Fetal supraventricular tachycardias: diagnosis and management

Catheter ablation of typical right atrial flutter in a 20-day-old neonate with tachycardiomyopathy

Background

Fetal echocardiography can diagnose neonatal atrial flutter, which can cause heart failure in newborns. Little is known about catheter ablation in this population.

Methods

Case report that aimed to review a successful ablation in a 20-day-old patient with refractory atrial flutter.

Results

This is the first report of a successful neonatal atrial flutter ablation without any early recurrence after the procedure.

Conclusions

Atrial flutter ablation performed on newborns is a reliable and long-lasting treatment option.

Favourable outcome for hydrops or cardiac failure associated with fetal tachyarrhythmia: a 20-year review

BACKGROUND

Prognosis of fetuses with hydrops and tachyarrhythmia has been portrayed as poor in most published reports. This might lead to biased counselling, unnecessary caesarean section, preterm delivery, and even termination of pregnancy.

AIMS

To evaluate contemporary fetal and postnatal outcomes of hydropic fetuses with fetal tachyarrhythmia when it is treated effectively and monitored systematically.

METHODS

This is a retrospective review of a single centre experience at the University Hospital of Wales over a 20-year period. All fetuses received high doses of flecainide and digoxin combination treatment. Tachycardia response rate, time to arrhythmia and hydrops resolution, fetal and postnatal morbidity, and mortality rates were analysed.

RESULTS

Twenty fetuses were diagnosed with hydrops fetalis and received treatment. The mechanism of fetal tachyarrhythmia was supraventricular tachycardia in thirteen and atrial flutter in eight cases. Among the 20 fetuses treated, the overall tachycardia response rate was 90% (18/20) with the restoration of sinus rhythm in 85% (17/20) of the cases. The median time to restore sinus rhythm or to rate control of the arrhythmia was 1.5 days (range 12 hours to 13 days). Hydrops resolved in 17 of the 20 fetuses, with a median time of 12 days (range 3-21 days). Four fetuses went into spontaneous preterm birth and one fetus was delivered early due to worsening hydrops. No significant neurological morbidity was observed in surviving neonates and infants on clinical examination. There was one postnatal death due to respiratory complications of prematurity in the non-responsive supraventricular tachycardia case.

CONCLUSIONS

High-dose flecainide and digoxin combination offers effective treatment strategy in fetuses with hydrops and tachyarrhythmia with favourable outcomes. This study may guide more realistic counselling for pregnancies complicated by tachyarrhythmia and hydrops.

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.

Fetal Supraventricular Tachycardia: What the Adult Cardiologist Needs to Know

Fetal supraventricular tachycardia management is challenging, with consequences for both the fetus and the mother. If left untreated, fetal hydrops may ensue, at which point delivery and treatment of the arrhythmia is preferred. However, if the fetus is not at term nor near-term, significant doses of antiarrhythmics may be needed to achieve adequate transplacental bioavailability. Although digoxin has classically been the mainstay of treatment, the use of flecainide or sotalol as monotherapy or in combination with digoxin is being studied. Interdisciplinary team management and shared decision-making between the physician and patient are key to achieving successful outcomes. Adult cardiologists, particularly inpatient consultation services or through burgeoning cardio-obstetrics programs, may, in some practice settings, be asked to evaluate or comanage pregnant women with fetal arrhythmia.

Treatment of Fetal Arrhythmias

Fetal arrhythmias are mostly benign and transient. However, some of them are associated with structural defects or can cause heart failure, fetal hydrops, and can lead to intrauterine death. The analysis of fetal heart rhythm is based on ultrasound (M-mode and Doppler echocardiography). Irregular rhythm due to atrial ectopic beats is the most common type of fetal arrhythmia and is generally benign. Tachyarrhythmias are diagnosed when the fetal heart rate is persistently above 180 beats per minute (bpm). The most common fetal tachyarrhythmias are paroxysmal supraventricular tachycardia and atrial flutter. Most fetal tachycardias can be terminated or controlled by transplacental or direct administration of anti-arrhythmic drugs. Fetal bradycardia is diagnosed when the fetal heart rate is slower than 110 bpm. Persistent bradycardia outside labor or in the absence of placental pathology is mostly due to atrioventricular (AV) block. Approximately half of fetal heart blocks are in cases with structural heart defects, and AV block in cases with structurally normal heart is often caused by maternal anti-Ro/SSA antibodies. The efficacy of prenatal treatment for fetal AV block is limited. Our review aims to provide a practical guide for the diagnosis and management of common fetal arrythmias, from the joint perspective of the fetal medicine specialist and the cardiologist.

Fetal Tachycardia in the Delivery Room: Fetal Distress, Supraventricular Tachycardia, or Both?

Background  Supraventricular tachycardia (SVT) is seldom considered a cause for fetal tachycardia; commoner etiologies including maternal fever and fetal distress are usually envisaged. Fetal arrhythmia can be missed as a diagnosis, potentially leading to suboptimal management. Cases  Three cases are described where detection of fetal tachycardia >200 beats per minute (bpm) at 36, 40, and 38 weeks gestation resulted in emergency cesarean section for presumed fetal distress. Retrospective review of the cardiotocograph in two cases revealed baseline heart rates 120 to 160 bpm, with loss of trace associated with auscultated rates over 200 bpm. The diagnosis of SVT was not initially considered and made later when the infants required cardioversion at the age of 3 weeks, 2 days, and 8 days, respectively. The 36-week infant required noninvasive ventilation for prematurity. Conclusion  SVT should be actively considered in the differential diagnosis of fetal tachycardia. Unrecognized fetal SVT may result in avoidable caesarean for suspected fetal distress, with potential prematurity-related problems. The cardiotocograph can be helpful if showing contact loss associated with rapid heart rate auscultation. The antenatal detection of fetal SVT is important as it can allow anticipation and prevention of neonatal SVT, which is potentially life-threatening if not detected and treated promptly.

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.

Low mortality in fetal supraventricular tachycardia: Outcomes in a 30-year single-institution experience

OBJECTIVES

To describe a single institutional experience managing fetuses with supraventricular tachycardia (SVT) and to identify associations between patient characteristics and fetal and postnatal outcomes.

BACKGROUND

Sustained fetal SVT is associated with significant morbidity and mortality if untreated, yet the optimal management strategy remains unclear.

METHODS

Retrospective cohort study including fetuses diagnosed with sustained SVT (>50% of the diagnostic echocardiogram) between 1985 and 2018. Fetuses with congenital heart disease were excluded.

RESULTS

Sustained SVT was diagnosed in 65 fetuses at a median gestational age of 30 weeks (range, 14-37). Atrioventricular re-entrant tachycardia and atrial flutter were the most common diagnoses, seen in 41 and 16 cases, respectively. Moderate/severe ventricular dysfunction was present in 20 fetuses, and hydrops fetalis was present in 13. Of the 57 fetuses initiated on transplacental drug therapy, 47 received digoxin first-line, yet 39 of 57 (68%) required advanced therapy with sotalol, flecainide, or amiodarone. Rate or rhythm control was achieved in 47 of 57 treated fetuses. There were no cases of intrauterine fetal demise. Later gestational age at fetal diagnosis (odds ratio [OR], 1.1, 95% confidence interval [CI], 1.01-1.2, P = .02) and moderate/severe fetal ventricular dysfunction (OR, 6.1, 95% CI, 1.7-21.6, P = .005) were associated with postnatal SVT. Two postnatal deaths occurred.

CONCLUSIONS

Fetuses with structurally normal hearts and sustained SVT can be effectively managed with transplacental drug therapy with minimal risk of intrauterine fetal demise. Treatment requires multiple antiarrhythmic agents in over half of cases. Later gestational age at fetal diagnosis and the presence of depressed fetal ventricular function, but not hydrops, predict postnatal arrhythmia burden.

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.

Postnatal outcome in patients with fetal tachycardia

The diagnosis and management of prenatal tachyarrhythmias is well established; however, the postnatal course and outcomes are not. The purpose of our study was to review the natural history of patients with fetal tachycardia, determine the incidence of postnatal arrhythmias, and determine whether there are factors to predict which fetuses will develop postnatal arrhythmias. A retrospective chart review of patients with fetal tachyarrhythmias investigated at British Columbia Children's and Women's Hospitals between 1983 and 2010 was conducted. Sixty-nine mother-fetus pairs were eligible for the study. Fifty-two had fetal supraventricular tachycardia, and 17 had fetal atrial flutter. Conversion to sinus rhythm occurred prenatally in 52 % of patients. Postnatal arrhythmia occurred in two thirds of patients, with 82 % of those cases occurring within the first 48 h of life. Hydrops fetalis, female sex, and lack of conversion to sinus rhythm was predictive of postnatal arrhythmia (P = 0.01, P = 0.01, and P = 0.001, respectively). Conversion to sinus rhythm prenatally did not predict postnatal arrhythmia. Median duration of treatment was 9 months. Two postnatal deaths of unknown etiology occurred. Two thirds of all patients with prenatal tachycardia will develop postnatal arrhythmia. Prenatal factors that predict postnatal arrhythmia include hydrops, sex, and whether or not conversion to sinus rhythm occurred prenatally. The majority of patients with postnatal arrhythmia present within 48 h of life, which has clinical implications for monitoring. Postnatal outcome is generally very good with most patients being weaned off medication in 6-12 months.

Prenatal diagnosis, management and outcome of fetal dysrhythmia: a tertiary fetal medicine centre experience over an eight-year period

OBJECTIVE

To review the prenatal diagnosis, management and outcome of fetal dysrhythmia.

SUBJECTS AND METHODS

Prenatal diagnosis, management and outcomes of fetuses with dysrhythmia were reviewed retrospectively (01/01/1997 to 31/12/2004).

RESULTS

Over an 8-year period, 318 pregnant mothers were referred for assessment of suspected fetal dysrhythmias. Median gestation was 30 weeks (range 19-41). Fetal dysrhythmia was identified in 182 (57%) and classified as: (i) 126 atrial extrasystoles; (ii) 26 tachyarrhythmia, and (iii) 30 bradyarrhythmia. Of the fetuses with tachyarrhythmia, 23 had supraventricular tachycardia (SVT), 2 atrial flutter and 1 sinus tachycardia. One death associated with severe hydrops occurred in the tachyarrhythmia group. 19 cases of SVT were successfully treated in utero. Both cases of atrial flutter required direct current cardioversion in the neonatal period. In the bradyarrhythmia group, there were 15 isolated cases and 10 cases associated with congenital heart disease, with 73 and 20% survival, respectively.

CONCLUSIONS

Benign atrial extrasystoles are the commonest cause for referral and assessment of fetal dysrhythmia. The overall prognosis for SVT is good with the majority responding to transplacental therapy. In cases with congenital atrioventricular block, the outcome was less favourable, especially when the atrioventricular block was associated with congenital heart disease.

Nonimmune hydrops fetalis part I: etiology and pathophysiology

Nonimmune hydrops fetalis (NIHF) is a condition in which excess fluid has accumulated in the fetal interstitial spaces as a result of one or more nonimmune factors. A plethora of maternal, placental, and fetal disease processes have been associated with NIHF. Knowledge of the various etiologies of NIHF and how the disease process affects fluid homeostasis is important for planning patient care and counseling families of patients diagnosed with nonimmune hydrops fetalis. This article discusses the mechanisms governing fluid distribution in the extracellular spaces, examines the various etiologies associated with NIHF, and describes the pathogenesis of NIHF for each etiologic category.

Assessment of fetal autonomic nervous system activity by fetal magnetocardiography: comparison of normal pregnancy and intrauterine growth restriction

OBJECTIVE

To clarify the developmental activity of the autonomic nervous system (ANS) of the normal fetus and intrauterine growth restriction (IUGR) cases using fetal magnetocardiography (FMCG).

SUBJECTS AND METHODS

Normal pregnancy (n = 35) and IUGR (n = 12) cases at 28-39 and 32-37 weeks of gestation, respectively, were included in this study. The R-R interval variability was used to calculate the coefficient of variance (CV(RR)) and low frequency/high frequency (LF/HF) ratio.

RESULTS

The value of CV(RR) in the normal pregnancy group displayed a slight increasing trend with gestational age. However, no such trend was observed in the IUGR group. In contrast, the LF/HF ratio in both the normal pregnancy group and the IUGR group clearly increased over the gestational period; the normal group showing statistical significance.

CONCLUSION

The development of fetal ANS activity in IUGR cases might differ from that observed in the normal pregnancy group, and this may facilitate early detection of IUGR.

Prenatal diagnosis of congenital heart disease

This article presents advancements in the field of fetal echocardiography and the significant impact of these within the fields of pediatric cardiology, perinatology, and neonatology. A prenatal diagnosis of congenital heart disease allows for improved counseling of the parents, guides the timing and optimal location of delivery, and allows appropriate planning and consultation between the cardiologist and neonatologist. It also facilitates accurate diagnosis and management of fetal arrhythmias, identifies potential candidates for in utero cardiac intervention, and serves as the imaging guidance technique for these procedures. The goals, indications, advantages, limitations, and spectrum of congenital heart disease that can be diagnosed are reviewed.

Fetal echocardiography: where are we?

This article reviews the indications, technique and benefits of fetal echocardiography. The impact of fetal echocardiography has become evident with better surgical outcome of infants with prenatal diagnosis of congenital heart disease. A major use of this technique has also been shown in the field of fetal arrhythmias. Fetal echocardiography is not only used to diagnose a specific type of arrhythmia, it is also very helpful in assessing the effect of the arrhythmia on the fetus and in guiding transplacental therapy. However it is important to remember that even experienced echocardiographers can make both false positive and false negative diagnosis of congenital heart disease. As fetal cardiac interventions including fetal cardiac surgery loom on the horizon, fetal echocardiography assumes further importance.

Fetal arrhythmias: natural history and management

The aim was to delineate the significance and natural history of fetal arrhythmias and provide information about their management. A cohort of 114 infants with fetal arrhythmias detected during prenatal ultrasound (US) screening were studied. All subjects underwent echocardiography and were treated as clinically indicated. Postnatal outcome was obtained in 100% of infants until 1 year of age. The incidence of fetal arrhythmias was 0.3%. Among the 87 fetuses with atrial extrasystoles, 2.3% developed supraventricular tachycardia (SVT) in utero. Of the 10 SVT cases, only five required antiarrhythmic therapy in utero with digoxin and propafenone, which successfully restored sinus rhythm in 100% of fetuses, both nonhydropic and hydropic. Sinus bradycardia was associated with structural anomalies in 5 of 6 patients and only 2 of 4 fetuses with atrioventricular block survived. It is concluded that prognosis is good for most fetal tachyarrhythmias, whereas it is less favorable for bradyarrhythmias.

Influenza A virus infection and cardiac arrhythmia during the neonatal period

Influenza virus infection during pregnancy increases the risk of spontaneous abortion, preterm contractions, fetal compromise and early neonatal mortality. We describe a case of fetal and neonatal cardiac arrhythmia coinciding with an influenza A virus infection. Viral RNA was detected in the neonate's nasopharyngeal secretions and also in its serum, indicating influenza viremia. The cardiac arrhythmia resolved spontaneously without antiarrhythmic treatment.