Congenital junctional ectopic tachycardia and congenital complete atrioventricular block: A shared etiology?

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.

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.

Junctional ectopic tachycardia (JET)

Junctional ectopic tachycardia (JET) is a tachyarrhythmia arising from the atrioventricular node and His bundle area. Enhanced normal automaticity has been postulated as the mechanism of JET in the majority of patients. It is more common in children and can be seen as congenital or in postoperative settings. It is often a narrow complex tachycardia but can present as a wide complex tachycardia as a result of aberrant conduction. Its differentiation from other arrhythmias especially atrioventricular nodal reentrant tachycardia (AVNRT) can be challenging. Medical treatment of JET is difficult, and catheter ablation remains the mainstay of treatment in refractory cases with a high risk of atrioventricular block and recurrence.

Junctional ectopic tachycardia in infants and children

Tachyarrhythmias originating in the atrioventricular (AV) node and AV junction including the bundle of His complex (BH) are called junctional tachycardia (JT) or junctional ectopic tachycardia (JET). Congenital JET (CJET) is a rare arrhythmia that occurs in patients without a preceding cardiac surgery and can be refractory to medical therapy and associated with high morbidity and mortality. CJET has a high rate of morbidity and mortality with death occurring in 35% of cases. JET occurring within 72 hours after cardiac surgery is referred to as postoperative JET (POJET) and caused by direct trauma, ischemic, or stretch injury to the AV conduction tissues during surgical repair of congenital heart defects. Focal junctional tachycardia (FJT) is also known as automatic junctional tachycardia and includes paroxysmal or non-paroxysmal forms. We discuss a staged approach to therapy with improved pharmacological therapies and the use of catheter-based therapies.

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.

Hemodynamics in fetal arrhythmia

Fetal arrhythmias are among the few conditions that can be managed in utero. However, accurate diagnosis is essential for appropriate management. Ultrasound-based imaging methods can be used to study fetal heart structure and function noninvasively and help to understand fetal cardiovascular pathophysiology, and they remain the mainstay of evaluating fetuses with arrhythmias in clinical settings. Hemodynamic evaluation using Doppler echocardiography allows the elucidation of the electrophysiological mechanism and helps to make an accurate diagnosis. It can also be used as a tool to understand fetal cardiac pathophysiology, for assessing fetal condition and monitoring the effect of antiarrhythmic treatment. This narrative review describes Doppler techniques that are useful for evaluating fetal cardiac rhythms to refine diagnosis and provides an overview of hemodynamic changes observed in different types of fetal arrhythmia.

Association of temporary complete AV block and junctional ectopic tachycardia after surgery for congenital heart disease

AIM

Junctional ectopic tachycardia (JET) is a postoperative complication with a mortality rate of up to 14% after surgery for congenital heart disease. This study evaluated the risk factors of JET and explored the association of postoperative temporary third degree atrioventricular (AV) block and the occurrence of JET.

MATERIALS AND METHODS

Data were collected retrospectively from 1158 patients who underwent surgery for congenital heart disease.

RESULTS

The overall incidence of JET was 2.8%. Temporary third degree AV block occurred in 1.6% of cases. Permanent third degree AV block requiring pacemaker implantation occurred in 1% of cases. In all, 56% of patients with JET had temporary AV block (P < 0.001), whereas no case of postoperative JET was reported in patients with permanent AV block (P = 0.56). temporary third degree AV block did not suffer from JET.

CONCLUSIONS

A correlation between temporary third degree AV block and postoperative JET could be observed. The risk factors identified for JET include younger age groups at the time of surgery, longer aortic cross clamping time and surgical procedures in proximity to the AV node.

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.

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.

Magnetocardiography-guided management of an unusual case of isoimmune complete atrioventricular block complicated by ventricular tachycardia

A fetus who was diagnosed at 25 weeks of gestation with isoimmune AV block presented at 34 weeks with a precipitous fall in ventricular rate and periods of tachycardia. Magnetocardiography revealed the tachycardia to be ventricular. After delivery, nonsustained ventricular tachycardia continued. The baby then successfully paced, and at higher ventricular rates the tachycardia resolved. Five years later the child has normal ventricular function and is doing well.

Electrophysiological characteristics of fetal atrioventricular block

OBJECTIVES

The purpose of our work was to define the complex electrophysiological characteristics seen in second- (2 degrees) and third-degree (3 degrees) atrioventricular block (AVB) and to longitudinally follow the development of atrial and ventricular heart rate and rhythm patterns with a goal of identifying heart rate and rhythm patterns associated with urgent delivery or neonatal pacing.

BACKGROUND

The electrophysiological characteristics of congenital AVB before birth have not been extensively studied, yet the mortality from this disease is substantial. Along with advances in fetal therapies and interventions, a comprehensive natural history specific to the etiology of AVB, as well as the electrophysiological factors influencing outcome, are needed to best select treatment options.

METHODS

Twenty-eight fetuses with AVB were evaluated by fetal magnetocardiography; 21 fetuses were evaluated serially.

RESULTS

Fetuses with 2 degrees AVB and isolated 3 degrees AVB showed: 1) diverse atrial rhythms and mechanisms of atrioventricular conduction during 2 degrees AVB; 2) junctional ectopic tachycardia and ventricular tachycardia during 3 degrees AVB; 3) reactive ventricular and atrial fetal heart rate (FHR) tracings at ventricular rates >56 beats/min; and 4) flat ventricular FHR tracings at ventricular rates <56 beats/min despite reactive atrial FHR tracings. In contrast, fetuses with 3 degrees AVB associated with structural cardiac disease exhibited predominantly nonreactive heart rate tracings and simpler rhythms.

CONCLUSIONS

Second-degree AVB, isolated 3 degrees AVB, and 3 degrees AVB associated with structural cardiac disease manifest distinctly different electrophysiological characteristics and outcome. Fetuses with 2 degrees AVB or isolated 3 degrees AVB commonly exhibited complex, changing heart rate and rhythm patterns; all 19 delivered fetuses are alive and healthy. Fetuses with structural cardiac disease and 3 degrees AVB exhibited largely monotonous heart rate and rhythm patterns and poor prognosis. Junctional ectopic tachycardia and/or ventricular tachycardia may be characteristic of an acute stage of heart block.

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.

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.