Fetal supraventricular tachycardia complicated by hydrops fetalis: a role for direct fetal intramuscular therapy

Pharmacological Management of Cardiac Arrhythmias in the Fetal and Neonatal Periods: A Scientific Statement From the American Heart Association: Endorsed by the Pediatric & Congenital Electrophysiology Society (PACES)

Disorders of the cardiac rhythm may occur in both the fetus and neonate. Because of the immature myocardium, the hemodynamic consequences of either bradyarrhythmias or tachyarrhythmias may be far more significant than in mature physiological states. Treatment options are limited in the fetus and neonate because of limited vascular access, patient size, and the significant risk/benefit ratio of any intervention. In addition, exposure of the fetus or neonate to either persistent arrhythmias or antiarrhythmic medications may have yet-to-be-determined long-term developmental consequences. This scientific statement discusses the mechanism of arrhythmias, pharmacological treatment options, and distinct aspects of pharmacokinetics for the fetus and neonate. From the available current data, subjects of apparent consistency/consensus are presented, as well as future directions for research in terms of aspects of care for which evidence has not been established.

Refractory supraventricular fetal tachycardia as a cause of non-immune hydrops: management conundrum

Supraventricular tachyarrhythmia (SVT) is the most common form of fetal tachyarrhythmias. The presentation can vary from ill-defined, non-sustained episodes of tachyarrhythmia to frank non-immune hydrops. The standard of care is transplacental therapy by treating the mother with oral antiarrhythmic drugs, followed by direct fetal therapy in refractory cases. We report a case of primigravida in her late 20s, who presented at 28.1 weeks of gestation with fetal hydrops and SVT. She was initially managed with oral digoxin and flecainide, but due to worsening hydrops, risk of fetal demise and extreme prematurity, further management by direct fetal therapy was given in terms of intramuscular digoxin and intraperitoneal flecainide. Following which, the fetus had a favourable outcome. This case highlights the possible role of direct fetal therapy in refractory cases of SVT.

Intrauterine management and outcomes of persistent fetal atrial flutter: A case report

BACKGROUND

Fetal atrial flutter (AF), accounting for 30% of all fetal tachyarrhythmias, predominantly (over 80%) manifests as a 2:1 atrioventricular conduction. Swift referral and timely intervention become imperative in instances of severe persistent arrhythmia.

CASE PRESENTATION

We discuss the case of a 32-year-old multiparous Chinese woman, at 30+2 weeks of gestation, wherein an ultrasonographic examination revealed persistent fetal AF (atrial rate ranging from 219 to 445 beats/min and ventricular rate from 219 to 228 beats/min, with a 2:1 or 1:1 down transmission) and minor ascites. Despite the maternal ingestion of digoxin and sotalol, the fetal heart rhythm remained uncorrected. Following this, at 32+3 weeks of gestation, an intramuscular injection of cedilanid, guided by ultrasound, was administered to the fetus. Postoperatively, the fetal ventricular rate demonstrated a decline after 6 days, and the ascites resolved. Subsequently, at 33+3 weeks, a cesarean section was necessitated due to maternal intolerance to the medication, resulting in the delivery of the infant. Remarkably, the infant's cardiac rhythm spontaneously converted to sinus rhythm within 5 min of birth. A follow-up conducted 1 year postpartum revealed no recurrence of AF.

CONCLUSIONS

This case illustrates that in the event of transplacental drug treatment failure, intrauterine therapeutic intervention should be considered. Moreover, it highlights the encouraging prognosis associated with fetal AF, as the cardiac rhythm spontaneously reverted to sinus rhythm postbirth in this instance.

2023 HRS expert consensus statement on the management of arrhythmias during pregnancy

This international multidisciplinary expert consensus statement is intended to provide comprehensive guidance that can be referenced at the point of care to cardiac electrophysiologists, cardiologists, and other health care professionals, on the management of cardiac arrhythmias in pregnant patients and in fetuses. This document covers general concepts related to arrhythmias, including both brady- and tachyarrhythmias, in both the patient and the fetus during pregnancy. Recommendations are provided for optimal approaches to diagnosis and evaluation of arrhythmias; selection of invasive and noninvasive options for treatment of arrhythmias; and disease- and patient-specific considerations when risk stratifying, diagnosing, and treating arrhythmias in pregnant patients and fetuses. Gaps in knowledge and new directions for future research are also identified.

Clinical characteristics and outcomes of atrial flutter in neonates

BACKGROUND

Atrial flutter is an uncommon arrhythmia that can cause severe morbidity, including heart failure and even death in refractory cases. This study investigated the clinical characteristics, treatment, and long-term outcomes of patients with neonatal atrial flutter and its association with heart failure.

METHODS

We retrospectively reviewed atrial flutter cases observed in our center between 1999 and 2021 and analyzed the clinical characteristics, treatment, and recurrence according to the presence of heart failure.

RESULTS

The study comprised 15 patients with atrial flutter, with median bodyweight and gestational age of 2.7 kg, 37+4 weeks, respectively. Twelve patients were diagnosed with atrial flutter on the first day of life. The median atrial and ventricular rates were 440/min, 220/min, respectively. Four patients exhibited congestive heart failure. Episodic recurrence was noted in five patients and occurred at a higher rate in patients with congestive heart failure (p = 0.004). Antiarrhythmic drugs for maintenance treatment were administered more often in patients with heart failure (p = 0.011). Initial treatment included direct current cardioversion (n = 9), digoxin (n = 4), and observation (n = 2). Four patients treated with cardioversion experienced recurrence during the neonatal period, and none of those treated with digoxin experienced recurrence. The median follow-up duration was 7 years, during which no atrial flutter recurrence was evident.

CONCLUSION

Neonates with congestive heart failure had a higher recurrence of atrial flutter. Direct current cardioversion is the most reliable treatment for neonatal atrial flutter, whereas digoxin may be a viable treatment option in refractory and recurrent cases.

Care of the Fetus With Congenital Cardiovascular Disease: From Diagnosis to Delivery

BACKGROUND

The majority of congenital cardiovascular disease including structural cardiac defects, abnormalities in cardiac function, and rhythm disturbances can be identified prenatally using screening obstetrical ultrasound with referral for fetal echocardiogram when indicated.

METHODS

Diagnosis of congenital heart disease in the fetus should prompt assessment for extracardiac abnormalities and associated genetic abnormalities once maternal consent is obtained. Pediatric cardiologists, in conjunction with maternal-fetal medicine, neonatology, and cardiothoracic surgery subspecialists, should counsel families about the details of the congenital heart defect as well as prenatal and postnatal management.

RESULTS

Prenatal diagnosis often leads to increased maternal depression and anxiety; however, it decreases morbidity and mortality for many congenital heart defects by allowing clinicians the opportunity to optimize prenatal care and plan delivery based on the specific lesion. Changes in prenatal care can include more frequent assessments through the remainder of the pregnancy, maternal medication administration, or, in selected cases, in utero cardiac catheter intervention or surgical procedures to optimize postnatal outcomes. Delivery planning may include changing the location, timing or mode of delivery to ensure that the neonate is delivered in the most appropriate hospital setting with the required level of hospital staff for immediate postnatal stabilization.

CONCLUSIONS

Based on the specific congenital heart defect, prenatal echocardiogram assessment in late gestation can often aid in predicting the severity of postnatal instability and guide the medical or interventional level of care needed for immediate postnatal intervention to optimize the transition to postnatal circulation.

Fetal Arrhythmia Diagnosis and Pharmacologic Management

One of the most successful achievements of fetal intervention is the pharmacologic management of fetal arrhythmias. This management usually takes place during the second or third trimester. While most arrhythmias in the fetus are benign, both tachy‐ and bradyarrhythmias can lead to fetal hydrops or cardiac dysfunction and require treatment under certain conditions. This review will highlight precise diagnosis by fetal echocardiography and magnetocardiography, the 2 primary means of diagnosing fetuses with arrhythmia. Additionally, transient or hidden arrhythmias such as bundle branch block, QT prolongation, and torsades de pointes, which can lead to cardiomyopathy and sudden unexplained death in the fetus, may also need pharmacologic treatment. The review will address the types of drug therapies; current knowledge of drug usage, efficacy, and precautions; and the transition to neonatal treatments when indicated. Finally, we will highlight new assessments, including the role of the nurse in the care of fetal arrhythmias. The prognosis for the human fetus with arrhythmias continues to improve as we expand our ability to provide intensive care unit–like monitoring, to better understand drug treatments, to optimize subsequent pregnancy monitoring, to effectively predict timing for delivery, and to follow up these conditions into the neonatal period and into childhood. Coordinated initiatives that facilitate clinical fetal research are needed to address gaps in knowledge and to facilitate fetal drug and device development.

Fetal Intervention for Refractory Supraventricular Tachycardia Complicated by Hydrops Fetalis

Introduction. Few reports have shown promising treatments for refractory fetal tachycardia. Data are limited regarding optimal treatment, route of treatment, and medication dosages. Over 90% of cases of fetal tachycardia can be attributed to supraventricular tachycardia (SVT). The first-line treatment of fetal SVT is transplacental digoxin. Case Presentation. We present the management of a patient with fetal tachyarrhythmia diagnosed at 24 weeks and offer a unique approach for treatment. Fetal intramuscular injection of 72.3 mcg of digoxin allowed for resolution of SVT and sustained normal sinus rhythm. Further assessment in the third trimester showed persistent hydrops in the setting of mirror (Ballantyne's) syndrome resulting in delivery. Discussion/Conclusion. Our observations suggest that a one-time injection of digoxin allows for complete resolution of SVT. Utilizing an invasive approach for management of SVT that is resistant to traditional treatment modalities appears to both be therapeutic and decrease maternal adverse effects associated with more toxic effects of other transplacental medications.

Fetal Tachyarrhythmia Management from Digoxin to Amiodarone-A Review

Sustained fetal tachycardias are rare but represent a high risk of mortality and morbidity. Consensus has yet to be found regarding their optimal management. The aim of this narrative review is to summarize the data available in the current literature regarding the efficacy and safety of medications used in the management of intrauterine tachyarrhythmias and to provide possible treatment protocols. In this review, we would like to emphasize the importance of a thorough evaluation of both the fetus and the mother, prior to transplacental antiarrhythmic drug initiation. Factors such as the hemodynamic status of the fetus, possible mechanisms of fetal arrhythmia, and concomitant maternal conditions are of primordial importance. As a possible treatment protocol, we would like to recommend the following: due to the risk of sustained supraventricular tachycardia (SVT), fetuses with frequent premature atrial beats should be evaluated more frequently by echocardiography. A careful hemodynamic evaluation of a fetus with tachycardia is primordial in forestalling the appearance of hydrops. In the case of atrial flutter (AFL), sotalol therapy could represent a first choice, whereas when dealing with SVT patients, flecainide should be considered, especially for hydropic patients. These data require consolidation through larger scale, non-randomized studies and should be handled with caution.

Women-specific routes of administration for drugs: A critical overview

The woman's body presents a number of unique anatomical features that can constitute valuable routes for the administration of drugs, either for local or systemic action. These are associated with genitalia (vaginal, endocervical, intrauterine, intrafallopian and intraovarian routes), changes occurring during pregnancy (extra-amniotic, intra-amniotic and intraplacental routes) and the female breast (breast intraductal route). While the vaginal administration of drug products is common, other routes have limited clinical application and are fairly unknown even for scientists involved in drug delivery science. Understanding the possibilities and limitations of women-specific routes is of key importance for the development of new preventative, diagnostic and therapeutic strategies that will ultimately contribute to the advancement of women's health. This article provides an overview on women-specific routes for the administration of drugs, focusing on aspects such as biological features pertaining to drug delivery, relevance in current clinical practice, available drug dosage forms/delivery systems and administration techniques, as well as recent trends in the field.

The potentially protective role of ATP-binding cassette transporters in preeclampsia via Nrf2

OBJECTIVE

Preeclampsia (PE) is a severe placental syndrome that likely results from placental oxidative stress and inflammation, and can lead to maternal hypertension and premature delivery. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activates several genes involved in antioxidant defense in the placentae, along with the ATP-binding cassette (ABC) transporters which regulate substrate flow between maternal and fetal circulation. Although several ABC transporters are down-regulated in PE, their exact mechanistic role is poorly understood. METHODS＆ RESULTS: In this study, we compared the levels of major ABC transporters and NRF2 in placentae of healthy full-term pregnant women and those with early and term onset PE. We found a significant decrease in the levels of Nrf2 and several ABC transporters in the placentae of early onset compared to term onset PE. In addition, women with term onset PE showed improved post-partum parameters (lower blood pressure, and greater placental and neonatal weights) compared to those with early onset PE. Mechanistically, Nrf2 knockdown/knockout downregulated the genes for ABC transporters and antioxidant enzymes, and upregulated pro-inflammatory factors, whereas Nrf2 upregulation had the opposite effects.

CONCLUSIONS

Nrf2 protects the placenta against PE by activating the ABC transporter-mediated efflux, indicating a novel target in PE therapy.

Fetal Arrhythmias: Genetic Background and Clinical Implications

Fetal arrhythmias are a common phenomenon of pregnancies. However, debates remain with regard to the etiologies and early treatment of choices for severe fetal arrhythmias. The gene regulatory networks govern cardiac conduction system development to produce distinct nodal and fast conduction phenotypes. The slow conduction properties of nodes that display automaticity are determined by the cardiac ion channel genes, whereas the fast conduction properties are regulated by the transcription factors. Mutations of genes specific for the developmental processes and/or functional status of cardiac conduction system including ion channel promoter (minK-lacZ), GATA family of zinc finger proteins (GATA4), the homeodomain transcription factor (Nkx2.5), the homeodomain-only protein (Hop) and the T-box transcription factors (Tbx2, Tbx3 and Tbx5), hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) and connexins, may cause fetal arrhythmias. It is expected that development of investigational antiarrhythmic agents based on genetic researches on cardiac conduction system, and clinical application of percutaneously implantable fetal pacemaker for the treatment of fetal arrhythmias would come to true.

Fetal dysrhythmias

Fetal dysrhythmias are common abnormalities, usually manifesting as irregular rhythms. Although most irregularities are benign and caused by isolated atrial ectopics, in a few cases, rhythm irregularity may indicate partial atrioventricular block, which has different etiological and prognostic implications. We provide a flowchart for the initial management of irregular rhythm to help select cases requiring urgent specialist referral. Tachycardias and bradycardias are less frequent, can lead to hemodynamic compromise, and may require in utero therapy. Pharmacological treatment of tachycardia depends on the type (supraventricular tachycardia or atrial flutter) and presence of hydrops, with digoxin, flecainide, and sotalol being commonly used. An ongoing randomized trial may best inform about their efficacy. Bradycardia due to blocked bigeminy normally resolves spontaneously, but if it is due to established complete heart block, there is no effective treatment. Ongoing research suggests hydroxychloroquine may reduce the risk of autoimmune atrioventricular block. Sinus bradycardia (rate <3rd centile) may be a prenatal marker for long-QT syndrome.

Fetal arrhythmias: Surveillance and management

Fetal arrhythmias warrant sophisticated surveillance and management, especially for the high-risk pregnancies. Clinically, fetal arrhythmias can be categorized into 3 types: premature contractions, tachyarrhythmias, and bradyarrhythmias. Fetal arrhythmias include electrocardiography, cardiotocography, echocardiography and magnetocardiography. Oxygen saturation monitoring can be an effective way of fetal surveillance for congenital complete AV block or SVT during labor. Genetic surveillance of fetal arrhythmias may facilitate the understanding of the mechanisms of the arrhythmias and provide theoretical basis for diagnosis and treatment. For fetal benign arrhythmias, usually no treatment but a close follow-up is need, while persistant fetal arrhythmias with congestive heart dysfunction or hydrops fetalis, intrauterine or postnatal treatments are required. The prognoses of fetal arrhythmias depend on the type and severity of fetal arrhythmias and the associated fetal conditions. Responses of fetal arrhythmias to individual treatments and clinical schemes are heterogeneous, and the prognoses are poor particularly under such circumstances.

Successful in utero transesophageal pacing for severe drug-resistant tachyarrhythmia

Sustained fetal tachyarrhythmia can evolve into a life-threatening condition in 40% of cases when hydrops develops, with a 27% risk of perinatal death. Several antiarrhythmic drugs can be given solely or in combination to the mother to achieve therapeutic transplacental concentrations. Therapeutic failure could lead to progressive cardiac insufficiency and restrict therapeutic options to either elective delivery or direct fetal administration of antiarrhythmic drugs, which may increase the risk of death. We report for the first time successful fetal transesophageal pacing to treat a hydropic fetus with drug-resistant tachyarrhythmia.

Review Paper. Transplacental Digoxin Treatment In Prenatal Cardiac Problems In Singleton Pregnancies - Meta Analysis (Based On Literature: 1992–2015)

Based on fourteen case reports from various centres from 1992-2015 and three original studies in 2006-2011, 122 fetuses were subjected to analysis. In these reports, transplacental digoxin treatment was administered to different cardiac anomalies such as SVT , Ebstein’s anomaly, critical AS , absent pulmonary valve syndrome, complete heart block, in foetuses with aneurysm/diverticulum of LV, in tricuspid atresia or dysplasia, rhabdomyoma, pulmonary atresia, HLHS with fibroelastosis, in TTTS and in extracardiac anomalies such as atriovenous malformation or sacrococcygeal teratoma. There was no statistical difference to suggest (Chi-square test) that digoxin was more efficient to control fetal arrhythmias than fetal congestive heart failure in nonarrhythmic patients.

Conclusions: Foetal cardiac insufficiency may appear due to different reasons (in normal heart anatomy or in heart defects, in normal sinus rhythm or due to foetal arrhythmias: tachycardias or severe bradycardia) and may be a cause of intrauterine demise. So far, we do not have strong evidence that digoxin treatment may prevent foetal death or prematurity. More research is needed to ascertain if the prolonging of pregnancy resulted from digoxin treatment or if improvement in foetal circulatory insufficiency was influenced by spontaneous regression of foetal cardiac symptoms.

Fetal Atrial Flutter and Hydrops Successfully Treated with Transplacental and Direct Fetal Therapy

The hydropic fetus with atrial flutter has high risk of fetal demise. In utero treatment is not as successful as SVT with 1:1 conduction. Even after conversion to sinus rhythm, close follow-up of the pregnancy is required for several reasons..

Case Report:

A 25 year old primigravida, at 26 wks of gestation had a fetal ultrasound which showed a tachycardic hydropic fetus with AFI 49. The rhythm was atrial flutter: AR 400 bpm and VR 200 bpm. The heart was structurally normal. Transplacental antiarrhythmic treatment with sotalol was started and 24 hours later, the fetus was still primarily in flutter with rare episodes of sinus rhythm and frequent PAC. Sotalol was increased but the mother’s QTc increased to > 500 ms, so the sotalol dose was reduced. On day 4th direct i.m. of digoxin was given and fetus was in sinus rhythm. Pharmacotherapy was continued. On the 16th day of sinus rhythm (at 33 wks), a marked change in FHR variability was seen. An US revealed the fetus was in sinus rhythm with a normal FHR. Because of the decreased FHR variability, the fetus was delivered by CS and the cord pH was 7.19, Apgars 1, 9 and 9. The neonate received no antiarrhythmic medications. On day 6 of postnatal life, an AV re-entrant tachycardia (AVRT) developed and sinus rhythm was successfully restored with sotalol and digoxin. The infant was treated for 18 months with no episodes of SVT or atrial flutter.

Foetal supraventricular tachycardia with hydrops fetalis: a role for direct intraperitoneal amiodarone

INTRODUCTION

Persistent foetal tachyarrythmias complicated by hydrops fetalis carry a poor prognosis, with foetal death reported in excess of a quarter despite treatment. We present our experience with direct intraperitoneal amiodarone administration in eight hydropic foetuses with resistant supraventricular tachycardia.

METHODS

Amiodarone was injected slowly into foetal peritoneal cavity under ultrasound guidance. All mothers were loaded with oral amiodarone before the procedure and maintained on it. The procedure was repeated guided by foetal rhythm.

RESULT

All eight cases had severe hydrops with a median foetal heart rate of 255 bpm (range 240-300 bpm), and the median gestational age was 27+1 weeks (range 21-33+3 weeks) at presentation. In six cases, the average time for supraventricular tachycardia to revert to sinus rhythm from the first procedure was 11.5 days. In one case, intravascular injection of amiodarone into the umbilical vein was performed before intraperitoneal injection, which resulted in conversion to sinus rhythm sustained until delivery. In the last case, supraventricular tachycardia and severe hydrops persisted and the baby was delivered 5 days later at 34 weeks' gestation. Hydrops resolved in five foetuses with a mean resolution time of 28.4 days. The mean gestational age at delivery was 34+5 days and seven of eight cases survived beyond the neonatal period with good postnatal outcomes.

CONCLUSION

Intraperitoneal administration of amiodarone is a relatively simple and effective strategy in refractory supraventricular tachycardia complicated by severe hydrops. The intraperitoneal route assures delivery of the drug to the severely hydropic foetus and enables a bolus dose to be delivered for sustained absorption.

Diagnosis and treatment of fetal arrhythmia

AIMS

Detection and careful stratification of fetal heart rate (FHR) is extremely important in all pregnancies. The most lethal cardiac rhythm disturbances occur during apparently normal pregnancies where FHR and rhythm are regular and within normal or low-normal ranges. These hidden depolarization and repolarization abnormalities, associated with genetic ion channelopathies cannot be detected by echocardiography, and may be responsible for up to 10% of unexplained fetal demise, prompting a need for newer and better fetal diagnostic techniques. Other manifest fetal arrhythmias such as premature beats, tachycardia, and bradycardia are commonly recognized.

METHODS

Heart rhythm diagnosis in obstetrical practice is usually made by M-mode and pulsed Doppler fetal echocardiography, but not all fetal cardiac time intervals are captured by echocardiographic methods.

RESULTS AND CONCLUSIONS

This article reviews different types of fetal arrhythmias, their presentation and treatment strategies, and gives an overview of the present and future diagnostic techniques.

Diagnosis and treatment of fetal cardiac disease: a scientific statement from the American Heart Association

BACKGROUND

The goal of this statement is to review available literature and to put forth a scientific statement on the current practice of fetal cardiac medicine, including the diagnosis and management of fetal cardiovascular disease.

METHODS AND RESULTS

A writing group appointed by the American Heart Association reviewed the available literature pertaining to topics relevant to fetal cardiac medicine, including the diagnosis of congenital heart disease and arrhythmias, assessment of cardiac function and the cardiovascular system, and available treatment options. The American College of Cardiology/American Heart Association classification of recommendations and level of evidence for practice guidelines were applied to the current practice of fetal cardiac medicine. Recommendations relating to the specifics of fetal diagnosis, including the timing of referral for study, indications for referral, and experience suggested for performance and interpretation of studies, are presented. The components of a fetal echocardiogram are described in detail, including descriptions of the assessment of cardiac anatomy, cardiac function, and rhythm. Complementary modalities for fetal cardiac assessment are reviewed, including the use of advanced ultrasound techniques, fetal magnetic resonance imaging, and fetal magnetocardiography and electrocardiography for rhythm assessment. Models for parental counseling and a discussion of parental stress and depression assessments are reviewed. Available fetal therapies, including medical management for arrhythmias or heart failure and closed or open intervention for diseases affecting the cardiovascular system such as twin-twin transfusion syndrome, lung masses, and vascular tumors, are highlighted. Catheter-based intervention strategies to prevent the progression of disease in utero are also discussed. Recommendations for delivery planning strategies for fetuses with congenital heart disease including models based on classification of disease severity and delivery room treatment will be highlighted. Outcome assessment is reviewed to show the benefit of prenatal diagnosis and management as they affect outcome for babies with congenital heart disease.

CONCLUSIONS

Fetal cardiac medicine has evolved considerably over the past 2 decades, predominantly in response to advances in imaging technology and innovations in therapies. The diagnosis of cardiac disease in the fetus is mostly made with ultrasound; however, new technologies, including 3- and 4-dimensional echocardiography, magnetic resonance imaging, and fetal electrocardiography and magnetocardiography, are available. Medical and interventional treatments for select diseases and strategies for delivery room care enable stabilization of high-risk fetuses and contribute to improved outcomes. This statement highlights what is currently known and recommended on the basis of evidence and experience in the rapidly advancing and highly specialized field of fetal cardiac care.

Prenatal pharmacotherapy for fetal anomalies: a 2011 update

Fetal therapy can be defined as any prenatal treatment administered to the mother with the primary indication to improve perinatal or long-term outcomes for the fetus or newborn. This review provides an update of the pharmacological therapies that are solely directed at the fetus with anomalies and outlines a future transcriptomic approach. Fetal anomalies targeted with prenatal pharmacotherapy are a heterogeneous group of structural, endocrine, and metabolic conditions, including congenital cystic adenomatoid malformation (CCAM), congenital adrenal hyperplasia, congenital heart block, fetal tachyarrhythmias, inborn errors of metabolism, fetal thyroid disorders, and polyhydramnios. To date, the majority of pharmacotherapies for fetal anomalies have been evaluated only in retrospective, uncontrolled studies. The way forward will be with an evidence-based approach to prenatal pharmacological interventions.

Fetal cardiac arrhythmia detection and in utero therapy

The human fetal heart develops arrhythmias and conduction disturbances in response to ischemia, inflammation, electrolyte disturbances, altered load states, structural defects, inherited genetic conditions, and many other causes. Yet sinus rhythm is present without altered rate or rhythm in some of the most serious electrophysiological diseases, which makes detection of diseases of the fetal conduction system challenging in the absence of magnetocardiographic or electrocardiographic recording techniques. Life-threatening changes in QRS or QT intervals can be completely unrecognized if heart rate is the only feature to be altered. For many fetal arrhythmias, echocardiography alone can assess important clinical parameters for diagnosis. Appropriate treatment of the fetus requires awareness of arrhythmia characteristics, mechanisms, and potential associations. Criteria to define fetal bradycardia specific to gestational age are now available and may allow detection of ion channelopathies, which are associated with fetal and neonatal bradycardia. Ectopic beats, once thought to be entirely benign, are now recognized to have important pathologic associations. Fetal tachyarrhythmias can now be defined precisely for mechanism-specific therapy and for subsequent monitoring of response. This article reviews the current and future diagnostic techniques and pharmacologic treatments for fetal arrhythmia.

Overview of fetal arrhythmias

PURPOSE OF REVIEW

Though fetal arrhythmias account for a small proportion of referrals to a fetal cardiologist, they may be associated with significant morbidity and mortality. The present review outlines the current literature with regard to the diagnosis and, in brief, some management strategies in fetal arrhythmias.

RECENT FINDINGS

Advances in echocardiography have resulted in significant improvements in our ability to elucidate the mechanism of arrhythmia at the bedside. At the same time, magnetocardiography is broadening our understanding of mechanisms of arrhythmia especially as it pertains to ventricular arrhythmias and congenital heart block. It provides a unique window to study electrical properties of the fetal heart, unlike what has been available to date. Recent reports of bedside use of fetal ECG make it a promising new technology. Fetal magnetocardiography is also developing. The underlying mechanisms resulting in immune-mediated complete heart block in a small subset of 'at-risk' fetuses is under investigation.

SUMMARY

There have been great strides in noninvasive diagnosis of fetal arrhythmias. However, we still need to improve our knowledge of the electromechanical properties of the fetal heart as well as the mechanisms of arrhythmia to further improve outcomes. Multiinstitutional collaborative studies are needed to help answer some of the questions regarding patient, drug selection and management algorithms.

Drug management of fetal tachyarrhythmias: are we ready for a systematic and evidence-based approach?

Fetal tachyarrhythmias are a life-threatening condition complicating a small proportion of normal pregnancies. Despite major advances in the (intrauterine) pharmacologic treatment of these arrhythmias over the last years major uncertainties remain. Among these are controversies in the choice of agents in relation to arrhythmia type, and timing and duration of treatment. Currently, no evidence-based approach to the management of fetal tachyarrhythmias is available. An international registry is proposed as an important step toward obtaining the necessary data to develop evidence-based management strategies.

Perinatal arrhythmias: diagnosis and management

The final common pathway to death in all of us is an arrhythmia, yet we still know far too little about the contribution of conduction abnormalities and arrhythmias to the compromised states of the human fetus. At no other time in the human life cycle is the human being at more risk of unexplained and unexpected death than during the prenatal period. The risk of sudden death from 20-40 weeks gestation is 6-12 deaths/1000 fetuses/year. This is equal to, and in some ethnic groups HIGHER than, the risk of death in the adult population with known coronary artery disease over the same time frame (6-12 deaths/1000 patients/year). Because only a small percentage of the United States population is pregnant each year, because fetal demise is not often acknowledged through public displays such as funerals, and finally because fetal death is culturally accepted to a much greater extent than it should be, this critically important area of women's healthcare has not had the technological advances that have been seen in adult cardiac intensive care and other areas of medicine. Fetal cardiac deaths may be preventable and the diseases that lead to these deaths are often treatable, especially if the sophistication of our modern ICU's could somehow be translated to the prenatal monitoring arena. This review article will outline recent advances in evaluating fetal electrophysiology, helping the perinatologist to better understand the nuances of fetal arrhythmias.

Outcome of fetal cardiac defects

PURPOSE OF REVIEW

The present review summarizes the prenatal and postnatal outcome of cardiac anomalies and sustained arrhythmias diagnosed during fetal life.

RECENT FINDINGS

The outcome of sustained fetal arrhythmias has improved with greater experience using Sotalol for atrial flutter, and digoxin and amiodarone for 1: 1 reciprocating tachycardia. The outcome of fetal conduction system disease secondary to maternal Sjögren's antibodies has noticeably improved with transplacental dexamethasone. The postnatal prognosis for atrioventricular block associated with left atrial isomerism, however, remains very bleak. Assessing the effect of prenatal diagnosis on the outcome of structural defects remains difficult because of the high number of extracardiac anomalies and chromosome defects in this group. Preoperative survival is improved, but postoperative mortality has not improved. One clear advantage of prenatal diagnosis is the selection of fetuses that may benefit from in-utero intervention to limit the progression of their disease or lessen its severity at birth.

SUMMARY

For the most part, postoperative mortality of structural cardiac defects is not significantly improved by prenatal diagnosis. In-utero management of tachyarrhythmias and conduction system disease has improved postnatal outcome, except for the fetus with atrioventricular block and left atrial isomerism.

Prenatal diagnosis of fetal arrhythmias

Life-threatening fetal arrhythmias are rare and warrant sophisticated specialty prenatal care, often provided by maternal-fetal medicine obstetricians, and pediatric and adult cardiologists. This medical field is in quick transition, and new methods of diagnosis and treatment of the fetus with arrhythmias are emerging. In this article, the mechanisms of arrhythmias are presented in light of recent progress in the new field of fetal electrophysiology. Treatments are reviewed with recommendations based on the small number of series of fetal tachycardia and fetal atrioventricular (AV) block drug treatment strategies published to date. Finally, a summary of areas of potential future research is provided.

Management of fetal tachyarrhythmias

Fetal tachyarrhythmias are an important cause of fetal morbidity and mortality. The majority of fetal tachyarrhythmias are due to atrioventricular reentrant type of supraventricular tachycardia and atrial flutter. Fetal echocardiography remains the main tool of diagnosing and discerning the mechanism of tachyarrhythmia. The goals of therapy for fetal arrhythmias are to restore sinus rhythm, resolve heart failure, and postpone delivery before term. Although there is no anonymity in the approach to the drug treatment of fetal tachycardia, digoxin is the most commonly employed first-line antiarrhythmic drug for supraventricular tachycardia. In digoxin nonresponders, flecainide ( digoxin) controls tachyarrhythmia with high conversion rate. A combination of digoxin and sotalol has proved effective therapy for atrial flutter, but the proarrhythmic side effect of sotalol on the fetus has been a concern. Amiodarone has emerged as a second-line treatment after digoxin failure in nonhydropic fetuses and the most effective treatment for drug-refractory fetal tachycardia accompanied by hydrops. Both the fetus and mother should be closely monitored for the response and adverse effect of the treatment. The antiarrhythmic treatment for supraventricular tachycardia should be continued after birth and during infancy due to the high incidence of postnatal recurrence.

Differential diagnosis and management of the fetus and newborn with an irregular or abnormal heart rate

This article separately discusses the differential diagnosis and management of irregular or abnormal heart rate in both the fetus and the newborn. Conditions covered include ectopic beats, tachyarrythmias,atrial flutter, bradyarrythmias, tachycardia, congenital atrioventricular block, long QT syndrome, and bradycardias,among others.

Nonimmune fetal ascites: a series of 79 cases

OBJECTIVE

The purpose of this study was to analyze the precision of ultrasonography in defining the cause and prognosis in fetal ascites.

STUDY DESIGN

We conducted a retrospective study of 79 cases of fetal ascites.

RESULTS

The mortality rate was 57% overall and ranged from 100% (7/7 cases) for metabolic storage disease to 0% (0/3 cases) in chylous ascites. Ascites before 24 weeks of gestation or combined with fetal hydrops indicates poor prognosis (respectively, 78.6% vs 45% mortality rate after 24 weeks; P<.01; and 77% vs 50.8% without hydrops; P<.02). Ascites was organic in 45 cases, infectious in 13 cases, idiopathic in 12 cases, and genetic in 9 cases. The cause was defined ultrasonographically in 28 of the 45 organic ascites and in 8 of the 25 isolated ascites. Urinary cause was the most frequent and the most successfully specified cause (14/15 cases).

CONCLUSION

Routine ultrasonography detects fetal ascites, but the cause is extremely variable and difficult to specify. When associated with fetal hydrops, the prognosis is poor.

Amiodarone Therapy for Drug-Refractory Fetal Tachycardia

Background— Fetal tachycardia complicated by ventricular dysfunction and hydrops fetalis carries a significant risk of morbidity and mortality. Transplacental digoxin is effective therapy in a small percentage, but there is no consensus with regard to antiarrhythmic treatment if digoxin fails. This study evaluates the safety, efficacy, and outcome of amiodarone therapy for digoxin-refractory fetal tachycardia with heart failure.

Methods and Results— Fetuses with incessant tachycardia and either hydrops fetalis (n=24) or ventricular dysfunction (n=2) for whom digoxin monotherapy and secondary antiarrhythmic agents (n=13) were not effective were treated transplacentally with a loading dose of oral amiodarone for 2 to 7 days, followed by daily maintenance therapy for <1 to 15 weeks. Digoxin therapy was continued throughout gestation. Newborns were studied by transesophageal pacing or ECG monitoring to determine the mechanism of tachycardia. Three fetuses were delivered urgently in tachycardia during amiodarone loading, and 3 required additional antiarrhythmic agents for sustained cardioversion. Amiodarone or amiodarone combinations converted 14 of 15 (93%) with reentrant supraventricular tachycardia, 2 of 2 with ventricular or junctional ectopic tachycardia, and 3 of 9 (33%) with atrial flutter. Amiodarone-related adverse effects were transient in 5 infants and 8 mothers. Mean gestational age at delivery was 37 weeks, with 100% survival.

Conclusions— Orally administered amiodarone is safe and effective treatment for drug-refractory fetal tachycardia, specifically reentrant supraventricular tachycardia, junctional ectopic, or ventricular tachycardia, even when accompanied by hydrops fetalis or ventricular dysfunction.

Drug treatment of fetal tachycardias

The pharmacological treatment of fetal tachycardia (FT) has been described in various publications. We present a study reviewing the necessity for treatment of FT, the regimens of drugs used in the last two decades and their mode of administration. The absence of reliable predictors of fetal hydrops (FH) has led most centers to initiate treatment as soon as the diagnosis of FT has been established, although a small minority advocate nonintervention. As the primary form of pharmacological intervention, oral maternal transplacental therapy is generally preferred. Digoxin is the most common drug used to treat FT; however, effectiveness remains a point of discussion. After digoxin, sotalol seems to be the most promising agent, specifically in atrial flutter and nonhydropic supraventricular tachycardia (SVT). Flecainide is a very effective drug in the treatment of fetal SVT, although concerns about possible pro-arrhythmic effects have limited its use. Amiodarone has been described favorably, but is frequently excluded due to its poor tolerability. Verapamil is contraindicated as it may increase mortality. Conclusions on other less frequently used drugs cannot be drawn. In severely hydropic fetuses and/or therapy-resistant FT, direct fetal therapy is sometimes initiated. To minimize the number of invasive procedures, fetal intramuscular or intraperitoneal injections that provide a more sustained release are preferred. Based on these data we propose a drug protocol of sotalol 160 mg twice daily orally, increased to a maximum of 480 mg daily. Whenever sinus rhythm is not achieved, the addition of digoxin 0.25 mg three times daily is recommended, increased to a maximum of 0.5 mg three times daily. Only in SVT complicated by FH, either maternal digoxin 1 to 2mg IV in 24 hours, and subsequently 0.5 to 1 mg/day IV, or flecainide 200 to 400 mg/day orally is proposed. Initiating direct fetal therapy may follow failure of transplacental therapy.

Flecainide in the intrauterine treatment of fetal supraventricular tachycardia

OBJECTIVES

To assess the efficacy of flecainide in the intrauterine treatment of fetal supraventricular tachycardia (SVT) with 1 : 1 atrioventricular conduction.

DESIGN

Twenty fetuses (21-35 weeks of gestation) with SVT ranging between 215 and 280 bpm were analyzed retrospectively. Fetuses received flecainide and digoxin as either first, second or third line therapy. Intracardiac blood flow, venous Doppler waveforms and cardiotocograms were evaluated before and after drug induced conversion to sinus rhythm.

RESULTS

After initiation of combined flecainide and digoxin therapy, the median time interval until final conversion to sinus rhythm was 5 days (range, 0-14 days). The majority of fetuses (n = 15; 75%) converted to sinus rhythm within 7 days of treatment, whereas the remaining five (25%) showed initial reduction of the heart rate to 160-215 bpm over several days, with restoration of a triphasic venous blood flow pattern before late conversion within 7-14 days after initiation of flecainide treatment. One of these fetuses showed a decrease in fetal heart rate to 160-190 bpm without conversion to sinus rhythm but with resolution of hydrops. All fetuses survived.

CONCLUSIONS

Flecainide is safe and highly effective in the intrauterine treatment of hydropic fetuses with supraventricular tachycardia. Conversion into sinus rhythm can be expected 72 h after initiation of therapy but may take up to 14 days. Therefore therapy should be continued beyond 72 h, especially when an initial decrease of fetal heart rate is observed which may represent an early therapeutic response.

Antiarrhythmic drugs in pregnancy

During pregnancy a number of rhythm disturbances can occur in both the mother and fetus; these may range from benign ectopy to life-threatening arrhythmias. With a clear understanding of the maternal hemodynamic changes associated with pregnancy, and the appropriate antiarrhythmic therapies available, almost all such cases can be treated successfully. Although no drug is completely safe, most are well tolerated and can be given with relatively low risk. Drug therapy should be avoided during the first trimester of pregnancy if possible and drugs with the longest record of safety should be used as first-line therapy. Conservative therapies should be used when appropriate. Several drug options exist for most maternal and fetal arrhythmias.

[Fetal arrhythmias: diagnosis, prognosis, treatment; apropos of 33 cases]

From October 1993 to February 1998, 33 cases of fetal cardiac arrhythmia were investigated by doppler-echocardiography at the Lille infantile and congenital cardiology department. Extrasystolic arrhythmias were the most frequently encountered disorder (25 fetuses, i.e., 76% of cases: 24 instances of extrasystolic auricular arrhythmia and one case of extrasystolic ventricular arrhythmia). They were invariably benign, and apart from one case only required standard monitoring. Tachycardia was observed in 15% of cases (three cases of supraventricular tachycardia [SVT] and two cases of auricular flutter [AF]). In no instance was a cardiopathic syndrome noted. A number of efficient treatments have been described, but the prognosis is often poor in the presence of hydrops fetalis. Direct fetal treatments (cordocentesis) are currently under evaluation, and at present can only be used as a last resort. In our series, one fetus died 15 minutes after transplacental Flecaine (flecainide) administration. Two of the three SVT and the two AF cases were successfully treated. Bradycardia, which was unassociated with extrasystolic arrhythmia, was found in 9% of cases. It is concluded that Flecaine is probably the treatment of choice for supraventricular and ventricular fetal tachycardia, as it has no teratogenic effect and crosses the placenta at a fetal concentration that is 80% of the maternal level. However, the administration of this drug is not without risk. It is known to possess certain negative side effects, and its pharmacological profile and maternal and fetal health risks have not yet been fully investigated. At present, no entirely safe and efficient treatment for fetal cardiac arrhythmia has been found.

Fetal supraventricular tachycardias: diagnosis and management

In the majority of cases, the diagnosis of an isolated fetal tachyarrhythmia results in a favorable perinatal outcome. Although there is general consensus on the management of fetal extrasystoles, refractory supraventricular tachycardia, and atrial flutter and fibrillation, the optimal approach to supraventricular tachycardia without hemodynamic compromise remains uncertain. The benefits of conservative management without antiarrhythmic therapy must be weighed carefully against the lack of reliable predictors for the development of fetal hydrops and associated neurologic complications.

Sotalol in the treatment of fetal dysrhythmias

BACKGROUND

Fetal tachycardia may cause hydrops fetalis and lead to fetal death. No unanimity of opinion exists regarding the optimum treatment. This study evaluates our experience with transplacental sotalol therapy to treat fetal tachycardias in terms of safety and efficacy.

METHODS AND RESULTS

The charts of 21 patients who were treated with sotalol for fetal tachycardia were reviewed. Ten fetuses had atrial flutter (AF), 10 had supraventricular tachycardia (SVT), and 1 had VT. Hydrops fetalis was present in 9 fetuses. Drug treatment was successful in establishing sinus rhythm in 8 of 10 fetuses with AF and in 6 of 10 fetuses with SVT. The mortality rate in this study was 19% (4 of 21 fetuses; 3 had SVT and 1 had AF); 3 deaths occurred just days after the initiation of sotalol therapy, and 1 occurred after a dosage increase. At birth, tachycardia was present in 6 infants. Two patients who converted to sinus rhythm in utero suffered from neurologic pathology postnatally.

CONCLUSIONS

Fetal tachycardia is a serious condition in which treatment should be initiated, especially in the presence of hydrops fetalis. The high success rate in fetuses with AF suggests that sotalol should be considered a drug of first choice to treat fetal AF. The low conversion rate and the fact that 3 of the 4 deaths in this study occurred in fetuses with SVT indicate that the risks of sotalol therapy outweigh the benefits in this group and that sotalol should, therefore, be limited in the treatment of fetal SVT.

Fetal arrhythmias

Fetal arrhythmias may be benign or life-threatening. Benign disturbances in fetal cardiac rhythm are relatively common, and their clinical manifestations are reviewed. Life-threatening fetal arrhythmias include supraventricular tachycardias, atrial flutter, ventricular or junctional tachycardia, chaotic atrial tachycardia, and bradyarrhythmias such as second or third degree AV block. The incidence, diagnostic characteristics and treatment of each of these are reviewed. In addition, the pathophysiology of hydrops fetalis, embryology of the conduction system and transplacental drug transfer characteristics are reviewed.

Nonimmune hydrops fetalis

Nonimmune hydrops fetalis (NIHF) is a term that defines an edematous fetus that does not have erythroblastosis fetalis from isoimmunization. All of the other reasons that a fetus develops NIHF are included in this category. The causes of NIHF range from diseases to structural anomalies to genetic abnormalities. The mere presence of NIHF is a poor prognostic indicator, even with the etiology unknown. Some causes of NIHF are treatable with intrauterine therapies. These currently include cordocentesis to administer intrauterine transfusions or medications and fetal surgery. Prenatal testing to establish an etiology or follow the progress of the fetus is extensive, expensive, and stressful. The mortality rate remains high. Education, counseling, and support of the patient and family are the work of the prenatal period. Delivery room management of the infant with NIHF requires a resuscitation team with a specific plan of care to maximize chances of survival.