rate were present during the first stage of labour, the incidence of low Apgar scores was significantly less than in those in whom accelerations were not present. Absence of acceleration patterns during the contraction stress test (CST) was associated with a lower birth weight. In patients in whom acceleration patterns were observed during a positive CST, fetal distress occurred in the minority of subsequent labours. When accelerations as well as late decelerations are observed during a CST, the possibility of a false positive test should be excluded.     

Pearson's fetal movement count (FMC) and antepartum fetal heart rate testing (AFHRT) for antepartum fetal well-being

To evaluate the accuracy of Pearson's fetal movement count (FMC) and antepartum fetal heart rate testing (AFHRT) in 380 high risk pregnancies at Rajavithi Hospital in 1994, the result of the 4 test FMC, AFHRT, FMC + AFHRT (serial test), and FMC + AFHRT (parallel test) were compared in sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false positive rate (FPR), false negative rate (FNR) and accuracy. All tests had equal specificity and FPR. FMC + AFHRT (serial test) had the highest value of sensitivity (66.67%) but lowest value of FNR, NPV and accuracy (33.33%, 40%, 72.73% respectively). PPV was 100 per cent in AFHRT and FMC + AFHRT (serial test). FMC might be used as a first line antepartum fetal well being screening test.     

Clinical and ultrasonographic features of dextroposition of the fetal heart

OBJECTIVE: Our purpose was to characterize the findings associated with dextroposition of the fetal heart. STUDY DESIGN: A fetal echocardiography database was retrospectively searched from January 1990 through December 1996 to identify all cases referred or diagnosed with dextroposition of the fetal heart. Dextroposition was defined as most of the normally connected fetal heart found on the right side of the fetal chest. Intracardiac and extracardiac fetal anomalies were reviewed. All available karyotypes and postnatal examinations were reviewed. RESULTS: During the study period 2882 fetal echocardiograms were performed, of which 297 (10.3%) were abnormal. Of these, 14 had dextroposition. Associated anomalies included atrioventricular canal (29%), diaphragmatic hernia (21%), and aneuploidy (14%). Isolated dextroposition with no other significant anomalies was seen in only 1 case. In another, no anomalies were noted except for suspected agenesis of 1 lobe of the right lung; karyotype and postnatal evaluation revealed no other abnormalities in both cases. CONCLUSIONS: Dextroposition of the fetal heart was seen in 0.5% of our fetal echocardiograms and was associated with significant anomalies in 86% of our cases. When diagnosed, a targeted ultrasonogram, fetal echocardiogram, and karyotype should be offered.     

Evaluation of the accuracy of a new ultrasonic fetal heart rate monitor

An indirect Doppler fetal monitoring system has been developed and validated by computer comparison of simultaneous fetal heart rate (FHR) with Doppler and scalp ECG of high-risk patients during labor. The difference in measurement of FHR averaged 0.3 b.p.m., and 93 per cent of the Doppler FHR measures were within 10 b.p.m. of the ECG FHR. If interinstrument difference is discounted, 96 per cent were within 10 b.p.m. All types of decelerations and variability were well approximated. Doppler FHR from the instrument described may be relied upon as valid clinical information and may be obtained from over 90 per cent of labor patients with 93 per cent accuracy.     

"Prediction" of the one-minute Apgar score from fetal heart rate data

The value of any fetal monitoring technic is in its ability to predict infant outcome. In the present study, the ability of fetal heart rate (FHR) monitoring data to "predict" a measure of short-term infant outcome, the 1-minute Apgar score, was evaluated using univariate and multivariate statistical analyses. Of 61 monitored high-risk infants, 46 had high (7 to 10) and 15 had low (1 to 6) 1-minute Apgar scores. Computer analysis of FHR/intrauterine pressure (IUP) data for these 61 infants revealed that the infants with low Apgar scores had more than the expected number of late decelerations (LD). Using a threshold of ten LD and univariate analysis, 74% of the infants could be properly classified for high or low Apgar scores, but 60% of the infants with low Apgar scores were not identified. Using discriminant function (multivariate) analysis for the numbers of LD and uterine contractions, 47% of the depressed infants were appropriately identified and simple risk scoring equations were devised. Using additional observation vectors, including the number of accelerations and early decelerations, 67% of the depressed infants could be identified. The results of this study suggest that using multiple observation vectors improves the predictive capacity and, thus, the value of fetal monitoring data. Clinical experience suggests that the value of monitoring data can be further enhanced by simultaneous evaluation of other observation vectors from additional perinatal data sets using the technics of this study.     

Assessing sequential irregularity of both endocrine and heart rate rhythms

The quantification of subtle patterns in sequential data, and their changes, has considerable potential utility both in analysis of hormonal secretory dynamics, and of fetal heart rate rhythms. Approximate entropy, a recently developed statistic quantifying serial irregularity, has been applied in both these settings, and has yielded a number of new findings. Among endocrine applications, approximate entropy increases with increasing age for luteinizing hormone and follicle stimulating hormone, for both women and men, indicating greater irregularity (more apparently random dynamics) in the older groups; for the luteinizing hormone-testosterone axis, both irregularity and asynchrony increases accompany advancing age for men. These findings produce a means to potentially predict time until menopause onset, the efficacy of infertility drugs, and also provide firm quantitative support of a partial male menopause. In fetal monitoring, antepartum, and postnatal heart rate studies, approximate entropy consistently detected subtle shifts in heart rate rhythmicity, with greater regularity clinically corresponding to compromised physiology in all settings. Both the capability of approximate entropy to quantify rhythm changes undiscernible by auscultation, and a continuum interpretation linking per-individual antepartum, perinatal, and postnatal heart rate analyses provide considerable potential enhancement to the present clinical utility of fetal monitoring.     

Effect of dexamethasone and betamethasone on fetal heart rate variability in preterm labour: a randomised study

OBJECTIVE: To compare the effects of betamethasone and dexamethasone on fetal heart rate in appropriately grown fetuses. METHODS: Eighty-two pregnant women (97 fetuses) with preterm labour were randomly allocated to receive betamethasone (n=42) or dexamethasone (n=40) for fetal lung maturation in a nonblinded fashion. Computerised cardiotocogram (CTG) parameters were compared before, during and after treatment. RESULTS: A decrease in fetal heart rate variability was found with betamethasone but no significant changes were found with dexamethasone. Fetal heart rate variability returned to pre-treatment values within a week after cessation of treatment with betamethasone. Neonatal outcome was similar in the two groups. CONCLUSIONS: These findings might prove useful in the management of compromised fetuses with decreased fetal heart rate variability in which the CTG should be used together with other parameters to assess fetal wellbeing during corticosteroid treatment. Dexamethasone may be preferable as the drug of choice since it was associated with significantly less alteration in fetal heart rate variability compared with betamethasone.     

Prevalence of fetal heart rate decelerations in self-referred low-risk patients in the third trimester

We tested the hypotheses that fetal heart rate decelerations are present during the third trimester in most low risk pregnant women, the prevalence of decelerations is a function of the length of time fetal heart rate monitoring occurs and their presence is not associated with an adverse prognosis. We performed a retrospective chart review of 114 self-referred low-risk pregnant patients who presented to the labor and delivery triage area of a tertiary care hospital at 26-41 weeks gestation. None required admission to the hospital. The control group consisted of patients who delivered immediately before and after the delivery of the study patient. Normal long-term variability and fetal baseline heart rate were found in all electronic fetal monitoring tracings. Accelerations were present in 91% and decelerations in 65% of patients. There was no correlation between length of time of monitoring and the incidence of decelerations. At delivery, there were no differences in birthweight, gestational age, 5-min Apgar scores or cord pH between the control and study patients. Variable decelerations were a common finding in the third trimester of low-risk pregnant patients who self referred to labor and delivery triage. They were not prognostic of an adverse perinatal outcome.     

Changes in blood velocities of fetal circulation in association with fetal heart rate abnormalities: effect of sublingual administration of nifedipine

Nifedipine has been used to treat hypertension in pregnancy, and does not influence fetal or uteroplacental circulations in patients with preeclampsia. A 29-year-old multi-gravid woman presented at 32 weeks' gestation with significant elevation of her blood pressure. After sublingual administration of nifedipine, the blood pressure decreased from 208/122 to 136/96 mm Hg at 30 minutes. In her growth-retarded fetus with abnormal flow velocity waveforms, pulsatility index values for middle cerebral artery and umbilical artery did not change; however, peak systolic velocities, end-diastolic velocities, and time-averaged mean peak velocities for these arteries became significantly elevated. Simultaneously, severe variable decelerations and late decelerations occurred. The adverse effect of nifedipine on fetal circulation might occur in a growth-retarded fetus with abnormal flow velocity waveforms.     

Denoising of the fetal heart rate signal with non-linear filtering of the wavelet transform maxima

The fetal heart rate (FHR) signal provides valuable information for fetal development and well-being. However, the FHR traces derived from present-day ultrasound cardiotocographs are not of the desired quality. The paper applies the wavelet transform (WT) in order to denoise effectively the FHR signal. The denoising procedure analyses the evolution of the WT maxima across scales. The singularities of the signal create wavelet maxima with different properties from those of the induced noise. Since it is difficult to formulate precise rules that distinguish between the wavelet maxima of the FHR signal from those of the noise we have trained a neural network for this classification task. The neural network draws out successfully the noise induced wavelet maxima. An improved FHR signal can be obtained from the coarser wavelet approximation signal component and the filtered wavelet maxima by means of the inverse dyadic wavelet transform. Also, feature extraction and processing algorithms can be defined on the denoised wavelet coefficients (instead of on the original signal).     

Human fetal heart rate dishabituation between thirty and thirty-two weeks gestation

Few studies of human fetal habituation have included dishabituation procedures (i.e., assessment of the reemergence of a habituated response) to determine if response decrements are the result of reevaluation of information (a brain process) or fatigue of peripheral receptors. The purpose of this study is to describe the ability of the human fetus to learn and recall information with procedures to assess the central nervous system. Fetal heart rate (FHR) of 84 fetuses between 30 and 32 weeks gestational age was examined in response to 3 series of vibroacoustic (VA) stimuli presented at pseudorandom intervals of 25-45 s over the head of the fetus. Responses to the first series of 15 stimuli (S1) were compared with an identical second series of 15 stimuli (S1) presented over the head of the fetus. Between the 2 series, a novel (dishabituating) VA stimulus (S2) was presented, differing from S1 in intensity and frequency. The third series of S1s was applied to the mother's thigh as a control for possible maternal responses to the stimulus. Prestimulus FHR was computed during a 5 s interval before each stimulus, and mean FHR was computed during the intertrial interval (average FHR). The response to S1 during the first series of trials (1-15) produced a sustained rise in both prestimulus and average FHR, r(83) = .90, p < .001. After the novel S2 (trial 16) the rate of change was attenuated for average FHR, r(83) = .12, ns, to S1 for trials 17-31 but not prestimulus FHR, r(83) = .50, p < .001. The decrease in FHR response was reestablished when stimulation was applied to mother's thigh, trials 32-41, r(83) = .92, p < .001. A significant habituation pattern across trials was observed for the first series of S1s when prestimulus HR was subtracted from each preceding average FHR value (delta FHR). After the single novel stimulus (S2), the FHR response to S1 reemerged. All combinations of beginning and ending series slopes were compared, and only the rate of change during the last 4 trials of the initial presentation of S1 and the first 4 trials after the novel stimulus was significant, F(1, 82) = 9.21, p < .003. Uterine contractions collected from the continuous record were not related to the presentation of the novel stimulus, chi 2(1, N = 84) = 0.59, p < .50, ns, or delta FHR slope after the novel stimulus, chi 2(9, N = 84) = 10.52, p < .50, ns. These results established that the 32 week human fetus is capable of detecting, habituating, and dishabituating to an external stimulus and support the premise that areas of the human fetal central nervous system critical for detecting and discriminating information and for learning and memory have developed by the early third trimester.