Fetal arrhythmias: diagnosis and treatment

Fetal Heart Rate Auscultation, 4th Edition

Intermittent auscultation (IA) is an evidence-based method of fetal surveillance during labor for birthing people with low-risk pregnancies. It is a central component of efforts to reduce the primary cesarean rate and promote vaginal birth (American College of Obstetricians and Gynecologists, 2019; Association of Women's Health, Obstetric and Neonatal Nurses, 2022a). The use of intermittent IA decreased with the introduction of electronic fetal monitoring, while the increased use of electronic fetal monitoring has been associated with an increase of cesarean births. This practice monograph includes information on IA techniques; interpretation and documentation; clinical decision-making and interventions; communication; education, staffing, legal issues; and strategies to implement IA.

Fetal Heart Rate Auscultation, 4th Edition

Intermittent auscultation (IA) is an evidence-based method of fetal surveillance during labor for birthing people with low-risk pregnancies. It is a central component of efforts to reduce the primary cesarean rate and promote vaginal birth (American College of Obstetricians and Gynecologists, 2019; Association of Women's Health, Obstetric and Neonatal Nurses, 2022a). The use of intermittent IA decreased with the introduction of electronic fetal monitoring, while the increased use of electronic fetal monitoring has been associated with an increase of cesarean births. This practice monograph includes information on IA techniques; interpretation and documentation; clinical decision-making and interventions; communication; education, staffing, legal issues; and strategies to implement IA.

Prenatal Diagnosis of Fetal Heart Failure

Fetal heart failure (FHF) is a condition of inability of the fetal heart to deliver adequate blood flow for tissue perfusion in various organs, especially the brain, heart, liver and kidneys. FHF is associated with inadequate cardiac output, which is commonly encountered as the final outcome of several disorders and may lead to intrauterine fetal death or severe morbidity. Fetal echocardiography plays an important role in diagnosis of FHF as well as of the underlying causes. The main findings supporting the diagnosis of FHF include various signs of cardiac dysfunction, such as cardiomegaly, poor contractility, low cardiac output, increased central venous pressures, hydropic signs, and the findings of specific underlying disorders. This review will present a summary of the pathophysiology of fetal cardiac failure and practical points in fetal echocardiography for diagnosis of FHF, focusing on essential diagnostic techniques used in daily practice for evaluation of fetal cardiac function, such as myocardial performance index, arterial and systemic venous Doppler waveforms, shortening fraction, and cardiovascular profile score (CVPs), a combination of five echocardiographic markers indicative of fetal cardiovascular health. The common causes of FHF are reviewed and updated in detail, including fetal dysrhythmia, fetal anemia (e.g., alpha-thalassemia, parvovirus B19 infection, and twin anemia-polycythemia sequence), non-anemic volume load (e.g., twin-to-twin transfusion, arteriovenous malformations, and sacrococcygeal teratoma, etc.), increased afterload (intrauterine growth restriction and outflow tract obstruction, such as critical aortic stenosis), intrinsic myocardial disease (cardiomyopathies), congenital heart defects (Ebstein anomaly, hypoplastic heart, pulmonary stenosis with intact interventricular septum, etc.) and external cardiac compression. Understanding the pathophysiology and clinical courses of various etiologies of FHF can help physicians make prenatal diagnoses and serve as a guide for counseling, surveillance and management.

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.

Fetal Atrial Flutter Associated with Atrial Septal Aneurysm

Objective: To provide evidence that fetal atrial flutter (AF) caused by atrial septal aneurysm (ASA) can be completely cured by delivery. Methods: Cases series of three fetuses with ASA complicated by AF in late gestation, including hydrops fetalis in one case, were collected and completely followed up. Results: AF in all cases completely disappeared shortly after birth. New insights gained from this study are as follows: (1) PACs or bigeminy associated with ASA can progressively change to AF. (2) AF associated with ASA can cause hydrops fetalis and intrauterine treatment is needed; however, delivery is the definitive treatment. (3) AF associated with ASA completely resolves after birth. This is probably associated with changes in the circulation after birth, with no more blood flow crossing the foramen ovale and no turbulent flow in the ASA with reversal to hit the right atrial wall, activating ectopic pacemakers. Conclusions: This report may have clinical impact because it provides evidence that (1) in case of AF associated with ASA, the prognosis is much better than other causes and delivery should be strongly considered. (2) Fetuses diagnosed with AF should always be checked for the presence of ASA. (3) PAC/bigeminy related to ASA, different from isolated PAC, needs close follow-up for the development of SVT and AF. (4) Fetuses remote from term can benefit from intrauterine treatment to avoid hydrops fetalis, and to prolong gestation for maturity, early delivery is recommended once lung maturity is confirmed.

Efficacy and Safety of Various First-Line Therapeutic Strategies for Fetal Tachycardias: A Network Meta-Analysis and Systematic Review

Background: Fetal arrhythmias are common cardiac abnormalities associated with high mortality due to ventricular dysfunction and heart failure, particularly when accompanied by hydrops. Although several types of common fetal tachycardias have been relatively identified medications, such as digoxin, flecainide, and sotalol, there is no first-line drug treatment protocol established for the treatment of various types of fetal tachycardias.

Methods: We conducted a network meta-analysis using a Bayesian hierarchical framework to obtain a model for integrating both direct and indirect evidence. All tachycardia types (Total group), supraventricular tachycardia (SVT subgroup), atrial flutter (AF subgroup), hydrops subgroup, and non-hydrops subgroup fetuses were analyzed, and five first-line regimens were ranked according to treatment outcomes: digoxin monotherapy (D), flecainide monotherapy (F), sotalol monotherapy (S), digoxin plus flecainide combination therapy (DF), and digoxin plus sotalol combination therapy (DS). Effectiveness and safety were determined according to the cardioversion rate and intrauterine death rate.

Results: The pooled data indicated that DF combination therapy was always superior to D monotherapy, regardless of the tachycardia type or the presence of hydrops: Total, 2.44 (95% CrI: 1.59, 3.52); SVT, 2.77 (95% CrI: 1.59, 4.07); AF, 67.85 (95% CrI: 14.25, 168.68); hydrops, 6.03 (95% CrI: 2.54, 10.68); and non-hydrops, 5.06 (95% CrI: 1.87, 9.88). DF and F had a similar effect on control of fetal tachycardias. No significant differences were observed when comparing S, DS with D therapies across the subgroup analyses for the SVT, hydrops, and non-hydrops groups. No significant differences in mortality risks were among the various treatment regimens for the total group. And no significant differences were found in rates of intrauterine death rates at the same cardioversion amount.

Conclusion The flecainide monotherapy and combination of digoxin and flecainide should be considered the most superior therapeutic strategies for fetal tachycardia.

Systematic Review Registration: (https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=288997), identifier (288997).

Case report: Prenatal diagnosis of fetal non-compaction cardiomyopathy with bradycardia accompanied by de novo CALM2 mutation

We herein report what appears to be the first case of fetal non-compaction cardiomyopathy in both ventricles accompanied by a mutation in the calmodulin gene (CALM2). A 25-year-old woman was referred to our hospital at 25⁺¹ weeks of gestation for evaluation of fetal defects. Prenatal echocardiography showed biventricular non-compaction cardiomyopathy with sinus bradycardia. After termination of the pregnancy, fetal biventricular non-compaction cardiomyopathy was confirmed by autopsy and histopathologic examination. Additionally, whole-exome sequencing of genomic DNA demonstrated a de novo heterozygous mutation (c.389A > G; p.D130G) in CALM2, whereas the parents were normal. In this case report, we highlight the importance of prenatal ultrasound and genetic testing in fetal non-compaction cardiomyopathy with arrhythmia.

Prenatal Gene Therapy

Prenatal gene therapy could provide a cure for many monogenic diseases. Prenatal gene therapy has multiple potential advantages over postnatal therapy, including treating before the onset of disease, the ability to induce tolerance and cross the blood-brain barrier. In this chapter, we will describe in utero gene therapy and its rationale, clinical trials of postnatal gene therapy, preclinical studies of in utero gene therapy, and potential risks to the mother and fetus.

Clinical and genetic spectrum of neonatal arrhythmia in a NICU

BACKGROUND

Neonatal arrhythmia is a common complication that might be life-threatening or serious, but the genetic causes are unclear in most cases. The aim of this study is to investigate the genetic causes of neonatal arrhythmia in a NICU in China.

METHODS

Newborns who were diagnosed with arrhythmia during the neonatal period were enrolled from Children's Hospital of Fudan University between January 1st 2016, and December 31st, 2019. A neonatal gene panel was performed for each infant.

RESULTS

In total, 98 neonatal infants with arrhythmia were enrolled. Fourteen genes and a copy number change were identified and classified as pathogenic/likely pathogenic in 22 patients (22.4%), including 4 genes related to syndrome, 4 related to conduction, 2 related to metabolism, 2 related to structure, 2 related to respiration and immunity, respectively, and trisomy 21. Altogether, 6 genes (6/14, 42.9%) caused original heart structure or conduction abnormalities, leading to arrhythmia. Infants with ventricular tachycardia or fibrillation, atrioventricular block and long-QT syndrome all had positive gene results. The gene positive rate among arrhythmic infants with congenital heart disease or severe heart failure was higher than that of infants without congenital heart disease or severe heart failure.

CONCLUSIONS

The genetic disorders associated with neonatal arrhythmia could be syndrome-, conduction-, metabolism-, and structure-related. Infants with non-benign arrhythmia, especially ventricular tachycardia or fibrillation, long-QT syndrome, or high-grade atrioventricular block, have a higher rate of genetic abnormalities and should undergo genetic sequencing. Neonates with hereditary arrhythmias may have a higher risk of congenital heart disease or heart failure.

Challenge of managing opposing rhythms in a mother and fetus

INTRODUCTION

We report a case of a fetus with complex congenital heart disease and supraventricular tachycardia in the setting of maternal high grade atrioventricular block at 26 weeks' gestation.

METHODS AND RESULTS

Electroanatomic mapping allowed successful implantation of a permanent pacemaker to provide adequate back-up pacing in the mother with zero radiation exposure, thus allowing safe delivery of transplacental anti-arrhythmic medications to reduce the fetal arrhythmia burden and optimize the fetal ventricular rate.

CONCLUSION

This is the first reported case of using electroanatomic mapping, with zero fluoroscopy use, for pacemaker lead placement and for a novel indication.

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.