Fetal ventricular tachycardia secondary to long QT syndrome treated with maternal intravenous magnesium: case report and review of the literature

Fetal Long QT Syndrome - Challenges in Perinatal Management: A Review and Case Report. Induction of Labor and Vaginal Birth Under Continuous Magnesium Therapy

Congenital LQTS is an often undetected inherited cardiac channel dysfunction and can be a reason for intrauterine fetal demise. It can present in utero as CTG and ultrasound abnormalities, i. e., bradycardia, ventricular tachycardia, or fetal hydrops. Diagnosis is made by CTG, echocardiography, or fMCG. Intrauterine therapy with a ß blocker and i. v. magnesium should be started. Our objective was to examine the current knowledge about diagnosis and treatment of LQTS and in particular to highlight the opportunity of vaginal birth under continuous intravenous magnesium therapy. Therefore, a thorough MEDLINE and Google Scholar search was conducted. Randomized controlled trials, meta-analyses, prospective and retrospective cohort trials, and case reports were considered. We showed the possibility of vaginal delivery under continuous magnesium therapy in a case of suspected fetal LQTS. A stepwise concept for diagnosis, monitoring, and peripartum management in low, intermediate, and high risk cases of fetal LQTS is presented. If risk is low or intermediate, a vaginal delivery under continuous monitoring is reasonable. Induction of labor at term should be evaluated.

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.

Abnormal Microscopic Findings in the Placenta Correlate With the Severity of Fetal Heart Failure

BACKGROUND

This study investigated the association between placental pathology and fetal heart failure.

METHODS AND RESULTS

Singletons with a congenital heart defect (CHD) and/or arrhythmia (n=168) and gestational age-matched controls (n=52) were included in the study. The associations between macro- and microscopic abnormal findings of the placenta and the severity of fetal heart failure were evaluated using the cardiovascular profile (CVP) score. Nine features were microscopically identified and assessed in sections of the placenta: premature villi, edematous villi, fibrotic villi, chorioamnionitis, chorangiosis, fibrin deposition, subchorionic hematoma, infarcted villi, and nucleated red blood cells in villous vessels. Among singletons with CHD and/or arrhythmia, the final CVP score was ≥8 in 140 cases, 6 or 7 in 15 cases, and ≤5 in 13 cases. Microscopic analysis showed that the frequency and severity of premature and edematous villi and increased nucleated red blood cells in villous vessels were greater in cases of fetal heart failure. These microscopic findings were more common and severe in cases with a final CVP score ≤5 than in gestational age-matched controls. The prevalence of abnormal macroscopic findings of the placenta and umbilical cord was similar regardless of the severity of fetal heart failure.

CONCLUSIONS

Premature and edematous villi and increased nucleated red blood cells in villous vessels were correlated with the severity of fetal heart failure in cases of CHD and/or arrhythmia.

Systematic review of long QT syndrome identified during fetal life

Fetal long QT syndrome (LQTS) may present with sinus bradycardia, functional 2:1 atrioventricular block (AVB), and ventricular arrhythmias (ventricular tachycardia [VT]/torsades de pointes [TdP]) and lead to fetal or postnatal death. We performed a systematic review and individual participant data meta-analysis of 83 studies reporting outcomes of 265 fetuses for which suspected LQTS was confirmed postnatally and determined risk of adverse perinatal and postnatal outcomes using logistic and stepwise logistic regression. A longer fetal QTc was more predictive of death than any other antenatal factor (receiver operating characteristic [ROC] area under the curve [AUC] 0.85; 95% confidence interval [CI] 0.66-1.00). Risk of death was significantly increased with fetal QTc >600 ms. Neither fetal heart rate nor heart rate z-score predicted death (ROC AUC 0.51; 95% CI 0.31-0.71; and ROC AUC 0.59; 95% CI 0.37-0.80, respectively). The combination of antenatal VT/TdP or functional 2:1 AVB and lack of family history of LQTS was also highly predictive of death (ROC AUC 0.82; 95% CI 0.76-0.88). Our data provide clinical screening tools to enable prediction and intervention for fetuses with LQTS at risk of death.

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.

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 ventricular tachycardia: betablockers should be the first line treatment

Ventricular tachycardia (VT) is a rare cause of tachycardia during the fetal life. Coexistence of VT with sinus bradycardia or second-degree heart block strongly suggests long QT syndrome (LQTS) [1-3] and needs to administrate to the mother beta-blockers and in some cases magnesium sulfate [1,2,4]. When there is no argument for a LQTS several drugs have been proposed, most of them contraindicated in LQTS. We present a case of fetal LQTS with fetal VT and cardiac insufficiency with no antenatal clue for LQTS, successfully managed with propranolol. Thus, we suggest that in case of isolated fetal VT (i.e. without tumor or cardiomyopathy) beta blockers (excluding sotalol) should be the first line treatment since LQTS can be a possible cause for the dysrhythmia.

Noninvasive Fetal Electrocardiography in the Diagnosis of Long QT Syndrome: A Case Series

INTRODUCTION

Early detection and monitoring for malignant arrhythmias is fundamental to prenatal care in long QT syndrome (LQTS). Recently, we studied the feasibility of isolating the fetal electrocardiogram (fECG) and measuring electrocardiographic intervals with a noninvasive fECG device using blind source separation with reference signal. Our aim was to evaluate the ability of fECG to diagnose LQTS.

CASE PRESENTATIONS

We identified 3 cases of clinically suspected LQTS based on fetal echocardiogram (2 had sinus bradycardia, 1 had second-degree atrioventricular block with negative maternal anti-SSA/SSB antibody titers). With institutional review board approval, these patients were prospectively enrolled for fECG acquisition. Offline post-processing generated fECG waveforms and calculated QT intervals. Case 1 and 3 had a maternal history of LQTS. Two of the three fetuses with suspected LQTS had confirmed LQTS by postnatal ECG and genetic testing. FECG was able to identify a prolonged corrected QT interval in both cases. One of these also had fetal magnetocardiography (fMCG), which yielded similar findings to the fECG. The third fetus had a normal fECG; fMCG and postnatal ECG were also normal.

CONCLUSIONS

In 3 cases, fECG findings corroborated the diagnosis of LQTS. Noninvasive fECG may offer a novel method for fECG that is portable and more clinically accessible.

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

OBJECTIVES

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Left Ventricular Isovolumetric Relaxation Time Is Prolonged in Fetal Long-QT Syndrome

BACKGROUND

Long-QT syndrome (LQTS), an inherited cardiac repolarization disorder, is an important cause of fetal and neonatal mortality. Detecting LQTS prenatally is challenging. A fetal heart rate (FHR) less than third percentile for gestational age is specific for LQTS, but the sensitivity is only ≈50%. Left ventricular isovolumetric relaxation time (LVIRT) was evaluated as a potential diagnostic marker for fetal LQTS.

METHODS AND RESULTS

LV isovolumetric contraction time, LV ejection time, LVIRT, cycle length, and FHR were measured using pulsed Doppler waveforms in fetuses. Time intervals were expressed as percentages of cycle length, and the LV myocardial performance index was calculated. Single measurements were stratified by gestational age and compared between LQTS fetuses and controls. Receiver-operator curves were performed for FHR and normalized LVIRT (N-LVIRT). A linear mixed-effect model including multiple measurements was used to analyze trends in FHR, N-LVIRT, and LV myocardial performance index. There were 33 LQTS fetuses and 469 controls included. In LQTS fetuses, the LVIRT was prolonged in all gestational age groups (P<0.001), as was the N-LVIRT. The best cutoff to diagnose LQTS was N-LVIRT ≥11.3 at ≤20 weeks (92% sensitivity, 70% specificity). Simultaneous analysis of N-LVIRT and FHR improved the sensitivity and specificity for LQTS (area under the curve=0.96; 95% confidence interval, 0.82-1.00 at 21-30 weeks). N-LVIRT, LV myocardial performance index, and FHR trends differed significantly between LQTS fetuses and controls through gestation.

CONCLUSIONS

The LVIRT is prolonged in LQTS fetuses. Findings of a prolonged N-LVIRT and sinus bradycardia can improve the prenatal detection of fetal LQTS.

Fetal arrhythmias: Diagnosis and management

This article reviews important features for improving the diagnosis and management of fetal arrhythmias. The normal fetal heart rate ranges between 110 and 160 beats per minute. A fetal heart rate is considered abnormal if the heart rate is beyond the normal ranges or the rhythm is irregular. The rate, duration, and origin of the rhythm and degree of irregularity usually determine the potential for hemodynamic consequences. Most of the fetal rhythm disturbances are the result of premature atrial contractions (PACs) and are of little clinical significance. Other arrhythmias include tachyarrhythmias (heart rate in excess of 160 beats/min) such as atrioventricular (AV) reentry tachycardia, atrial flutter, and ventricular tachycardia, and bradyarrhythmias (heart rate <110 beats/min) such as sinus node dysfunction, complete heart block (CHB) and long QT syndrome (which is associated with sinus bradycardia and pseudo-heart block).

Ventricular Tachycardia in a Fetus: Benign Course of a Malignant Arrhythmia

Background

Fetal arrhythmias constitute 10 to 20% of the total referrals to fetal cardiology unit. Ventricular tachycardia (VT) is a rare form of fetal tachyarrhythmia.

Materials and methods

This report describes the clinical presentation, diagnostic features, and successful management of VT in a fetus at 32 weeks of gestation. Transplacental therapy with sotalol resulted in the termination of tachyarrhythmia in 48 h, followed by good postnatal outcome.

Conclusion

Fetal m-mode showing ventricular rate higher than atrial rate with atrio-ventricular dissociation is suggestive of VT. Early diagnosis and institution of transplacental therapy prior to development of hydrops seem to carry a good prognosis even in malignant fetal arrhythmias like VT.

Prenatal therapy for fetal cardiac disorders

Fetal cardiac abnormalities are some of the commonest congenital disorders seen in prenatal life. They can be anatomical or functional and can develop de novo or as a consequence of either maternal or fetal disease. Untreated, morbidity and mortality rates are high for hypoplastic left heart disorders and for some fetal tachy and bradyarrhythmias. Optimum management strategies are often not clear because of the lack of knowledge about the precise natural history of some of these conditions. Prenatal therapy ranges from invasive fetal cardiac intervention to maternal administration of drugs for transplacental transfer to the fetus. This comprehensive review covers many fetal cardiac disorders and various prenatal therapeutic options that are available.

A Potential Diagnostic Approach for Foetal Long-QT Syndrome, Developed and Validated in Children

In patients with Long-QT Syndrome (LQTS), mechanical abnormalities have been described. Recognition of these abnormalities could potentially be used in the diagnosis of LQTS, especially in the foetus where an ECG is not available and DNA-analysis is invasive. We aimed to develop and validate a marker for these mechanical abnormalities in children and to test its feasibility in foetuses as a proof of principle. We measured the myocardial contraction duration using colour Tissue Doppler Imaging (cTDI) in 41 LQTS children and age- and gender-matched controls. Children were chosen to develop and validate the measurement of the myocardial contraction duration, due to the availability of a simultaneously recorded ECG. Feasibility of this measurement in foetuses was tested in an additional pilot study among seven LQTS foetuses and eight controls. LQTS children had a longer myocardial contraction duration compared to controls, while there was no statistical difference in heart rate. Measuring the myocardial contraction duration in children had a high inter- and intra-observer validity and reliably correlated with the QT-interval. There was an area under the curve (AUC) of 0.71, and the optimal cut-off value showed an especially high specificity in diagnosing LQTS. Measuring the myocardial contraction duration was possible in all foetuses and had a high inter- and intra-observer validity (ICC = 0.71 and ICC = 0.88, respectively). LQTS foetuses seemed to have a longer myocardial contraction duration compared to controls. Therefore, a prolonged contraction duration may be a potential marker for the prenatal diagnosis of LQTS in the future. Further studies are required to support the measurement of the myocardial contraction duration as a diagnostic approach for foetal LQTS.

Modification of distinct ion channels differentially modulates Ca2+ dynamics in primary cultured rat ventricular cardiomyocytes

Primary cultured cardiomyocytes show spontaneous Ca²⁺ oscillations (SCOs) which not only govern contractile events, but undergo derangements that promote arrhythmogenesis through Ca²⁺ -dependent mechanism. We systematically examined influence on SCOs of an array of ion channel modifiers by recording intracellular Ca²⁺ dynamics in rat ventricular cardiomyocytes using Ca²⁺ specific fluorescence dye, Fluo-8/AM. Voltage-gated sodium channels (VGSCs) activation elongates SCO duration and reduces SCO frequency while inhibition of VGSCs decreases SCO frequency without affecting amplitude and duration. Inhibition of voltage-gated potassium channel increases SCO duration. Direct activation of L-type Ca²⁺ channels (LTCCs) induces SCO bursts while suppressing LTCCs decreases SCO amplitude and slightly increases SCO frequency. Activation of ryanodine receptors (RyRs) increases SCO duration and decreases both SCO amplitude and frequency while inhibiting RyRs decreases SCO frequency without affecting amplitude and duration. The potencies of these ion channel modifiers on SCO responses are generally consistent with their affinities in respective targets demonstrating that modification of distinct targets produces different SCO profiles. We further demonstrate that clinically-used drugs that produce Long-QT syndrome including cisapride, dofetilide, sotalol, and quinidine all induce SCO bursts while verapamil has no effect. Therefore, occurrence of SCO bursts may have a translational value to predict cardiotoxicants causing Long-QT syndrome.

Clinical spectrum of fetal long QT syndrome: a single-center experience

OBJECTIVE

A considerable proportion of unexplained intrauterine fetal deaths are attributed to long QT syndrome (LQTS) susceptibility. Additionally, the estimated prevalence of LQTS in newborns is 1 in 2000. Still, prenatal diagnosis of LQTS is very rare. The aim of this study was to assess the frequency of prenatal diagnosis of LQTS at our institution, present the cases, compare our findings with the existing literature and propose a possible screening approach.

METHODS

We searched our fetal database between 2006 and 2013 for cases with suspected diagnosis of LQTS.

RESULTS

During the investigation period around 26 000 fetuses were evaluated and three cases of suspected fetal LQTS identified. Two cases of familial LQTS had no or mild intrauterine manifestation of the condition, the third fetus had a de-novo mutation with severe, early-onset disease.

CONCLUSIONS

LQTS continues to be a challenging prenatal diagnosis. In fetuses who present with complex arrhythmias, a high degree of suspicion is required, and close surveillance and timely delivery in the presence of a multidisciplinary team are necessary. For asymptomatic cases or screening purposes, routine fetal heart rate registration and detailed assessment of cases with a low for gestational age baseline may be an option.

Comorbid Epilepsy and Developmental Disorders in Congenital Long QT Syndrome With Life-Threatening Perinatal Arrhythmias

OBJECTIVES

Given the association of long QT syndrome (LQTS) and neurological disorders, we speculated that the more severe LQTS phenotype, perinatal LQTS, would exhibit more frequent comorbid neurodevelopmental anomalies than LQTS without perinatal arrhythmias (nonperinatal LQTS).

BACKGROUND

Congenital LQTS with life-threatening perinatal arrhythmias (perinatal LQTS) has a poor life prognosis.

METHODS

Twenty-one consecutive LQTS patients diagnosed before 1 year of age at our institution and 3 previously reported perinatal LQTS patients with neurological seizures were enrolled. In total, the clinical course was evaluated in 24 patients.

RESULTS

Among 21 infantile LQTS patients, 5 of 6 with perinatal LQTS (83%) were diagnosed with epilepsy and 4 (67%) with developmental disorders, but none with nonperinatal LQTS were. The total development quotient by Kinder Infant Development Scale scores was 17 to 72 (median 67) in 5 epileptic perinatal LQTS. In the 8 perinatal LQTS patients with neurological disorders, including 3 previously reported cases, epileptic seizures occurred at 2 days to 2.5 years of age and 5 had developmental disorders. Mutations in these 8 patients were located in the transmembrane loop of KCNH2, and D3/S4-S5 linker, D4/S4, or the D4/S6 segment of SCN5A.

CONCLUSIONS

A high comorbidity of neurodevelopmental anomalies was observed in perinatal LQTS. Mutations in patients with neurological comorbidities were in loci linked to LQTS with a severe cardiac phenotype. These observations indicate the possibility that neurological disorders in perinatal LQTS are manifested as neurological phenotypes associated with severe cardiac phenotypes, while we could not completely exclude another possibility that those were caused by a brain perfusion injury.

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.

Cardiotoxicity screening: a review of rapid-throughput in vitro approaches

Cardiac toxicity represents one of the leading causes of drug failure along different stages of drug development. Multiple very successful pharmaceuticals had to be pulled from the market or labeled with strict usage warnings due to adverse cardiac effects. In order to protect clinical trial participants and patients, the International Conference on Harmonization published guidelines to recommend that all new drugs to be tested preclinically for hERG (Kv11.1) channel sensitivity before submitting for regulatory reviews. However, extensive studies have demonstrated that measurement of hERG activity has limitations due to the multiple molecular targets of drug compound through which it may mitigate or abolish a potential arrhythmia, and therefore, a model measuring multiple ion channel effects is likely to be more predictive. Several phenotypic rapid-throughput methods have been developed to predict the potential cardiac toxic compounds in the early stages of drug development using embryonic stem cells- or human induced pluripotent stem cell-derived cardiomyocytes. These rapid-throughput methods include microelectrode array-based field potential assay, impedance-based or Ca(2+) dynamics-based cardiomyocytes contractility assays. This review aims to discuss advantages and limitations of these phenotypic assays for cardiac toxicity assessment.

The beginnings of long QT syndrome

PURPOSE OF REVIEW

The purpose of this study is to update the perinatal cardiologist and obstetrical care provider on the presentation and management of the fetus with long QT syndrome (LQTS).

RECENT FINDINGS

LQTS is a known cause of sudden death in childhood, adolescence and young adulthood that presents during fetal life, but is often not recognized. Torsades de pointes (TdP) ±2° atrioventricular block (AVB) are not always attributed to LQTS, although the most common LQTS rhythm, a fetal heart rate of less than third percentile for gestational age (GA), is not recognized as abnormal because it does not meet the standard obstetrical criteria for bradycardia. Early recognition and appropriate treatment can be life saving for the fetus and unsuspecting LQTS family members. Fetal rhythm phenotype and postnatal QTc can predict postnatal rhythm and suggest genotype: bradycardic fetuses usually have KCNQ1 mutation, while those with TdP and/or a postnatal QTc more than 500 ms have SCN5A, KCNH2 or uncharacterized mutations.

SUMMARY

The fetus with repeated heart rates of less than third percentile of GA and those with TdP ±2° AVB are likely to manifest the same rhythm after birth and have an LQTS mutation.

Prediction of fetal outcome without intrauterine intervention using a cardiovascular profile score: a systematic review and meta-analysis

OBJECTIVE

With the help of fetal echocardiography, cardiovascular profile score (CVPS) can be evaluated. However, no general agreement has been recognized on the prediction value of CVPS on fetal adverse outcome.

METHODS

Literature review has identified up to Nov 2012 in the databases. Meta-analysis was performed in a fixed/random-effect model using Revman 5.1.1 and Meta-disc 1.4. The differences among different cut-offs were measured by STATA 11.0.

RESULTS

Result from seven studies reported an outcome in favor of significant lower CVPS in fetus of adverse outcome with std. mean difference of -1.17 (95% CI = -1.78, -0.55). The overall performance of CVPS ≤ 6 prediction adverse outcome evaluated as area under the summary receiver operating characteristic curves (AUC) was 0.8777. The AUC of CVPS ≤ 7 was 0.8728 and the AUC of CVPS ≤ 8 was 0.7207. However, the result indicated the performance of CVPS ≤ 6 prediction adverse outcome had a statistical significance comparing to other two cut-offs.

CONCLUSION

Analysis has proven the CVPS is a credible index for predicting fetal adverse outcome. And once CVPS decreased at eight, the patient should be observed carefully. With the CVPS dropped at seven, treatment is demanded immediately while some cases suffer irreversible cardiac dysfunction.

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.

Doppler echocardiographic isovolumetric time intervals in diagnosis of fetal blocked atrial bigeminy and 2:1 atrioventricular block

OBJECTIVE

To distinguish between blocked atrial bigeminy (BB) and incomplete atrioventricular block with 2:1 conduction (2:1 AVB) can be very difficult, especially in the mid-term fetus. Making a correct diagnosis has important clinical implications, as their prognosis and management differ markedly. Our objective was to investigate whether analysis of isovolumetric time intervals could improve Doppler echocardiography in differentiating these conditions.

METHODS

Sixteen fetuses with sustained BB or isolated 2:1 AVB, diagnosed at our tertiary center from 2002 to 2012, were reviewed retrospectively. Doppler recordings of left ventricular in- and outflow, including mitral and aortic valve movements, were used to measure isovolumetric contraction (ICT) and relaxation (IRT) time intervals. ICT reference values obtained from 104 normal pregnancies were used for comparison.

RESULTS

Ten fetuses had BB and six 2:1 AVB. Five of the AVB cases were anti-Ro antibody positive and one had long QT syndrome (LQTS). ICT was systematically shorter in BB than in antibody-mediated 2:1 AVB. Nine of 10 cases with BB had an ICT below -2 SD and the five with antibody-mediated 2:1 AVB had values at or above +2 SD. All 15 fetuses with either BB or antibody-mediated AVB had an IRT of < 70 ms, as opposed to a markedly prolonged IRT (105 ms) in the LQTS case.

CONCLUSION

Measurement of ICT can improve the differential diagnosis between BB and antibody-mediated 2:1 AVB. Fetuses with BB or antibody-mediated AVB are unlikely to have IRT measurements exceeding 70 ms and, when this is observed, LQTS should be considered a more likely diagnosis.

Fetal long QT syndrome manifested as atrioventricular block and ventricular tachycardia: a case report and a review of the literature

Fetal onset of congenital long QT syndrome (LQTS) is a rare manifestation, and prenatal diagnosis is difficult. This report describes a boy who presented with both atrioventricular (AV) block and ventricular tachycardia during the antenatal period. The early postnatal electrocardiogram showed prolongation of the QT interval and AV block, subsequently leading to a polymorphic ventricular tachycardia torsade de pointes. This unique feature of congenital LQTS has a poor outcome, but the boy was successfully treated with beta-blockers and implantation of an automated cardioverter-defibrillator. The intrauterine manifestation of fetal AV block and ventricular tachycardia should raise a high suspicion of congenital LQTS, and the strong association with a malignant clinical course should warrant special evaluation. The literature on the prenatal diagnosis, fetal therapy, and neonatal outcome of this condition also are reviewed.

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.

In utero diagnosis of long QT syndrome by magnetocardiography

BACKGROUND

The electrophysiology of long QT syndrome (LQTS) in utero is virtually unstudied. Our goal here was to evaluate the efficacy of fetal magnetocardiography (fMCG) for diagnosis and prognosis of fetuses at risk of LQTS.

METHODS AND RESULTS

We reviewed the pre/postnatal medical records of 30 fetuses referred for fMCG because of a family history of LQTS (n=17); neonatal/childhood sudden cardiac death (n=3), or presentation of prenatal LQTS rhythms (n=12): 2° atrioventricular block, ventricular tachycardia, heart rate < 3(rd) percentile. We evaluated heart rate and reactivity, cardiac time intervals, T-wave characteristics, and initiation/termination of Torsade de Pointes, and compared these with neonatal ECG findings. After birth, subjects were tested for LQTS mutations. Based on accepted clinical criteria, 21 subjects (70%; 9 KCNQ1, 5 KCNH2, 2 SCN5A, 2 other, 3 untested) had LQTS. Using a threshold of corrected QT= 490 ms, fMCG accurately identified LQTS fetuses with 89% (24/27) sensitivity and 89% (8/9) specificity in 36 sessions. Four fetuses (2 KCNH2 and 2 SCN5A), all with corrected QT ≥ 620 ms, had frequent episodes of Torsade de Pointes, which were present 22-79% of the time. Although some episodes initiated with a long-short sequence, most initiations showed QRS aberrancy and a notable lack of pause dependency. T-wave alternans was strongly associated with severe LQTS phenotype.

CONCLUSIONS

Corrected QT prolongation (≥490 ms) assessed by fMCG accurately identified LQTS in utero; extreme corrected QT prolongation (≥620 ms) predicted Torsade de Pointes. FMCG can play a critical role in the diagnosis and management of fetuses at risk of LQTS.

Arrhythmia phenotype during fetal life suggests long-QT syndrome genotype: risk stratification of perinatal long-QT syndrome

BACKGROUND

Fetal arrhythmias characteristic of long QT syndrome (LQTS) include torsades de pointes (TdP) and/or 2° atrioventricular block, but sinus bradycardia, defined as fetal heart rate<3% for gestational age, is most common. We hypothesized that prenatal rhythm phenotype might predict LQTS genotype and facilitate improved risk stratification and management.

METHOD AND RESULTS

Records of subjects exhibiting fetal LQTS arrhythmias were reviewed. Fetal echocardiograms, neonatal ECG, and genetic testing were evaluated. We studied 43 subjects exhibiting fetal LQTS arrhythmias: TdP±2° atrioventricular block (group 1, n=7), isolated 2° atrioventricular block (group 2, n=4), and sinus bradycardia (group 3, n=32). Mutations in known LQTS genes were found in 95% of subjects tested. SCN5A mutations occurred in 71% of group 1, whereas 91% of subjects with KCNQ1 mutations were in group 3. Small numbers of subjects with KCNH2 mutations (n=4) were scattered in all 3 groups. Age at presentation did not differ among groups, and most subjects (n=42) were live-born with gestational ages of 37.5±2.8 weeks (mean±SD). However, those with TdP were typically delivered earlier. Prenatal treatment in group 1 terminated (n=2) or improved (n=4) TdP. The neonatal heart rate-corrected QT interval (mean±SE) of group 1 (664.7±24.9) was longer than neonatal heart rate-corrected QT interval in both group 2 (491.2±27.6; P=0.004) and group 3 (483.1±13.7; P<0.001). Despite medical and pacemaker therapy, postnatal cardiac arrest (n=4) or sudden death (n=1) was common among subjects with fetal/neonatal TdP.

CONCLUSIONS

Rhythm phenotypes of fetal LQTS have genotype-suggestive features that, along with heart rate-corrected QT interval duration, may risk stratify perinatal management.

Detection of T-wave alternans in fetal magnetocardiography using the generalized likelihood ratio test

T-wave alternans (TWA) is an indicator of cardiac instability and is associated with life-threatening ventricular arrhythmias. Detection of TWA in the adult has been widely investigated and is used routinely for cardiac risk assessment. Detection of TWA in the fetus, however, is much more difficult due to the low amplitude and variable configuration of the signal, the presence of strong interferences, and the brevity of fetal TWA episodes. In this paper, we present a statistical detector based on the generalized likelihood ratio test that is designed for detection of TWA in the fetus. The performance of the detector is evaluated by constructing receiver-operator characteristic curves, using simulated data and real data from subjects with macroscopic TWA. The detector is capable of detecting TWA episodes as brief as 20 beats. The detection performance is improved significantly by modeling the fetal T-wave as a low-rank, low bandwidth signal, and using maximum likelihood estimation to estimate the model parameters. This approach enables all of the data to be used to estimate the noise statistics, providing highly effective suppression of interference, including maternal interference. The method is suitable for routine use because it can be applied to raw, unprocessed recordings, allowing automated analysis of extended fetal magnetocardiography recordings.

Prenatal diagnosis of long QT syndrome with the superior vena cava-aorta Doppler approach

We describe a fetus at 36 weeks with long QT syndrome presenting with variable types of atrioventricular blocks, ventricular premature beats, and torsades de pointes. All these diagnoses were made with the superior vena cava-aorta Doppler approach and confirmed with postnatal electrocardiography.

Fetal presentation of long QT syndrome--evaluation of prenatal risk factors: a systematic review

OBJECTIVE

This systematic review evaluated the existence of risk factors for the fetal manifestation of long QT syndrome (LQTS).

METHODS

Prenatal cardiac findings suggestive of fetal LQTS were studied using 30 English literature reports extracted from the Pubmed database (1979 to December 2011) using the search terms 'long QT syndrome', 'fetal arrhythmia' and 'congenital heart disease'.

RESULTS

LQTS accounted for 15-17% of fetal bradycardias <110 bpm among fetuses with a normally structured heart. Of the patients with significant prenatal findings of LQTS, 17-35% exhibited a reduced baseline fetal heart rate (FHR) of 110-120 bpm on electronic cardiotocography. Other prenatal signs were sinus or intermittent bradycardia <110 bpm arising from atrioventricular block, tachyarrhythmias, pleural effusion and hydrops. More than 30% of Japanese infants with LQTS born at or after the mid-1980s exhibited the above-mentioned in utero signs.

CONCLUSIONS

Fetal factors including a slightly reduced baseline FHR of 110-120 bpm, bradycardia <110 bpm, tachyarrhythmias or clinical signs of heart failure, such as pleural effusion and hydrops, were associated with a higher frequency of LQTS. The use of these signs may help to increase the perinatal diagnosis of LQTS.

Developmentally regulated SCN5A splice variant potentiates dysfunction of a novel mutation associated with severe fetal arrhythmia

BACKGROUND

Congenital long-QT syndrome (LQTS) may present during fetal development and can be life-threatening. The molecular mechanism for the unusual early onset of LQTS during fetal development is unknown.

OBJECTIVE

We sought to elucidate the molecular basis for severe fetal LQTS presenting at 19 weeks' gestation, the earliest known presentation of this disease.

METHODS

Fetal magnetocardiography was used to demonstrated torsades de pointes and a prolonged rate-corrected QT interval. In vitro electrophysiological studies were performed to determine functional consequences of a novel SCN5A mutation found in the fetus.

RESULTS

The fetus presented with episodes of ventricular ectopy progressing to incessant ventricular tachycardia and hydrops fetalis. Genetic analysis disclosed a novel, de novo heterozygous mutation (L409P) and a homozygous common variant (R558 in SCN5A). In vitro electrophysiological studies demonstrated that the mutation in combination with R558 caused significant depolarized shifts in the voltage dependence of inactivation and activation, faster recovery from inactivation, and a 7-fold higher level of persistent current. When the mutation was engineered in a fetal-expressed SCN5A splice isoform, channel dysfunction was markedly potentiated. Also, R558 alone in the fetal splice isoform evoked a large persistent current, and hence both alleles were dysfunctional.

CONCLUSION

We report the earliest confirmed diagnosis of symptomatic LQTS and present evidence that mutant cardiac sodium channel dysfunction is potentiated by a developmentally regulated alternative splicing event in SCN5A. Our findings provide a plausible mechanism for the unusual severity and early onset of cardiac arrhythmia in fetal LQTS.

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.