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.

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.

The cumulative incidence of neonatal metabolic acidemia after terminal bradycardia in the 2nd stage of labor: a survival-based model.

PURPOSE: The aim of the study was to estimate by a survival analysis model the hazard function (HF) for neonatal metabolic acidemia (MA) throughout the 2nd stage of labor (2STG) at the time of occurrence of a terminal bradycardia ≥ 10 min requiring expedited delivery, and the cumulative incidence function (CIF) for MA according with the duration of bradycardia stratified in 10-12 min and > 12 min. METHODS: Singleton pregnancies experiencing terminal fetal bradycardia requiring expedited delivery in the 2STG at 38 + 0-41 + 3 weeks and delivering in the year 2019, were identified. The presence of MA (pH < 7 and/or BE ≤ - 12 mmol/L) was determined based on the acid-base status in the umbilical artery cord blood. Survival analysis was used to assess the hazard function (HF) and the cumulative incidence function (CIF) for MA occurring after terminal fetal bradycardia, at the 2STG. RESULTS: Out of a non-consecutive population of 12,331 pregnancies, there were 52 cases that fit the inclusion criteria. Twenty-four (46.2%) of those develop MA. Abnormal quantitative pH values and the HF for MA correlated with the duration of 2STG at the time of bradycardia onset, but not with bradycardia duration. After 60 min of duration of 2STG, the HF (or instantaneous rate of failure) increased dramatically (from 1.2 to 20 about at 120 min). At paired duration of 2STG, a higher CIF was observed for the terminal bradycardia > 12 min. CONCLUSION: Forty-six percent of term fetuses with terminal bradycardia had MA at birth. Despite the low sensitivity and a non-significant association with quantitative pH values, the duration of terminal bradycardia in the 2STG is associated with a higher CIF for MA.

Fetal heart rate tracings associated with eclamptic seizures.

BACKGROUND: Although there is a well-known association between fetal bradycardia and maternal eclampsia, the characteristics of fetal heart rate tracings after an eclamptic seizure have not previously been thoroughly described. Fetal heart rate changes are thought to be related to maternal lactic acidemia caused by vasospasm and uterine hyperactivity leading to placental hypoperfusion and fetal hypoxia. The decision to intervene in the case of an abnormal fetal heart rate tracing after an eclamptic seizure is often difficult; however, maternal resuscitation should be the primary focus. OBJECTIVE: This study aimed to quantify and characterize fetal heart rate changes associated with a maternal eclamptic seizure. Moreover, we sought to document subsequent obstetrical management following these seizures complicated by fetal heart rate decelerations. STUDY DESIGN: This was a retrospective study of fetal heart rate tracings associated with eclampsia during a 13-year period at a single institution. Eclampsia was diagnosed following the 2013 Executive Summary of the American College of Obstetricians and Gynecologists criteria. Tracings were independently reviewed and classified by 3 physicians using the National Institute of Child Health and Human Development Criteria. Hospital records were reviewed to ascertain obstetrical management after the eclamptic seizure. RESULTS: A total of 107 women were diagnosed with eclampsia from January 2009 to December 2021. Of these women, 31 experienced 34 intrapartum seizures during which time electronic fetal heart rate monitoring was ongoing. During the 34 seizures, fetal heart rate decelerations were documented in 79% of cases. The mean duration of bradycardia was 5.80±2.98 minutes with a range of 2 to 15 minutes. Fetal heart decelerations occurred, on average, 2.7±1.6 minutes after the onset of the eclamptic seizure. In half of the fetuses with fetal heart rate changes, fetal tachycardia followed, and in 48% of cases, there was minimal variability noted. As a result of the fetal heart rate tracings and clinical findings, 4 women underwent an emergent cesarean delivery, including 2 that were diagnosed with placental abruption. In this cohort, there were 4 cases of abruption. The mean duration from the seizure to delivery was 299±353 minutes. The mean neonatal cord pH was 7.20±0.11 with a mean base excess of -8.6±4.4 mmol/L. There was no perinatal death. CONCLUSION: After an eclamptic seizure, 79% of fetuses demonstrated prolonged decelerations, and half of the fetuses developed fetal tachycardia after recovery from the episode of bradycardia. Despite these periods of fetal heart rate decelerations associated with eclampsia, prioritization of maternal support and stabilization resulted in a favorable perinatal outcome without immediate operative intervention in more than two-thirds of cases.

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.

Bradycardia-to-delivery interval and fetal outcomes in umbilical cord prolapse.

INTRODUCTION: Umbilical cord prolapse is a major obstetric emergency associated with significant perinatal complications. However, there is no consensus on the optimal decision-to-delivery interval, as many previous studies have shown poor correlation between the interval and umbilical cord arterial blood gas or perinatal outcomes. We aim to investigate whether bradycardia-to-delivery or decision-to-delivery interval was related to poor cord arterial pH or adverse perinatal outcome in umbilical cord prolapse. MATERIAL AND METHODS: This was a retrospective study conducted at a university tertiary obstetric unit in Hong Kong. All women with singleton pregnancy complicated by cord prolapse during labor between 1995 and 2018 were included. Women were categorized into three groups. Group 1: persistent bradycardia; Group 2: any type of decelerations without bradycardia; and Group 3: normal fetal heart rate. The main outcome was cord arterial blood gas results of the newborns in different groups. Maternal demographic data and perinatal outcomes were reviewed. Correlation analysis between cord arterial blood gas result and time intervals including bradycardia-to-delivery, deceleration-to-delivery, and decision-to-delivery were performed for the different groups with Spearman test. RESULTS: There were 34, 30, and 50 women in Groups 1, 2, and 3, respectively. Cord arterial pH and base excess did not correlate with decision-to-delivery interval in any of the groups, but they were inversely correlated with bradycardia-to-delivery interval in Group 1 (Spearman's ρ = -.349; P = .043 and Spearman's ρ = -.558; P = .001, respectively). The cord arterial pH drops at 0.009 per minute with bradycardia-to-delivery interval in Group 1 (95% CI 0.0180-0.0003). The risk of significant acidosis (pH < 7) was 80% when bradycardia-to-delivery interval was >20 minutes, and 17.2% when the interval was <20 minutes. CONCLUSIONS: There is significant correlation between bradycardia-to-delivery interval and cord arterial pH in umbilical cord prolapse with fetal bradycardia but not in cases with decelerations or normal heart rate. The drop of cord arterial pH is rapid and urgent delivery is essential in such situations.

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.

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.

Fetal bradycardia and acidosis during maternal parenteral iron: Case reports and literature review.

Iron deficiency anemia is an important problem among pregnant women, and intravenous (IV) iron infusions have been increasingly used. Whether fetal monitoring is required during infusion has been debated, with a recent guideline by Hematologists recommending against such. We report two cases of fetal bradycardia after iron isomaltoside (IIM), in women with otherwise good maternal and fetal health. Both developed dyspnea with desaturation minutes from infusion, followed by persistent fetal bradycardia. Both underwent category 1 CS, with cord arterial pH of 7.08 and 6.94 respectively. Upon literature review, only three case reports on fetal bradycardia in IV iron were identified. For older IV iron formulations, a case was reported after IV dextran test dose, while two cases after ferric gluconate were reported. For the new formulation IIM, only one case was reported so far, but in a woman with Crohn's disease and intrauterine growth restriction. IV iron in pregnancy carries risk of anaphylactic or hypersensitivity reactions, even with the newest formulations and in women with good maternal and fetal health. While rarely reported so far, fetal bradycardia is a possible consequence, commonly preceded by respiratory symptoms. Fetal monitoring should therefore be considered during infusion.

How cold is too cold during maternal sepsis? Navigating between maternal hypothermia and fetal bradycardia.

Hypothermia is a relatively rare condition in pregnancy and has been associated with fetal bradycardia. The management of maternal hypothermia resulting in fetal bradycardia presents a challenging dilemma for healthcare professionals. Currently, no evidence exists to advise on the duration of this condition before obstetric interventions are necessary for a safe outcome for both mother and infant. We discuss a case of a 26-year old primigravida with a gestational age of 32 weeks, who presented with clinical urosepsis, resulting in severe hypothermia up to 32 degrees Celsius. Active warming measures were taken and intravenous antibiotic treatment was started. Fetal evaluation on the cardiotocogram showed prolonged bradycardia (90 BPM) prompting consideration of a cesarean section. However, after multidisciplinary consultation, conservative treatment was proposed since there were no other signs of fetal hypoxia; no decelerations, good variability and accelerations. The patient started to show clinical improvement and had a body core temperature of 36 degrees Celsius after approximately 60 h of active rewarming measures. Fetal heartrate baseline normalized as the maternal temperature raised. Subsequently the patient was discharged in good clinical condition and had an uncomplicated vaginal delivery of a healthy newborn at term. In conclusion, when fetal bradycardia occurs due to maternal hypothermia, in the absence of signs for fetal hypoxia on the cardiotocogram, treatment of the underlying maternal condition instead of immediate obstetrics intervention is the best clinical option. This strategy aims to address the underlying cause of maternal hypothermia and consequently fetal bradycardia while ensuring the well-being of both mother and fetus and preventing unnecessary premature delivery.

Uterine sacrifice in obstetric emergencies case series: Complex cases of fetal distress, labor challenges, and life-saving interventions.

This study highlights the complexities and challenges in managing obstetric emergencies, detailing critical interventions and outcomes in various high-risk cases. A retrospective analysis was conducted on four high-risk obstetric cases, each characterized by distinct complications necessitating immediate medical interventions. The study specifically examined cases involving: Fetal Distress cases where fetal health was compromised, necessitating interventions such as emergency cesarean sections. Complex Labor Dynamics detailed examinations of labor complications such as obstructed labor, precipitate labor, or labor complicated by malpresentation. Early pregnancy complications analysis focused on emergencies arising in the first trimester or early second trimester, including ectopic pregnancies and complications in pregnancies with a history of multiple cesarean sections. Severe postpartum hemorrhage investigations into cases of significant blood loss post-delivery, which required interventions ranging from pharmacological management to surgical procedures like hysterectomy. The first case concerned a 28-year-old primigravida with fetal bradycardia and thick meconium, requiring an emergency cesarean section. Postoperative complications included gestational thrombocytopenia and anemia, necessitating a total abdominal hysterectomy for severe sepsis. The newborn showed good recovery, indicated by Apgar scores. In Case 2, the need for a hysterectomy following complications during the third stage of labor was likely due to the presence of Placenta Accreta Spectrum, specifically placenta accreta or increta. While a retained placenta typically can be managed with less invasive methods, the situation escalates when the placenta is abnormally adherent to, or deeply invasive into, the uterine muscle. This can lead to uncontrollable bleeding, making a hysterectomy necessary and justified as a life-saving measure to control the severe hemorrhage while the histology confirms the diagnosis for the placenta accreta. In the third case, the decision to perform a dilation and curettage over manual vacuum aspiration was influenced by several factors. Given the severity of the patient's hemorrhage and the presence of a suspicious echogenic structure, a dilation and curettage provided a more controlled environment for thorough evacuation and immediate bleeding control. This approach was also supported by the combination technique using both Karman aspiration and a curette, allowing for effective management of complicated cases, particularly in patients with a history of multiple cesareans and potential scar tissue. The fourth case involved a 37-year-old multipara with severe postpartum hemorrhage from uterine atony, treated with surgery and managed for diabetic ketoacidosis, leading to discharge on the fourth day. This underscores the urgency and complexity of managing obstetric emergencies effectively.

Diagnosis and Management of Fetal Arrhythmias in the Current Era.

Diagnosis and management of fetal arrhythmias have changed over the past 40-50 years since propranolol was first used to treat fetal tachycardia in 1975 and when first attempts were made at in utero pacing for complete heart block in 1986. Ongoing clinical trials, including the FAST therapy trial for fetal tachycardia and the STOP-BLOQ trial for anti-Ro-mediated fetal heart block, are working to improve diagnosis and management of fetal arrhythmias for both mother and fetus. We are also learning more about how "silent arrhythmias", like long QT syndrome and other inherited channelopathies, may be identified by recognizing "subtle" abnormalities in fetal heart rate, and while echocardiography yet remains the primary tool for diagnosing fetal arrhythmias, research efforts continue to advance the clinical envelope for fetal electrocardiography and fetal magnetocardiography. Pharmacologic management of fetal arrhythmias remains one of the most successful achievements of fetal intervention. Patience, vigilance, and multidisciplinary collaboration are key to successful diagnosis and treatment.

An Unusual Presentation of an Amniotic Fluid Embolism: Fetal Bradycardia As the First Sign.

Amniotic fluid embolism (AFE) is a potentially fatal maternal condition demanding awareness from obstetricians and anesthesiologists regarding its different manifestations. The typical presentation involves maternal respiratory distress, cardiovascular collapse, neurological changes, and coagulopathy followed by fetal distress. This unusual case study emphasizes that fetal compromise may precede maternal decompensation as the initial sign of AFE. Fetal distress is a known symptom of AFE and is typically seen due to cardiorespiratory issues that lead to reduced uteroplacental perfusion, resulting in fetal hypoxia. In the case presented, fetal bradycardia occurred before any visible maternal symptoms, suggesting that fetal distress could be induced by factors independent of the mother's cardiopulmonary status. A 34-year-old healthy G4P2012 at 41 weeks and 2 days gestation who was initially laboring on the floor was emergently taken to the operating room for a cesarean delivery due to fetal bradycardia. Around the time the fetus was delivered, the patient displayed seizure activity, followed by a complete loss of consciousness and cardiac arrest. The patient was intubated and underwent cardiopulmonary resuscitation and defibrillation, subsequently converting to a wide complex tachycardia. In the operating room, there was evidence of heavy vaginal bleeding, uterine atony, and a fulminant form of disseminated intravascular coagulopathy (DIC), which required aggressive management over the next four hours. After achieving hemodynamic stability, the patient was transferred to the surgical intensive care unit (SICU), extubated on day 3, and discharged home on day 8.

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.