The impact of intrauterine treatment on fetal tachycardia: a nationwide survey in Japan

Advances and challenges of prenatal interventions for fetal tachyarrhythmias

It is estimated that 1%-2% of pregnancies are complicated by fetal arrhythmias, with most arrhythmias considered benign and not requiring further treatment or intervention. However, persistent tachyarrhythmias can lead to fetal heart failure, preterm birth, stillbirth, and increased risks during the perinatal period. Therefore, timely treatment during pregnancy is often necessary. Currently, prenatal treatment for fetal tachyarrhythmias (FTs) is primarily drug based, aiming to restore normal fetal heart rate, prevent or reverse fetal heart failure, and avoid adverse outcomes such as preterm birth and stillbirth. Despite decades of clinical experience, the lack of prospective, multicenter randomized clinical trials on the safety and efficacy of drugs means that there is still no universally accepted prenatal treatment regimen for FTs, and treatment relies on series of observational studies or clinical cases. Moreover, all drug treatments carry potential risks to the mother, fetus, and pregnancy, hence the need for more clinical diagnostic and therapeutic experience to provide more clinical evidence for prenatal treatment of FTs.

Outcome of Fetal Dysrhythmias with and without Extracardiac Anomalies

Fetal dysrhythmias are common abnormalities, which can be categorized into three types: rhythm irregularities, tachyarrhythmias, and bradyarrhythmias. Fetal arrhythmias, especially in high-risk pregnancies, require special monitoring and treatment. The aim of this study was to assess the stillbirth and early and late neonatal mortality rates for pregnancies complicated by fetal dysrhythmias from one single tertiary referral center from 2000 to 2022. Of the 1018 fetuses with congenital heart disease, 157 (15.42%) were evaluated in this analysis. Seventy-four (46.7%) fetuses had bradyarrhythmias, 51 (32.5%) tachyarrhythmias, and 32 (20.4%) had rhythm irregularities. Additional structural heart defects were detected in 40 (25.3%) fetuses and extracardiac anomalies in 29 (18.4%) fetuses. Thirteen (8.2%) families opted for termination of the pregnancy. Eleven (7.6%), out of 144 continued pregnancies ended in spontaneous intrauterine fetal death (IUFD). Neonatal death was observed in nine cases (5.7%), whereas three (1.9%) died within the first 7 days of life. Although most intrauterine fetal deaths occurred in pregnancies with fetal bradyarrhythmia, neonatal death was observed more often in fetuses with tachyarrhythmia (8.5%). The presence of extracardiac anomalies, congenital heart disease (CHD), and Ro-antibodies are predictive factors for the occurrence of IUFD. Rhythm irregularities without any other risk factor do not present higher risks of adverse perinatal outcome.

Frequency-Based Maternal Electrocardiogram Attenuation for Fetal Electrocardiogram Analysis

Fetal electrocardiogram (ECG) waveform analysis along with cardiac time intervals (CTIs) measurements are critical for the management of high-risk pregnancies. Currently, there is no system that can consistently and accurately measure fetal ECG. In this work, we present a new automatic approach to attenuate the maternal ECG in the frequency domain and enhance it with measurable CTIs. First, the coherent components between the maternal ECG and abdominal ECG were identified and subtracted from the latter in the frequency domain. The residual was then converted into the time domain using the inverse Fourier transform to yield the fetal ECG. This process was improved by averaging multiple beats. Two fetal cardiologists, blinded to the method, assessed the quality of fetal ECG based on a grading system and measured the CTIs. We evaluated the fetal ECG quality of our method and time-based methods using one synthetic dataset, one human dataset available in the public domain, and 37 clinical datasets. Among the 37 datasets analyzed, the mean average (± standard deviation) grade was 3.49 ± 1.22 for our method vs. 2.64 ± 1.26 for adaptive interference cancellation (p-value < 0.001), thus showing the frequency-based fetal ECG extraction was the superior method, as assessed from our clinicians' perspectives. This method has the potential for use in clinical settings.

Cardiac arrhythmias in pregnant women: need for mother and offspring protection

Cardiac arrhythmias are the most common cardiac complication reported in pregnant women with and without structural heart disease (SHD); they are more frequent among women with SHD, such as cardiomyopathy and congenital heart disease (CHD). While older studies had indicated supraventricular tachycardia as the most common tachyarrhythmia in pregnancy, more recent data indicate an increase in the frequency of arrhythmias, with atrial fibrillation (AF) emerging as the most frequent arrhythmia in pregnancy, attributed to an increase in maternal age, cardiovascular risk factors and CHD in pregnancy. Importantly, the presence of any tachyarrhythmia during pregnancy may be associated with adverse maternal and fetal outcomes, including death. Thus, both the mother and the offspring need to be protected from such consequences. The use of antiarrhythmic drugs (AADs) depends on clinical presentation and on the presence of underlying SHD, which requires caution as it promotes pro-arrhythmia. In hemodynamically compromised women, electrical cardioversion is successful and safe to both mother and fetus. Use of beta-blockers appears quite safe; however, caution is advised when using other AADs, while no AAD should be used, if at all possible, during the first trimester when organogenesis takes place. Regarding the anticoagulation regimen in patients with AF, warfarin should be substituted with heparin during the first trimester, while direct oral anticoagulants are not indicated given the lack of data in pregnancy. Finally, for refractory arrhythmias, ablation and/or device implantation can be performed with current techniques in pregnant women, when needed, using minimal exposure to radiation. All these issues and relevant current guidelines are herein reviewed.

Antenatal Therapy for Fetal Supraventricular Tachyarrhythmias: Multicenter Trial

BACKGROUND

Standardized treatment of fetal tachyarrhythmia has not been established.

OBJECTIVES

This study sought to evaluate the safety and efficacy of protocol-defined transplacental treatment for fetal supraventricular tachycardia (SVT) and atrial flutter (AFL).

METHODS

In this multicenter, single-arm trial, protocol-defined transplacental treatment using digoxin, sotalol, and flecainide was performed for singleton pregnancies from 22 to <37 weeks of gestation with sustained fetal SVT or AFL ≥180 beats/min. The primary endpoint was resolution of fetal tachyarrhythmia. Secondary endpoints were fetal death, pre-term birth, and neonatal arrhythmia. Adverse events (AEs) were also assessed.

RESULTS

A total of 50 patients were enrolled at 15 institutions in Japan from 2010 to 2017; short ventriculoatrial (VA) SVT (n = 17), long VA SVT (n = 4), and AFL (n = 29). One patient with AFL was excluded because of withdrawal of consent. Fetal tachyarrhythmia resolved in 89.8% (44 of 49) of cases overall and in 75.0% (3 of 4) of cases of fetal hydrops. Pre-term births occurred in 20.4% (10 of 49) of patients. Maternal AEs were observed in 78.0% (39 of 50) of patients. Serious AEs occurred in 1 mother and 4 fetuses, thus resulting in discontinuation of protocol treatment in 4 patients. Two fetal deaths occurred, mainly caused by heart failure. Neonatal tachyarrhythmia was observed in 31.9% (15 of 47) of neonates within 2 weeks after birth.

CONCLUSIONS

Protocol-defined transplacental treatment for fetal SVT and AFL was effective and tolerable in 90% of patients. However, it should be kept in mind that serious AEs may take place in fetuses and that tachyarrhythmias may recur within the first 2 weeks after birth.

Fetal arrhythmias: prenatal evaluation and intrauterine therapeutics

Introduction

Fetal arrhythmias are a common phenomenon with rather complicated etiologies. Debates remain regarding prenatal diagnosis and treatment of fetal arrhythmias.

Methods

The literature reporting on prenatal diagnosis and treatment of fetal arrhythmias published in the recent two decades were retrieved, collected and analyzed.

Results

Both fetal magnetocardiogram and electrocardiogram provide information of cardiac time intervals, including the QRS and QT durations. M-mode ultrasound detects the AV and VA intervals, fetal heart rate, and AV conduction. By using Doppler ultrasound, simultaneous recording of the atrial and ventricular waves can be obtained. Benign fetal arrhythmias, including premature contractions and sinus tachycardia, do not need any treatment before and after birth. Sustained fetal arrhythmias that predispose to the occurrence of hydrops fetalis, cardiac dysfunction or eventual fetal demise require active treatments. Intrauterine therapy of fetal tachyarrhythmias has been carried out by the transplacental route. If maternal transplacental treatment fails, intraumbilical, intraperitoneal, or direct fetal intramuscular injection of antiarrhythmic agents can be attempted.

Conclusions

The outcomes of intrauterine therapy of fetal tachyarrhythmias depend on the types or etiology of fetal arrhythmias and fetal conditions. Most are curable to a transplacental treatment by the first-line antiarrhythmic agents. Fetal cardiac pacings are effective methods to restore sinus rhythm in drug-resistant or hemodynamically compromised cases. Immediate postnatal pacemaker implantation is warranted in refractory cases.

Plasma natriuretic peptide levels reflect the status of the heart failure in fetuses with arrhythmia

OBJECTIVES

To evaluate the significance of natriuretic peptide (NP) levels in fetal arrhythmia.

STUDY DESIGN

Cardiovascular profile (CVP) scores and umbilical vein (UV) NP levels at birth were compared by different fetal arrhythmia statuses.

RESULTS

Fetal tachyarrhythmia (n = 22), bradyarrhythmia (n = 12), extrasystole (n = 12) and controls (n = 127) were enrolled in this study. Fetal antiarrhythmic therapy was performed in fetuses with tachyarrhythmia (n = 18) and bradyarrhythmia (n = 5). Fetal arrhythmias were divided into three groups: group A (arrhythmia controlled at birth, n = 17), Group B (arrhythmia uncontrolled at birth, n = 9) and Group C (fetal therapy not indicated, n = 20). Group B had significantly lower CVP scores and higher NP levels than the other two groups and controls (p < .01). Groups A and C had significantly lower CVP scores than controls, but NP levels in Groups A and C showed no differences compared with controls.

CONCLUSIONS

UV NP concentrations reflect the severity of fetal arrhythmia and responses to fetal therapy.

Feasibility of Non-invasive Fetal Electrocardiographic Interval Measurement in the Outpatient Clinical Setting

Non-invasive fetal electrocardiography (ECG) is a promising method for evaluating fetal cardiac electrical activity. Despite advances in fetal ECG technology, its ability to provide reliable, interpretable results in a typical outpatient fetal cardiology setting remains unclear. We sought to determine the feasibility of measuring standard ECG intervals in an outpatient fetal cardiology practice using an abdominal fetal ECG device that employs blind source separation with reference, an innovative signal-processing technique for fetal ECG extraction. Women scheduled for clinically indicated outpatient fetal echocardiogram underwent 10 min of fetal ECG acquisition from the maternal abdomen using specialized gel electrodes. A bedside laptop computer performed fetal ECG extraction, allowing real-time visualization of fetal and maternal ECG signals. Offline post-processing of 1 min of recorded data yielded fetal P-wave duration, PR interval, QRS duration, RR interval, QT interval, and QTc. Fifty-five fetuses were studied with gestational age 18-37 weeks, including 13 with abnormal fetal echocardiogram findings and three sets of twins. Interpretable results were obtained in 91% of fetuses, including 85% during the vernix period and 100% of twin fetuses. PR interval and RR interval of 18-24 week gestation fetuses were significantly shorter than those with gestational age 25-31 and 32-37 weeks. Of the six fetuses with abnormal rhythms on fetal echocardiogram, fetal ECG tracing was interpretable in five and matched the rhythm noted on fetal echocardiogram. Abdominal fetal ECG acquisition is feasible for arrhythmia detection and ECG interval calculation in a routine clinical setting.

Maternal monitoring and safety considerations during antiarrhythmic treatment for fetal supraventricular tachycardia

Fetal tachycardia is a rare complication during pregnancy. After exclusion of maternal and fetal conditions that can result in a secondary fetal tachycardia, supraventricular tachycardia is the most common cause of a primary sustained fetal tachyarrhythmia. In cases of sustained fetal supraventricular tachycardia, maternal administration of digoxin, flecainide, sotalol, and more rarely amiodarone, is considered. As these medications have the potential to cause significant adverse effects, we sought to examine maternal safety during transplacental treatment of fetal supraventricular tachycardia. In this narrative review we summarize the literature addressing pharmacologic properties, monitoring, and adverse reactions associated with medications most commonly prescribed for transplacental therapy of fetal supraventricular tachycardia. We also describe maternal monitoring practices and adverse events currently reported in the literature. In light of our findings, we provide clinicians with a suggested maternal monitoring protocol aimed at optimizing safety.

Maternal biomarkers for fetal heart failure in fetuses with congenital heart defects or arrhythmias

BACKGROUND

Diagnosis of fetal heart failure depends primarily on fetal ultrasonography assessment. Our recent study demonstrated that plasma natriuretic peptide levels in umbilical cord blood were correlated with the severity of heart failure in fetuses with congenital heart defects or arrhythmias. However, percutaneous umbilical blood sampling is an invasive procedure, and therefore, less or noninvasive biomarkers reflecting fetal heart failure are required.

OBJECTIVE

The aim of this study was to investigate the possibility of whether maternal serum biomarkers can diagnose fetal heart failure in fetuses with congenital heart defects or arrhythmias.

STUDY DESIGN

This exploratory cross-sectional study was conducted at a tertiary pediatric cardiac center. A total of 50 singletons with fetal congenital heart defects or arrhythmias and 50 controls who were registered in the National Cerebral and Cardiovascular Center Biobank from 2013 to 2016 were included. Maternal serum samples obtained during the third trimester were analyzed for 2 hormones and 36 cytokines using the Bio-Plex Pro Human Cancer Biomarker panels 1 and 2. We comprehensively analyzed the association between maternal serum biomarkers and ultrasonography findings or fetal arrhythmia status. Fetal heart failure was defined as a cardiovascular profile score ≤7.

RESULTS

Of 37 fetuses with congenital heart defects, heart failure was found in 1 case of tricuspid valve dysplasia with moderate tricuspid regurgitation. Of 13 fetuses with arrhythmias, 5 had heart failure at 28-33 weeks of gestation. Maternal serum cytokine and hormone concentrations were compared between patients with and without fetal heart failure at 28-33 weeks of gestation (n = 6 and n = 61, respectively). Sixty-one fetuses without heart failure consisted of 10 with congenital heart defect, 6 with arrhythmia, and 45 controls. Maternal serum concentrations of tumor necrosis factor-α, interleukin-6, soluble Fas ligand, transforming growth factor-α, and vascular endothelial growth factor-D were significantly higher when fetuses had heart failure than when they did not (P < .05), whereas maternal serum concentrations of heparin-binding epidermal growth factor-like growth factor were significantly lower when fetuses had heart failure than when they did not (P < .05). Multivariate analysis showed that maternal serum concentrations of tumor necrosis factor-α, vascular endothelial growth factor-D, and heparin-binding epidermal growth factor-like growth factor were independently associated with fetal heart failure. The cutoff values were as follows: tumor necrosis factor-α, 68 pg/mL (sensitivity of 50.0%, specificity of 93.4%, positive likelihood ratio of 7.6, negative likelihood ratio of 0.5); vascular endothelial growth factor-D, 1156 pg/mL (sensitivity of 50.0%, specificity of 93.4%, positive likelihood ratio of 7.6, negative likelihood ratio of 0.5); and heparin-binding epidermal growth factor-like growth factor, 90 pg/mL (sensitivity of 83.3%, specificity of 83.6%, positive likelihood ratio of 5.1, negative likelihood ratio of 0.2). The combination of these 3 cytokines showed sensitivity of 100%, specificity of 80.3%, positive likelihood ratio of 5.1, and negative likelihood ratio of 0. In the absence of fetal heart failure, concentrations of all maternal serum cytokines and hormones were similar in cases of fetal congenital heart defects and controls, while maternal serum soluble CD40 ligand concentrations were increased only in fetal arrhythmias.

CONCLUSION

Maternal serum concentrations of tumor necrosis factor-α, vascular endothelial growth factor-D, and heparin-binding epidermal growth factor-like growth factor were associated with fetal heart failure.