The application of fetal magnetocardiography (FMCG) to investigate fetal arrhythmias and congenital heart defects (CHD)

OBJECTIVES--Fetal magnetocardiography (FMCG), a new non-invasive diagnostic tool in the analysis of the electrophysiological changes of the heart, was selectively applied in cases of fetal arrhythmias and congenital heart defect (CHD) to demonstrate its value for diagnosis and prenatal management. METHODS--The FMCG was analysed and compared to the postnatal ECG in four cases of fetal arrhythmia [supraventricular tachycardia (two cases), complex tachy-/bradycardia (one case), ventricular extrasystoles (one case)] and a case of right heart hypoplasia diagnosed by established methods prior to investigation. RESULTS--A Wolf-Parkinson-White (WPW) syndrome was diagnosed by its characteristic features and the appropriate transplacental therapy chosen. The types of arrhythmia could be characterised in accordance with postnatal ECG findings and irregular conduction was demonstrated in association with a CHD. CONCLUSIONS--The use of the FMCG provides additional information to the common diagnostic tools that influence therapeutic decisions and thus contributes to optimal pre- and postnatal management.     

A new method in fetal heart electrophysiology - fetal magnetocardiography

Fetal magnetocardiography (fMCG) is used as a non-invasive method for registering the electrophysiological fetal heart activity. Superconducting quantum interference device-based magnetometers are currently used to make fMCG recordings. In contrast to fetal ECG, this method is independent of signal loss due to isolating factors such as, especially, the vernix caesaroa between the 27th and 34th weeks of gestation. We report about a term newborn with a third degree AV block, examined by this method.     

Pharmacologic therapy for fetal arrhythmias

Although great strides have been made in diagnosing fetal cardiac anatomic and functional abnormalities, in utero cardiac therapy is limited to the treatment of significant arrhythmias. The fetal prognosis may change if the dysrhythmia persists or if the condition results in intrauterine heart failure. When either complication is evident, intrauterine drug therapy may be indicated if the fetus is considered too immature for delivery. Information from case reports has shown several drugs to be useful to cardiovert the fetus, with digitalis being the pharmacologic agent used most often. At present, treatment consists mainly of transplacental administration of antiarrhythmic agents with the object of normalizing FHR and rhythm and abolishing, or preventing, fetal cardiac failure. Various agents have been used with variable success. More direct fetal therapy by intramuscular injection or umbilical vein infusion may replace unsuccessful indirect maternal therapy. It is unclear why some fetuses respond (or appear to respond) and others have hydrops and die in the absence of congenital heart disease or documented infection. With proper therapy, many fetuses survive and have a satisfactory prognosis, depending on the form of arrhythmia and the nature of any cardiac structural defects.     

Successful management of supraventricular tachycardia in a fetus using fetal magnetocardiography

We report a fetus at 33 weeks of gestation with supraventricular tachycardia, which was successfully managed by transplacental administration of an antiarrhythmic agent. Fetal magnetocardiography (fMCG) revealed supraventricular tachycardia of the long RP' tachycardia type. Transplacental administration of sotalol, instead of digoxin, was selected as the first-line drug, and it successfully converted supraventricular tachycardia to sinus rhythm. The diagnosis of the type of supraventricular tachycardia was confirmed by electrocardiography after birth. Sotalol was also effective after birth to maintain sinus rhythm. This case demonstrates that fMCG is potentially useful for prenatal differentiation of the type of supraventricular tachycardia and for prenatal treatment of fetal tachyarrhythmias.     

The coincidence of fetal magnetocardiography and direct electrocardiography in a case of fetal atrial flutter due to intracardiac tumor

OBJECTIVE: To demonstrate the coincidence of fetal magnetocardiography (FMCG) and fetal direct electrocardiography (FDECG) in a case of fetal atrial flutter (AF). METHODS: FMCG and FDECG using a fetal scalp electrode were recorded in the case of fetal AF at 41 weeks' gestation. RESULTS: FMCG revealed fetal AF with 2:1 atrioventricular block, which was also documented by FDECG using a fetal scalp electrode. The prenatal diagnosis was confirmed by postnatal electrocardiogram. Neonatal echocardiography revealed an intracardiac tumor on the left atrial septum. The tumor seemed to be the cause of AF. CONCLUSION: FMCG may provide the same information as a fetal electrocardiogram in the prenatal diagnosis of fetal AF.     

胎儿心律失常的诊疗进展

胎儿心律失常的性质与类型预示胎儿的转归并影响临床处理及预后。频发严重的胎儿心律失常或伴心脏结构缺陷的胎儿心律失常,可致不良围产儿结局。因此,早期发现、诊断高风险的胎儿心律失常并正确进行宫内干预,可改善胎儿预后。     

Prenatal diagnosis of a long QT syndrome by fetal magnetocardiography in an unshielded bedside environment

OBJECTIVE: The potentially life threatening long QT syndrome should be diagnosed during pregnancy to improve perinatal care. METHODS: A patient with a family history for a hereditary long QT syndrome presented at 30 weeks of her first pregnancy with fetal bradycardia and a narrow oscillation bandwidth on cardiotocography without structural abnormalities of the fetal heart. Fetal magnetocardiography was performed with a prototype biomagnetometer/gradiometer device in a magnetically unshielded environment. The cardiac time intervals were determined in the averaged PQRST complex. RESULTS: The QT time and the frequency-corrected QTc showed a marked prolongation to 380 ms and 0.52 s, respectively. The findings were confirmed in the postnatal electrocardiogram after spontaneous term delivery in a perinatal center. The causative mutation on chromosome 11 had been passed on to the newborn from his mother. CONCLUSION: Bedside fetal magnetocardiography revealed the exact diagnosis of the long QT syndrome in a period of the gestation when the fetus was electrically isolated by the vernix caseosa that hinders electrocardiography. To patients at risk of fetal cardiac abnormalities, magnetocardiography can be offered as a non-invasive diagnostic bedside procedure. The diagnosis should trigger closer surveillance and delivery in a perinatal center.     

Moving with the beat: changing fetal monitoring practices in low-risk labour

In current practice electronic fetal monitoring is used extensively to assess fetal well-being in normal or low-risk labour. Within this clinical context there are a number of issues concerning the comparative benefits or problems of this practice when compared with intermittent auscultation. The purpose of this study was to explore factors influencing current practice by systematically investigating and describing changes in practice, encompassing the period of time prior to and following, the introduction of electronic fetal monitoring, and up to the present day. To do this text from the 13 editions of Margaret Myles's 'Text Book for Midwives', was subjected to a qualitative content analysis. The data revealed five distinct patterns of practice, each correlating loosely to a calendar decade and each reflecting different norms for childbirth and midwifery practice. The findings suggest that there is a significant shift in the skills and context associated with fetal monitoring, changes that require reflection and debate.     

The evaporation test for detecting rupture of the fetal membranes

A method for detecting rupture of the fetal membranes, first described by Iannetta in 1984, has been tested. It is based on the heating of endocervical material on a glass slide to evaporate water, thus leaving a white residue if amniotic fluid is present and a brown residue if it is not. The method is simple, quick and inexpensive. The study showed the method to be reliable if the result is positive, but also to produce some false-negative results. Interpretation may in some cases be open to observer bias unless clearly positive. Positive results were seen as early as in week 26. This method may prove to be a valuable addition to other tests for detecting rupture of the fetal membranes.     

Assessment of fetal heart rate and fetal movements in detecting oxygen deprivation in-utero

This article reviews the physiological principles underlying the application of assessment of fetal movements and fetal heart rate (FHR) in detecting fetal hypoxia. Studies in both fetal sheep and healthy human fetuses are discussed including those which have demonstrated the importance of appreciating the existence of rest-activity cycles under normal physiological conditions. The role of adenosine in mediating the hypoxic inhibition of fetal breathing movements (FBMs) is reviewed as is the previously unrecognized importance of fetal gasping as a possible new measure of fetal hypoxia.     

Focus on the beat: current fetal monitoring practice in low risk labour

Assessing fetal heart and thus fetal wellbeing during labour and childbirth is an important if contentious, clinical practice. There is debate and concern about optimal methods of fetal monitoring during low risk childbirth. This paper reports on the findings of a qualitative study that investigated current midwives' practices. Data from focus groups conducted with midwives practising in Queensland was subject to a qualitative content analysis. While the ideal method of monitoring the fetal heart in low-risk labour is intermittent auscultation this analysis highlights not only the range of methods but also the rationales, contexts and factors motivating and influencing midwives' practice choices. In the current complex care environment midwives face a range of challenges to practice that facilitate the provision of consistent woman-centered care.     

Alteration in the low-frequency domain in power spectral analysis of fetal heart beat fluctuations

OBJECTIVE: Spectral analysis was conducted on fetal heart rate fluctuations for the purpose of investigating the change in gestational age and examining the usefulness as a method of estimating fetal blood gas. STUDY DESIGN: Five hundred and twenty-nine pregnant women with a single normal fetus and 26 women with intrauterine growth restriction (IUGR) were studied during the 20th to 38th gestational weeks. In cases of IUGR, fetal blood gas levels were evaluated with percutaneous umbilical blood sampling. A time series of fetal heart rate fluctuation was obtained with a 1. 15-MHz ultrasonic transducer, and power spectral analysis of 200 consecutive stable beats was performed with an autoregression method. Integrated areas of 0.025-0.125 cycles/beat were defined as low-frequency areas (LFAs) and were examined in normal fetuses. In addition, the relation between LFA and fetal blood gas values was studied. RESULTS: As pregnancy progressed, LFA increased with a cubic regression equation (Y = 6.484 - 0.764X + 0.029X2 - 0.00034X3). The correlation coefficient was 0.625 (p < 0.05). In the cases of IUGR, DeltaLFA was highly correlated with DeltapO2 and DeltapH (correlation coefficient, 0.650 and 0.618, respectively). CONCLUSIONS: Measurement of LFA provides insight into the development of fetal autonomic function and also may serve as a quantitative index of fetal well-being in mid-pregnancy.     

Prenatal fetal sex diagnosis by detecting amelogenin gene in maternal plasma

OBJECTIVES: To provide a new, reliable noninvasive method for fetal sex determination. METHODS: Fetal sex was detected in 32 early pregnant women by identifying the amelogenin gene in maternal plasma using nested PCR analysis. First, the 122/128 bp of X-Y homologous region containing 6 bp deletions in the intron 3 of amelogenin gene in X chromosome was amplified, and then the nested PCR was carried out, whose 3' end of the upstream primer is just located in the deletion region. The fetus was male or female, depending on whether it had the 89-bp nested PCR product or not. RESULTS: The 89 bp of nested PCR product was detected in 19 plasma samples obtained from pregnant women, deducing they bear the male fetus and the remaining pregnant women bear female. When compared with the birth outcome, two samples were pseudo-positive. The coincidence was 93.8%. This method had high sensitivity that even trace amount of target fetal DNA (10 pg) could be detected. CONCLUSIONS: This conventional nested PCR analysis of amelogenin gene promises to be a reliable method for noninvasive fetal sex determination at early pregnancy using maternal plasma DNA.     

Diagnostic value of cervical fetal fibronectin in detecting extrauterine pregnancy.

OBJECTIVE: To determine whether fetal fibronectin (FFN) might serve as a marker to distinguish intrauterine versus extrauterine pregnancy. DESIGN: Prospective cohort study. SETTING: Academic research center. PATIENT(S): Cervicovaginal FFN samples were obtained from 46 women who were at high risk for or presented with signs and/or symptoms of extrauterine pregnancy. INTERVENTION(S): Samples of blood were analyzed for FFN with use of an enzyme-linked immunoabsorbent assay (ELISA). MAIN OUTCOME MEASURE(S): Fetal fibronectin level. RESULT(S): The rate of extrauterine pregnancy in our study was 26.1%, with 12 extrauterine and 34 intrauterine pregnancies identified by ultrasonography or at time of surgery. Seventeen samples had FFN levels of > 50 ng/mL and were considered positive (range, 0-1,000 ng/mL). Positive FFN levels were observed in 41.7% (5 of 12) of women with extrauterine pregnancies versus 35.3%) (12 of 34) of women with intrauterine pregnancies. The sensitivity, specificity, and positive and negative predictive values for extrauterine pregnancy were 41.7%, 64.7%, 29.4%, and 75.9%, respectively. CONCLUSION(S): The use of FFN does not appear to alter significantly the likelihood of identifying extrauterine pregnancy over current laboratory or ultrasonographic methods.     

Fetal arrhythmias case series: Experiences from a fetal screening center in Taiwan

ObjectiveFetal arrhythmias are common and in rare cases can be associated with severe mortality and morbidity. Most existing articles are focused on classification of fetal arrhythmias in referral centers. Our main objective was to analyze types, clinical characteristics, and outcomes for arrhythmia cases in general practice.Case reportWe retrospectively reviewed a case series of fetal arrhythmias in a fetal medicine clinic between September 2017 and August 2021.Fetal arrhythmias in our sample presented byEctopies (86%, n = 57), bradyarrhythmias (11%, n = 7), and tachyarrhythmias (3%, n = 2). One tachyarrhythmia case was associated with Ebstein's anomaly. Two cases of second-degree AV block received transplacental fluorinated steroid therapy with recovery of fetal cardiac rhythm in later gestation. One case of complete AV block developed hydrops fetalis.ConclusionDetection and careful stratification of fetal arrhythmias in obstetric screening is crucial. While most arrhythmias are benign and self-limited, some require prompt referral and timely intervention.