Influence of improved antenatal detection on the outcomes of complete atrioventricular block diagnosed in fetal-neonatal life and childhood periods - a single-centre experience in South Wales for 55 years

OBJECTIVE

This study aimed to analyse the influence of improved antenatal detection on the course, contemporary outcomes, and mortality risk factors of the complete atrioventricular block during fetal-neonatal and childhood periods in South Wales.

METHODS

The clinical characteristics and outcomes of complete atrioventricular block in patients without structural heart disease at the University Hospital of Wales from January 1966 to April 2021 were studied. Patients were divided into two groups according to their age at diagnosis: I-fetal-neonatal and II-childhood. Contemporary outcomes during the post-2001 era were compared with historical data preceding fetal service development and hence earlier detection.

RESULTS

There were 64 patients: 26 were identified in the fetal-neonatal period and the remaining 38 in the childhood period. Maternal antibodies/systemic lupus erythematosus disease (anti-Ro/Sjögren's-syndrome-related Antigen A and/or anti-La/Sjögren's-syndrome-related Antigen B) were present in 15 (57.7%) of the fetal-neonatal. Fetal/neonatal and early diagnosis increased after 2001 with an incidence of 1:25000 pregnancies. Pacemaker implantation was required in 34 patients, of whom 13 were diagnosed in the fetal-neonatal group. Survival rates in cases identified before 2001 were at 96.3% (26/27), whereas it was 83.8% (31/37) in patients diagnosed after 2001 (P > 0.05). Other mortality risk factors comprised a lower gestational week at birth, maternal antibodies, and an average ventricular heart rate of < 55 bpm.

CONCLUSIONS

Fetal diagnosis of complete atrioventricular block is still portends high fetal and neonatal mortality and morbidity despite significantly improved antenatal detection after 2001. Pacemaker intervention is needed earlier in the fetal-neonatal group. Whether routine antenatal medical treatment might alter this outcome calls for further prospective multicentre studies.

Fetal Heart Rate < 3rd Percentile for Gestational Age Can Be a Marker of Inherited Arrhythmia Syndromes

BACKGROUND

Repeated fetal heart rates (FHR) < 3rd percentile for gestational age (GA) with 1:1 atrioventricular conduction (sinus bradycardia) can be a marker for long QT syndrome. We hypothesized that other inherited arrhythmia syndromes might present with fetal sinus bradycardia.

METHODS

We reviewed pregnancies referred with sinus bradycardia to the Colorado Fetal Care Center between 2013 and 2023. FHR/GA data, family history, medication exposure, normalized isovolumic contraction times (n-IVRT), postnatal genetic testing, and ECGs at 4-6 weeks after birth were reviewed.

RESULTS

Twenty-nine bradycardic subjects were evaluated by fetal echocardiography. Five were lost to follow-up, one refused genetic testing, and one had negative genetic testing for any inherited arrhythmia. Six had non-genetic causes of fetal bradycardia with normal prenatal n-IVRT and postnatal QTc. Thirteen carried pathogenic variants in RYR2 (n = 2), HCN4 (n = 2), KCNQ1 (6), and other LQTS genes (n = 4). The postnatal QTc was <470 ms in subjects with RYR2, HCN4, and two of those with KCNQ1 mutations, and >470 ms in subjects with CALM 2, KCNH2, SCN5A, and four of those with KCNQ1 mutations. LQTS and RYR2 mutations were associated with prolonged n-IVRT, but HCN4 was not. Two fetuses died in utero with variants of uncertain significance (CACNA1 and KCNE1). Cascade testing uncovered six affected but undiagnosed parents and confirmed familial inheritance in five.

CONCLUSION

In addition to heralding LQTS, repeated FHR < 3rd percentile for GA is a risk factor for other inherited arrhythmia syndromes. These findings suggest that genetic testing should be offered to infants with a history of FHR < 3rd percentile for GA even if the postnatal ECG demonstrates a normal QTc interval.

Fetal Congenital Complete Heart Block: A Rare Case with an Extremely Low Ventricular Rate and Review of Current Management Strategies

Congenital complete heart block (CCHB) is associated with high intrauterine and post-natal mortality. Prenatal detection and management, as well as appropriate delivery planning, may improve the outcomes in CCHB. We describe a rare case of CCHB that initially presented with fetal ascites and high-grade second-degree heart block noted on fetal echocardiography. The mother was noted to be positive for anti-SSA antibodies, and treatment with maternal steroids was started in an effort to reverse the fetal cardiac conduction abnormality. However, the fetal cardiac rhythm progressed to complete heart block by the follow up evaluation and the fetus had a continual declination of heart rate throughout the pregnancy to a low fetal heart rate of 25 beats per minute (bpm). This case demonstrates the lowest fetal ventricular rate documented in the literature and illustrates a severe presentation of a rare disease process. An overview of the existing knowledge related to etiology, prenatal evaluation with fetal echocardiography and fetal magnetocardiography, prenatal management, and delivery planning in fetuses with prenatally detected CCHB is included.

Diagnosis and Management of Uterine Rupture in the Third Trimester of Pregnancy: A Case Series and Literature Review

BACKGROUND

 Uterine rupture is associated with clinically significant uterine bleeding, fetal distress, expulsion or protrusion of the fetus, placenta or both into the abdominal cavity requiring prompt cesarean delivery and uterine repair or hysterectomy. Previous cesarean section is the most common risk factor. The most consistent early indicator of it is the onset of prolonged and profound fetal bradycardia.

OBJECTIVE

In this study, we present six cases of uterine rupture highlighting risk factors, and challenges in diagnosis and management, along with a review of the literature.

METHOD

A retrospective case series identified eight cases during the five-year study period. All cases from January 1, 2018 to December 31, 2022 were reviewed. Cases with multiple previous cesarean sections were excluded.

RESULT

Six cases meeting the study criteria were included in our case series. Uterine rupture was a rare occurrence with a prevalence of nine in 31,315 births representing 0.03% of deliveries. No maternal mortality or need for hysterectomy occurred in our study. Fifty percent of uterine ruptures were associated with stillbirths. The most common risk factor was a previous cesarean section in 83.3%. The most common presenting sign was non-reassuring fetal status patterns in 66.6%. A single case had a silent rupture.

CONCLUSION

Signs and symptoms of uterine rupture are nonspecific making diagnosis challenging. Delay in definitive management causes significant fetal morbidity and mortality. For best outcomes, vaginal birth after a previous cesarean section needs close monitoring in appropriately prepared units with the ability to perform immediate cesarean delivery and provide advanced neonatal support.

Optimizing the management of acute, prolonged decelerations and fetal bradycardia based on the understanding of fetal pathophysiology

Any acute and profound reduction in fetal oxygenation increases the risk of anaerobic metabolism in the fetal myocardium and, hence, the risk of lactic acidosis. On the contrary, in a gradually evolving hypoxic stress, there is sufficient time to mount a catecholamine-mediated increase in the fetal heart rate to increase the cardiac output and redistribute oxygenated blood to maintain an aerobic metabolism in the fetal central organs. When the hypoxic stress is sudden, profound, and sustained, it is not possible to continue to maintain central organ perfusion by peripheral vasoconstriction and centralization. In case of acute deprivation of oxygen, the immediate chemoreflex response via the vagus nerve helps reduce fetal myocardial workload by a sudden drop of the baseline fetal heart rate. If this drop in the fetal heart rate continues for >2 minutes (American College of Obstetricians and Gynecologists' guideline) or 3 minutes (National Institute for Health and Care Excellence or physiological guideline), it is termed a prolonged deceleration, which occurs because of myocardial hypoxia, after the initial chemoreflex. The revised International Federation of Gynecology and Obstetrics guideline (2015) considers the prolonged deceleration to be a "pathologic" feature after 5 minutes. Acute intrapartum accidents (placental abruption, umbilical cord prolapse, and uterine rupture) should be excluded immediately, and if they are present, an urgent birth should be accomplished. If a reversible cause is found (maternal hypotension, uterine hypertonus or hyperstimulation, and sustained umbilical cord compression), immediate conservative measures (also called intrauterine fetal resuscitation) should be undertaken to reverse the underlying cause. In reversible causes of acute hypoxia, if the fetal heart rate variability is normal before the onset of deceleration, and normal within the first 3 minutes of the prolonged deceleration, then there is an increased likelihood of recovery of the fetal heart rate to its antecedent baseline within 9 minutes with the reversal of the underlying cause of acute and profound reduction in fetal oxygenation. The continuation of the prolonged deceleration for >10 minutes is termed "terminal bradycardia," and this increases the risk of hypoxic-ischemic injury to the deep gray matter of the brain (the thalami and the basal ganglia), predisposing to dyskinetic cerebral palsy. Therefore, any acute fetal hypoxia, which manifests as a prolonged deceleration on the fetal heart rate tracing, should be considered an intrapartum emergency requiring an immediate intervention to optimize perinatal outcome. In uterine hypertonus or hyperstimulation, if the prolonged deceleration persists despite stopping the uterotonic agent, then acute tocolysis is recommended to rapidly restore fetal oxygenation. Regular clinical audit of the management of acute hypoxia, including the "the onset of bradycardia to delivery interval," may help identify organizational and system issues, which may contribute to poor perinatal outcomes.

Abnormal fetal heart rate patterns caused by pathophysiologic processes other than fetal acidemia

Fetal acidemia is a common final pathway to fetal death, and in many cases, to fetal central nervous system injury. However, certain fetal pathophysiological processes are associated with significant category II or category III fetal heart rate changes before the development of or in the absence of fetal acidemia. The most frequent of these processes include fetal infection and/or inflammation, anemia, fetal congenital heart disease, and fetal central nervous system injury. In the presence of significant category II or category III fetal heart rate patterns, clinicians should consider the possibility of the aforementioned fetal processes depending on the clinical circumstances. The common characteristic of these pathophysiological processes is that their associated fetal heart rate patterns are linked to increased adverse neonatal outcomes despite the absence of acidemia at birth. Therefore, in these cases, the fetal heart rate patterns may provide more insight about the fetal condition and pathophysiology than the acid-base status at birth. In addition, as successful timing of intrapartum interventions on the basis of evolution of fetal heart rate patterns aims to prevent fetal acidemia, it may not be logical to continue to use the fetal acid-base status at birth as the gold standard outcome to determine the predictive ability of category II or III fetal heart rate patterns. A more reasonable approach may be to use the umbilical cord blood acid-base status at birth as the gold standard for determining the appropriateness of the timing of our interventions.

Acute Twin-to-Twin Transfusion Syndrome Resulting in Fetal Bradycardia and Neonatal Death: A Case Report

In monochorionic twins with no evidence of chronic twin-to-twin transfusion syndrome or twin anemia-polycythemia sequence, a sudden onset of fetal transfusion syndrome after the second trimester of pregnancy is defined as acute twin-to-twin transfusion syndrome. Labor pain, change in the fetal position, and birth order are known risk factors for this condition, and the hemoglobin level of the donor twin is usually reported to be <12 g/dL. We report a recent case of acute twin-to-twin transfusion syndrome without effective labor pain causing cervical changes, resulting in fetal bradycardia and neonatal death after birth; however, the anemia of the donor twin was not as severe as has been reported previously in twin-to-twin transfusion syndrome cases.

Lower, Variable Intrathecal Opioid Doses, and the Incidence of Prolonged Fetal Heart Rate Decelerations After Combined Spinal Epidural Analgesia for Labor: A Quality Improvement Analysis

Background

Combined spinal-epidurals with low-dose intrathecal opioids and local anesthetics are commonly used to initiate labor analgesia due to the fast onset of analgesia and good patient satisfaction. Intrathecal fentanyl has been associated with fetal bradycardia, and the rate may be higher at doses of 25 mcg and above. As such, our institution limits intrathecal fentanyl doses to less than 15 mcg for labor. Prompted by a few incidents of prolonged fetal bradycardia at even these low doses, we sought to audit the side effects associated with varying low doses of intrathecal fentanyl.

Methods

After IRB approval, a retrospective review was performed on 555 labor records from May–December, 2016. All the patients received combined spinal epidurals for labor analgesia. Intrathecal medication consisted of 1 mL of 0.25% bupivacaine, and varying fentanyl doses: 2.5, 5, 10, and 15 mcg. The incidences of prolonged fetal heart rate decelerations, emergent cesarean delivery, magnitude of pain reduction, pruritus requiring treatment, and hypotension were compared.

Results

Demographic variables were equivalent between the groups. There were no differences in the rates of prolonged fetal decelerations (in order of increasing fentanyl dose: 4.4%, 2.3%, 7.6%, 3.0%, p-value = 0.11), emergent cesarean delivery, magnitude of pain reduction, pruritus, or maternal hypotension.

Conclusions

In conclusion, the rates of prolonged fetal heart rate decelerations after combined spinal epidural with intrathecal bupivacaine and fentanyl does not differ for fentanyl doses of 15 mcg and below.

Maternal hypothermia from environmental exposure in the third trimester

A primigravida at 32 weeks gestation developed hypothermia after prolonged exposure to the elements at -30.0°C. Her core temperature dropped to 29.8°C with associated foetal bradycardia. Passive rewarming was undertaken with forced warm air blankets and warmed IV fluids. The foetal heart rate normalised once normothermia was achieved. Serial foetal assessments showed appropriate growth and normal Doppler studies. She went to on deliver a healthy term infant. This case highlights conservative management and prioritising of maternal well-being with a good maternal and foetal outcome.

Fetal diagnosis of KCNQ1-variant long QT syndrome using fetal echocardiography and magnetocardiography

A pregnant woman with KCNQ1 variant long QT syndrome (LQTS) underwent fetal magnetocardiography (fMCG) after atrioventricular (AV) block was noted during fetal echocardiogram-atypical for LQTS type 1. Concern for fetal LQTS on fMCG prompted monitoring of maternal labs, change of maternal beta blocker therapy, and frequent fetal echocardiograms. Collaboration between obstetricians, neonatologists, and pediatric cardiologists ensured safe delivery. Beta blocker therapy was initiated after birth, and postnatal evaluation confirmed genotype and phenotype positive LQTS in the infant. Our experience suggests diagnosis and evaluation of fetal LQTS can alter antenatal management to reduce risk of poor fetal and postnatal outcomes.

Fetal Sinus Bradycardia Is Associated with Congenital Hypothyroidism: An Infant with Ectopic Thyroid Tissue

Hypothyroidism is rarely included in the differential diagnosis for fetal sinus bradycardia. We report an infant with congenital hypothyroidism caused by ectopic thyroid tissue, who showed antenatal bradycardia. The baseline fetal heart rate was 100-110 bpm at 30 weeks of gestation, and fetal echocardiography revealed sinus bradycardia but no cardiac anomalies. Maternal thyroid function was normal (thyroid-stimulating hormone [TSH] 2.03 μIU/ml, free T3 2.65 pg/ml, and free T4 0.99 ng/dl) when measured at 31 weeks of gestation. Her serum anti SS-A and SS-B antibodies, anti-thyroglobulin, and microsomal antibodies were negative. A male infant without cardiac anomalies was delivered at 35 weeks and 4 days of gestation and admitted for prematurity and respiratory distress syndrome. The infant's heart rate was 70-110 bpm (normal: 120-160 bpm) on admission. On 8 days of age, thyroid function tests revealed that the infant had severe hypothyroidism (TSH 903.3 μIU/ml, free T3 1.05 pg/ml, and free T4 0.26 ng/dl). The prolonged jaundice assumed to be due to hypothyroidism. Oral levothyroxine sodium hydrate (10 μg/kg/day) was immediately started on day 8. After the treatment, the heart rate was gradually increased to 130-140 bpm as the infant's thyroid function was improved (TSH 79.8 μIU/ml, free T3 2.95 pg/dl, and free T4 1.66 ng/dl on day 22). The infant was diagnosed ectopic thyroid tissue because of the high thyroglobulin level (85.9 μg/l). In conclusion, congenital hypothyroidism should be included in the differential diagnosis in cases of fetal bradycardia without cardiac anomalies or maternal autoimmune diseases.

Uterine hypertonus and fetal bradycardia occurred after combined spinal-epidural analgesia during induction of labor with oxytocin infusion: A case report

RATIONALE

Pain management is an essential part of good obstetrical care. The rapid onset of pain relief after combined spinal-epidural (CSE) analgesia may cause a transient imbalance in maternal catecholamine level, leading to uterine hyperactivity and fetal heart rate (FHR) abnormalities. How to manage the uterine basal tone and FHR abnormalities after labor analgesia still remains controversial.

PATIENT CONCERNS

A 33-year-old nulliparous woman at 40 weeks' gestation underwent induction of labor after premature rupture of membranes. CSE analgesia was provided when the patient described her pain as the top on a scale of 10 during induction of labor with oxytocin infusion.

DIAGNOSES

Uterine hypertonus and fetal bradycardia were diagnosed within 10 minutes after CSE analgesia.

INTERVENTIONS

Oxytocin infusion and CSE analgesia were immediately suspended, and measures of staying in left lateral decubitus position and giving supplemental oxygen were attempted to resuscitating the baby. Because of suspicious fetal distress, the baby was rapidly delivered by emergency cesarean section.

OUTCOMES

The Apgar score of the baby was 8 and 10 at 1 and 5 minutes after birth. Subsequent follow-up confirmed that both mother and baby were in good condition.

LESSONS

The loss of the tocolytic effect of epinephrine after CSE analgesia and continuous oxytocin infusion may work together to form a totally synergistic function, finally leading to inevitable uterine hypertonus and fetal bradycardia. Both the obstetrical provider and anesthesiologist should carefully monitor all patients in the first 15 minutes after CES analgesia induction. Oxytocin administration in this critical period deserves attention. Additionally, intraprofessional collaboration is also necessary to ensure high quality and safe delivery for all childbearing women.

Challenges in the diagnosis and management of isolated congenital complete atrioventricular block in premature newborns

Diagnostic and treatment challenges of congenital complete atrioventricular block in two premature newborn babies are presented. Timely recognition of this fetal condition, appropriate antenatal care, and treatment at a tertiary level care hospital as well as prompt postnatal management of the newborn baby are the key factors for good outcome. Prematurity is also associated with an additional risk of poor outcome and complications.

Intrapartum fetal heart rate patterns preceding terminal bradycardia in infants (>34 weeks) with poor neurological outcome: A regional population-based study in Japan

AIM

Intrapartum fetal bradycardia necessitates immediate operative delivery. Our aim was to investigate the hypothesis that some non-reassuring fetal heart rate (FHR) patterns were present before the onset of terminal bradycardia in infants who developed subsequent brain damage.

MATERIAL AND METHODS

From a population-based study of 65,197 deliveries, 190 stillbirths, 115 neonatal deaths, and 136 neurologically high-risk infants were registered by the Miyazaki Perinatal Conference. There were 15 cases of neurologically high-risk infants born at >34 weeks of gestation exhibiting intrapartum terminal bradycardia. Focusing on the brain-damaged infants, we retrospectively analyzed FHR patterns for at least 1 h prior to the bradycardia.

RESULTS

Brain damage (cerebral palsy [n = 11] and mental retardation [n = 2]) was diagnosed at 2 years old in 13 out of 15 neurologically high-risk infants. Two infants had bradycardia on admission. In the remaining 11 infants, FHR patterns were reassuring in six (55%) and non-reassuring in five (45%), including late decelerations (n = 4) and variable decelerations (n = 2). Clinically relevant factors in the non-reassuring group included intrauterine infection (n = 3), malpresentation with umbilical cord coiling (n = 1), and unknown causes (n = 1). Clinically relevant features in the reassuring group included cord prolapse (n = 1), vaginal breech delivery (n = 1), shoulder dystocia (n = 1), rupture of membranes (n = 1), and unknown causes (n = 2).

CONCLUSION

More than half of the brain-damaged infants born at >34 weeks of gestation who exhibited intrapartum terminal bradycardia had unremarkable FHR patterns before abrupt-onset bradycardia. For those with non-reassuring patterns preceding bradycardia, intrauterine infection was the major sentinel event.

Overview of fetal arrhythmias

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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