Guidelines for the interpretation of the neonatal electrocardiogram. A task force of the European Society of Cardiology

Fifteen-minute consultation: How to manage neonatal bradycardia

Neonatal bradycardia is characterised by a heart rate below 80 bpm, irrespective of gestational age. It is generally self-resolving but, in some cases, represents an underlying pathology which may be cardiac or non-cardiac in origin. The common causes for bradycardia are non-cardiac in origin such as autonomic immaturity in premature infants, electrolyte imbalances, hypothyroidism and medications. Cardiac causes include-sinus bradycardia, conduction system abnormalities, congenital heart disease and channelopathies. Diagnostic investigations typically include a standard 12-lead ECG, 24-hour Holter monitor and an echocardiogram. This article aims to provide a practical framework for the management of neonates with bradycardia and guide further investigation and/or referral to specialist paediatric cardiology services.

Successful Pregnancy Outcome With Preconception Care in a Symptomatic Carrier of Duchenne Muscular Dystrophy: Case Report and Literature Review

Duchenne Muscular Dystrophy (DMD) is an X-linked recessive disorder. Female carriers can manifest symptoms during pregnancy, complicating diagnosis and genetic counseling before conception. This is the first report of a DMD symptomatic carrier who was managed continuously from preconception through pregnancy for symptoms recognized before conception. A 31-year-old primipara woman was incidentally noted to have premature ventricular contractions, heart failure, and elevated creatine kinase levels 2 years before pregnancy. Genetic testing confirmed that the patient was a symptomatic carrier of DMD. She had no family history of muscular or cardiac disease, suggesting a de novo variant. She received genetic counseling and planned amniocentesis during pregnancy as prenatal diagnosis. After treatment with bisoprolol and flecainide, her cardiac function improved, and natural conception was achieved. Amniocentesis performed at 16 weeks of gestation indicated a 46, XX karyotype, leading to the decision to continue the pregnancy. From week 16 to 21, the fetus exhibited bradycardia due to blocked premature atrial contraction, which later improved, although the atrioventricular interval was prolonged. The mother delivered vaginally without any complications, and the infant's atrioventricular interval normalized. Preconceptional diagnosis and treatment for DMD carrier status are crucial for shared decision-making and to achieve favorable perinatal outcomes.

Electrocardiogram screening for school children: a cross-sectional, population-based study

BACKGROUND

Identification of life-threatening arrhythmogenic disorders, which may present during infancy, childhood, or later stages, enables the early initiation of effective preventive therapies. Electrocardiogram (ECG) screening may detect conditions that elevate risk of sudden cardiac death (SCD) at an early stage.

OBJECTIVES

This study aims to assess the prevalence, clinical significance, and characteristics of ECG abnormalities in a large population of schoolchildren. It also aims to determine whether ECGs performed during childhood can aid in the early detection of conditions associated with the risk of SCD.

DESIGN

Population-based cross-sectional study.

SETTING

A multicenter study conducted at King Faisal Specialist Hospital & Research Centre (KFSHRC) in Riyadh and Prince Sultan Cardiac Center-Qassim (PSCC-Q), Qassim, Saudi Arabia.

METHODS

The study analyzed 12-lead ECGs performed on elementary school students 6-15 years old in Buraidah, Qassim region, Saudi Arabia. ECGs were recorded and interpreted following international standards. Children with abnormal ECG results were referred for full pediatric cardiology evaluation.

MAIN OUTCOME MEASURES

Prevalence of normal and abnormal ECG findings, including long QT intervals.

SAMPLE SIZE

14 403 students.

RESULTS

During the study period, ECGs were performed on 14 403 students (53.8% females). The mean age was 9.5±1.9 years, and the mean weight was 32.1±16.1 kg. Abnormal ECGs were identified in 468 students (3.3%), 271 of whom had complete clinical evaluation, including repeat ECG and echocardiography. The most common ECG abnormality was a prolonged QTc interval. The overall prevalence of abnormal ECG findings ranged from 0.7% to 2.04%, with long QTc intervals (460 msec or more) found in 0.4% to 1.6% of students.

CONCLUSIONS

Long QTc intervals (460 msec or more) were the most common ECG abnormality in school children, with an estimated prevalence of 0.4% to 1.6%. This study may serve as a model for large-scale, community-based, 12-lead ECG screening programs for children.

LIMITATIONS

Causality cannot be derived given the design, the potential for false positive and false-negative results, and the lack of genetic studies for children with prolonged QT intervals.

Validation of a Demography-Based Adaptive QT Correction Formula Using Pediatric and Adult Datasets Acquired From Humans and Guinea Pigs

BACKGROUND

QT correction (QTc) formulae are widely used in clinical and research settings but often underperform, possibly due to demographic influences on the QT-heart rate (HR) relationship. To address this limitation, we developed an adaptive QTc (QTcAd) formula, which adjusts for demographic factors like age, and compared its efficacy to other standard formulae.

METHODS

The QTcAd formula was tested across diverse age groups with different HR in both humans and guinea pigs. Using retrospective ECG data from 1819 pediatric patients at Children's National Hospital and 2400 subjects from the Pediatric Heart Network database, alongside in vivo (N=55) and ex vivo (N=66) guinea pig ECG recordings, we evaluated the formula's effectiveness. Linear regression fit parameters of QTc-HR (slope and R²) were utilized for performance assessment. To evaluate the accuracy of the predicted QTc, we acquired epicardial electrical and optical voltage data from Langendorff-perfused guinea pig hearts.

RESULTS

In both human subjects and guinea pigs, the QTcAd formula (QTcAd=QT+(|m|×(HR-HRmean)) consistently outperformed other formulae across all age groups. For instance, in a 20-year-old human group, the QTcAd formula successfully nullified the inverse QT-HR relationship (R²=5.1×10-10, slope=-3.5×10-5), whereas the Bazett formula failed to achieve comparable effectiveness (R²=0.21, slope=0.91). Moreover, the QTcAd formula exhibited better accuracy than the age-specific Benatar QTc formula, which overcorrected QTc (1-week human QT: 263.8±14.8 ms, QTcAd: 263.8±7.3 ms, P=0.62; Benatar QTc: 422.5±7.3 ms, P<0.0001). The optically measured pseudo-QT interval (143±22.5 ms, n=44) was better approximated by QTcAd (180.6±17.0 ms) compared with all other formulae. Furthermore, we demonstrated that the QTcAd formula was not inferior to individual-specific QTc formulae.

CONCLUSIONS

The demography-based QTcAd formula showed superior performance across human and guinea pig age groups, which may enhance the efficacy of rate-corrected K.M.M. for cardiovascular disease diagnosis, risk stratification, and drug safety testing in children and adults.

Maternal autoimmune systemic connective tissue disease and vasculitis and electrocardiographic findings in the offspring

INTRODUCTION

Maternal autoimmune systemic connective tissue diseases (CTDs) and their related antibodies have been associated with adverse fetal outcomes, including complete heart block. In this study, we assessed the association between maternal CTD or vasculitis and neonatal electrocardiographic (ECG) parameters.

METHODS

Our study population was drawn from the Copenhagen Baby Heart Study (CBHS), a prospective, population-based cohort study open to all neonates born in the Copenhagen area. All CBHS neonates born to mothers with CTD or vasculitis were matched 1:3 to neonates born to mothers without these diseases on sex, gestational age, age and weight at time of examination, and maternal age at delivery. Maternal CTD and vasculitis diagnoses were validated through medical record review. Our primary analyses compared ECG parameters for exposed and unexposed neonates overall. Where numbers allowed, subanalyses were then conducted by specific CTD diagnoses and autoantibody types.

RESULTS

Among 17,862 CBHS neonates with an available ECG, 40 neonates of mothers with CTDs or vasculitis (50 % males, median age 12 [interquartile range 8-16] days) were matched to unexposed neonates. Overall, no significant differences in heart rate, PR interval, QRS axis, QRS duration, QT/QTc interval, or R- or S-wave amplitudes were found when comparing exposed and unexposed neonates (all p > 0.05). Similarly, separate analyses of the 10 neonates with anti-Ro/SSA-positive mothers and their matched comparators revealed no significant between-group differences. However, neonates born to mothers with antiphospholipid syndrome (n = 15) had a significantly longer QRS duration (median 56 ms vs. 52 ms, p = 0.02) and corrected QT interval (median QTcBaz 430 ms vs. 414 ms, p = 0.01), compared with matched unexposed neonates.

CONCLUSION

In this population-based study, no significant overall differences in ECG parameters were found between neonates exposed to maternal CTD or vasculitis and unexposed neonates. However, neonates exposed to maternal antiphospholipid syndrome had significantly longer QRS- and QTc intervals than unexposed neonates. The potential clinical implications of these findings are unknown and, combined with the limitations of this study, warrant further investigation in larger cohorts.

Validation of a Demography-Based Adaptive QTc Formula using Pediatric and Adult Datasets Acquired from Humans and Guinea Pigs

Introduction

A variety of QT rate-correction (QTc) formulae have been utilized for both clinical and research purposes. However, these formulae are not universally effective, likely due to significant influences of demographic diversity on the QT-HR relationship. To address this limitation, we proposed an adaptive QTc (QTcAd) formula that adjusts to subject demographics (i.e., age). Further, we compared the efficacy and accuracy of the QTcAd formula to other widely used alternatives.

Method

Using age as a demographic parameter, we tested the QTcAd formula across diverse age groups with different heart rates (HR) in both humans and guinea pigs. Utilizing retrospective human (n=1360) and guinea pig electrocardiogram (ECG) data from in-vivo (n=55) and ex-vivo (n=66) settings, we evaluated the formula's effectiveness. Linear regression fit parameters of HR-QTc (slope and R²) were utilized for performance assessment. To evaluate the accuracy of the predicted QTc, we acquired epicardial electrical and optical voltage data from Langendorff-perfused guinea pig hearts.

Results

In both human subjects and guinea pigs, the QTcAd formula consistently outperformed other formulae across all age groups. For instance, in a 20-year-old human group (n=300), the QTcAd formula successfully nullified the inverse HR-QT relationship (R²=5.1E-09, slope=-3.5E-05), while the Bazett formula (QTcB) failed to achieve comparable effectiveness (R²= 0.20, slope=0.91). Moreover, the QTcAd formula exhibited better accuracy than the age-specific Benatar formula (QTcBe), which overcorrected QTc (1-week human QT: 263.8±14.8 ms, QTcAd: 263.8±7.3 ms, p=0.62; QTcBe: 422.5±7.3 ms, p<0.0001). The optically measured pseudo-QT interval (143±22.5 ms, n=44) was better approximated by QTcAd (180.6±17.0 ms) compared to all other formulae. Furthermore, we demonstrated that the QTcAd formula was not inferior to individual-specific QTc formulae.

Conclusion

The demography-based QTcAd formula showed superior performance across human and guinea pig age groups, which may enhance the efficacy of QTc for cardiovascular disease diagnosis, risk stratification, and drug safety testing.

What is known

Corrected QT (QTc) is a well-known ECG biomarker for cardiovascular disease risk stratification and drug safety testing. Various QT rate-correction formulae have been developed, but these formulae do not perform consistently across diverse datasets (e.g., sex, age, disease, species).

What the study adds

We introduce a novel QTc formula (QTcAd) that adapts to demographic variability, as the parameters can be modified based on the characteristics of the study population. The formula (QTcAd = QT + (|m|*(HR-HR mean )) - includes the absolute slope (m) of the linear regression of QT and heart rate (HR) and the mean HR of the population (HR mean ) as population characteristics parametersˍUsing datasets from both pediatric and adult human subjects and an animal model, we demonstrate that the QTcAd formula is more effective at eliminating the QT-HR inverse relationship, as compared to other commonly used correction formulae.

Electroanatomical adaptations in the guinea pig heart from neonatal to adulthood

AIMS

Electroanatomical adaptations during the neonatal to adult phase have not been comprehensively studied in preclinical animal models. To explore the impact of age as a biological variable on cardiac electrophysiology, we employed neonatal and adult guinea pigs, which are a recognized animal model for developmental research.

METHODS AND RESULTS

Electrocardiogram recordings were collected in vivo from anaesthetized animals. A Langendorff-perfusion system was employed for the optical assessment of action potentials and calcium transients. Optical data sets were analysed using Kairosight 3.0 software. The allometric relationship between heart weight and body weight diminishes with age, it is strongest at the neonatal stage (R2 = 0.84) and abolished in older adults (R2 = 1E-06). Neonatal hearts exhibit circular activation, while adults show prototypical elliptical shapes. Neonatal conduction velocity (40.6 ± 4.0 cm/s) is slower than adults (younger: 61.6 ± 9.3 cm/s; older: 53.6 ± 9.2 cm/s). Neonatal hearts have a longer action potential duration (APD) and exhibit regional heterogeneity (left apex; APD30: 68.6 ± 5.6 ms, left basal; APD30: 62.8 ± 3.6), which was absent in adults. With dynamic pacing, neonatal hearts exhibit a flatter APD restitution slope (APD70: 0.29 ± 0.04) compared with older adults (0.49 ± 0.04). Similar restitution characteristics are observed with extrasystolic pacing, with a flatter slope in neonates (APD70: 0.54 ± 0.1) compared with adults (younger: 0.85 ± 0.4; older: 0.95 ± 0.7). Neonatal hearts display unidirectional excitation-contraction coupling, while adults exhibit bidirectionality.

CONCLUSION

Postnatal development is characterized by transient changes in electroanatomical properties. Age-specific patterns can influence cardiac physiology, pathology, and therapies for cardiovascular diseases. Understanding heart development is crucial to evaluating therapeutic eligibility, safety, and efficacy.

Cardiac Development and Related Clinical Considerations

The anatomy, physiology, and hemodynamics of the premature heart vary along the range of gestational ages cared for in neonatal intensive care units, from 22 weeks to term gestation. Clinical management of the preterm neonate should account for this heterogenous development. This requires an understanding of the impact of ex utero stressors on immature and disorganized cardiac tissue, the different state of hemodynamics across intracardiac shunts impacting the natural transition from fetal to neonatal life, and the effects of intensive pharmacologic and non-pharmacologic interventions that have systemic consequences influencing cardiac function. This article provides a review of the increasing but still limited body of literature on the anatomy, hemodynamics, and electrophysiology of the preterm heart with relevant clinical considerations.

Early Screening for Long QT Syndrome and Cardiac Anomalies in Infants: A Comprehensive Study

(1) Background: Sudden Infant Death Syndrome (SIDS) represents sudden and unexplained deaths during the sleep of infants under one year of age, despite thorough investigation. Screening for a prolonged QTc interval, a marker for Long QT Syndrome (LQTS), should be conducted on all newborns to reduce the incidence of SIDS. Neonatal electrocardiograms (ECGs) could identify congenital heart defects (CHDs) early, especially those not detected at birth. Infants with prolonged QTc intervals typically undergo genetic analysis for Long QT Syndrome. (2) Methods: The study involved infants aged 20-40 days, born with no apparent clinical signs of heart disease, with initial ECG screening. Infants with prenatal diagnoses or signs/symptoms of CHDs identified immediately after birth, as well as infants who had previously had an ECG or echocardiogram for other medical reasons, were excluded from the study. We used statistical software (SPSS version 22.0) to analyze the data. (3) Results: Of the 42,200 infants involved, 2245 were enrolled, with 39.9% being males. Following this initial screening, 164 children (37.8% males) with prolonged QTc intervals underwent further evaluation. Out of these 164 children, 27 children were confirmed to have LQTS. However, only 18 children were finally investigated for genetic mutations, and mutations were identified in 11 tests. The most common mutations were LQT1 (54.5%), LQT2 (36.4%), and LQT3 (1 patient). Treatment options included propranolol (39.8%), nadolol (22.2%), inderal (11.1%), metoprolol (11.1%), and no treatment (16.7%). The most common abnormalities were focal right bundle branch block (54.5%), left axis deviation (9.2%), and nonspecific ventricular repolarization abnormalities (7.1%). Multiple anomalies were found in 0.47% of children with focal right bundle branch block. Structural abnormalities were associated with specific features in 267 patients (11.9%), primarily isolated patent foramen ovale (PFO) at 61.4%. (4) Conclusions: This screening approach has demonstrated effectiveness in the early identification of LQTS and other cardiac rhythm anomalies, with additional identification of mutations and/or prolonged QTc intervals in family members. Identifying other ECG abnormalities and congenital heart malformations further enhances the benefits of the screening.

Effect of parental touch on relieving acute procedural pain in neonates and parental anxiety (Petal): a multicentre, randomised controlled trial in the UK

BACKGROUND

Touch interventions such as massage and skin-to-skin contact relieve neonatal pain. The Parental touch trial (Petal) aimed to assess whether parental stroking of their baby before a clinically required heel lance, at a speed of approximately 3 cm/s to optimally activate C-tactile nerve fibres, provides effective pain relief.

METHODS

Petal is a multicentre, randomised, parallel-group interventional superiority trial conducted in the John Radcliffe Hospital (Oxford University Hospitals NHS Foundation Trust, Oxford, UK) and the Royal Devon and Exeter Hospital (Royal Devon University Healthcare NHS Foundation Trust, Exeter, UK). Neonates without neurological abnormalities who were born at 35 weeks gestational age or more and required a blood test via a heel lance in the first week of life were randomly assigned (1:1) to receive parental touch for 10 s either before (intervention group) or after (control group) the clinically required heel lance. Randomisation was managed at the Oxford site using a web-based minimisation algorithm with allocation concealment. The primary outcome measure was the magnitude of noxious-evoked brain activity in response to the heel lance measured with electroencephalography (EEG). Secondary outcome measures were Premature Infant Pain Profile-Revised (PIPP-R) score, development of tachycardia, and parental anxiety score. For all outcomes, the per-protocol effect was estimated via complier average causal effect analysis on the full analysis set. The trial is registered on ISRCTN (ISRCTN14135962) and ClinicalTrials.gov (NCT04901611).

FINDINGS

Between Sept 1, 2021, and Feb 7, 2023, 159 parents were approached to participate in the study, and 112 neonates were included. 56 neonates were randomly assigned to the intervention group of parental stroking before the heel lance and 56 to the control group of parental stroking after the heel lance. The mean of the magnitude of the heel lance-evoked brain activity was 0·85 arbitrary units (a.u.; SD 0·70; n=39; a scaled magnitude of 1 a.u. represents the expected mean response to a heel lance in term-aged neonates) in the intervention group and 0·91 a.u. (SD 0·76; n=43) in the control group. Therefore, the primary outcome did not differ significantly between groups, with a mean difference of -0·11 a.u. (lower in intervention group; SD 0·77; 95% CI -0·42 to 0·20; p=0·38; n=82). No significant difference was observed across secondary outcomes. The PIPP-R difference in means was 1·10 (higher in intervention group, 95% CI -0·42 to 2·61; p=0·15; n=100); the odds ratio of becoming tachycardic was 2·08 (95% CI 0·46 to 9·46; p=0·34, n=105) in the intervention group with reference to the control group; and the difference in parental State-Trait Anxiety Inventory-State score was -0·44 (higher in control group; SD 6·85; 95% CI -2·91 to 2·02; p=0·72; n=106). One serious adverse event (desaturation) occurred in a neonate randomly assigned to the control group, which was not considered to be related to the study.

INTERPRETATION

Parental stroking delivered at an optimal speed to activate C-tactile fibres for a duration of 10 s before the painful procedure did not significantly change neonates' magnitude of pain-related brain activity, PIPP-R score, or development of tachycardia. The trial highlighted the challenge of translating an experimental researcher-led tactile intervention into a parent-led approach, and the value of involving parents in their baby's pain management.

FUNDING

Wellcome Trust and Bliss.

State of the Art in Pediatric Anesthesia: A Narrative Review about the Use of Preoperative Time

This review delves into the challenge of pediatric anesthesia, underscoring the necessity for tailored perioperative approaches due to children's distinctive anatomical and physiological characteristics. Because of the vulnerability of pediatric patients to critical incidents during anesthesia, provider skills are of primary importance. Yet, almost equal importance must be granted to the adoption of a careful preanesthetic mindset toward patients and their families that recognizes the interwoven relationship between children and parents. In this paper, the preoperative evaluation process is thoroughly examined, from the first interaction with the child to the operating day. This evaluation process includes a detailed exploration of the medical history of the patient, physical examination, optimization of preoperative therapy, and adherence to updated fasting management guidelines. This process extends to considering pharmacological or drug-free premedication, focusing on the importance of preanesthesia re-evaluation. Structural resources play a critical role in pediatric anesthesia; components of this role include emphasizing the creation of child-friendly environments and ensuring appropriate support facilities. The results of this paper support the need for standardized protocols and guidelines and encourage the centralization of practices to enhance clinical efficacy.

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.

Electroanatomical Adaptations in the Guinea Pig Heart from Neonatal to Adulthood

Background

Electroanatomical adaptations during the neonatal to adult phase have not been comprehensively studied in preclinical animal models. To explore the impact of age as a biological variable on cardiac electrophysiology, we employed neonatal and adult guinea pigs, which are a recognized animal model for developmental research.

Methods

Healthy guinea pigs were categorized into three age groups (neonates, n=10; younger adults, n=13; and older adults, n=26). Electrocardiogram (ECG) recordings were collected in vivo from anesthetized animals (2-3% isoflurane). A Langendorff-perfusion system was employed for optical assessment of epicardial action potentials and calcium transients, using intact excised heart preparations. Optical data sets were analyzed and metric maps were constructed using Kairosight 3.0.

Results

The allometric relationship between heart weight and body weight diminishes with age, as it is strongest at the neonatal stage (R 2 = 0.84) and completely abolished in older adults (R 2 = 1E-06). Neonatal hearts exhibit circular activation waveforms, while adults show prototypical elliptical shapes. Neonatal conduction velocity (40.6±4.0 cm/s) is slower than adults (younger adults: 61.6±9.3 cm/s; older adults: 53.6±9.2 cm/s). Neonatal hearts have a longer action potential duration (APD) and exhibit regional heterogeneity (left apex; APD30: 68.6±5.6 ms, left basal; APD30: 62.8±3.6), which was absent in adult epicardium. With dynamic pacing, neonatal hearts exhibit a flatter APD restitution slope (APD70: 0.29±0.04) compared to older adults (0.49±0.04). Similar restitution characteristics are observed with extrasystolic pacing, with a flatter slope in neonatal hearts (APD70: 0.54±0.1) compared to adults (Younger adults: 0.85±0.4; Older adults: 0.95±0.7). Finally, neonatal hearts display unidirectional excitation-contraction coupling, while adults exhibit bidirectionality.

Conclusion

The transition from neonatal to adulthood in guinea pig hearts is characterized by transient changes in electroanatomic properties. Age-specific patterns can influence cardiac physiology, pathology, and therapies for cardiovascular diseases. Understanding postnatal heart development is crucial to evaluating therapeutic eligibility, safety, and efficacy.

What is Known

Age-specific cardiac electroanatomical characteristics have been documented in humans and some preclinical animal models. These age-specific patterns can influence cardiac physiology, pathology, and therapies for cardiovascular diseases.

What the Study Adds

Cardiac electroanatomical characteristics are age-specific in guinea pigs, a well-known preclinical model for developmental studies. Age-dependent adaptations in cardiac electrophysiology are readily observed in the electrocardiogram recordings and via optical mapping of epicardial action potentials and calcium transients. Our findings reveal unique activation and repolarization characteristics between neonatal and adult animals.

Right and left ventricular mass development in early infancy: Correlation of electrocardiographic changes with echocardiographic measurements

BACKGROUND

Right ventricular mass indexed to body surface area (RVMI) decreases and left ventricular mass index (LVMI) increases rapidly and substantially during early infancy. The relationship between these sizeable mass transformations and simultaneous electrocardiographic changes have not been previously delineated.

METHODS

Normal term infants (#45 initially enrolled) were prospectively evaluated at 2 days and at 2-week, 2-month, and 4-month clinic visits. Ventricular masses were estimated with 2D echocardiographic methods. QRS voltages were measured in leads V1, V6, I and aVF.

RESULTS

Mean QRS axis shifted from 135 (95%CI 124, 146) to 65 degrees (95%CI 49, 81) and correlated with both RVMI decrease and LVMI increase (R = 0.46⁎ vs. 0.25†, respectively. *p < 0.01, †p < 0.05). As RVMI decreased from mean 28.1 (95%CI 27.1, 29.1) to 23.3 g/m2 (95%CI 21.4, 25.2) so did V1R and V6S voltages. RVMI changes correlated with V1R, V6S, and V1R + V6S voltages (R = 0.29*, 0.23† and 0.35*, respectively. *p < 0.01, †p < 0.05) but not with V1R/S ratio. As LVMI increased from 44.6 (95%CI 42.9, 46.3) to 55.4 g/m2 (95%CI 52.3, 58.5) V6R and V6Q increased but V1S voltage did not. LVMI changes correlated with V6R, V6R-S, and V6(Q + R)-S voltages (R = 0.31*, 0.34*, and 0.38* respectively. *p < 0.01) but not with V1S or V6R/S (R = 0.01 and 0.18 respectively, p = NS).

CONCLUSIONS

During early infancy the RVMI decrease correlates best with the QRS axis shift and V1R + V6S voltage, and the LVMI increase correlates best with V6R-S and V6(Q + R)-S voltages.

Effect of QT interval-prolonging drugs taken in pregnancy on the neonatal QT interval

Introduction: Acquired QT interval prolongations due to drug side effects can result in detrimental arrhythmia. Maternal use of placenta-permeable drugs may lead to fetal exposure, thus leading to an increased risk of neonatal QT prolongation and arrhythmia. Objectives: This study aimed to evaluate the influence of maternal QT-prolonging medication on the neonatal QT interval. Methods: In the prospective KUNO-Kids health study, an ongoing population-based birth cohort, we classified maternal medications according to the known risk of QT interval prolongation. Effects on the neonatal QT interval were tested by linear regression analyses, correcting for perinatal confounders (birth weight, gestational age, birth mode, and age at ECG recording). Subgroup analyses were performed for selective serotonin reuptake inhibitors, proton pump inhibitors, and antihistamine dimenhydrinate. Logistic regression analysis was performed using a QTc of 450 ms as the cut-off value. Results: A total of 2,550 pregnant women received a total of 3,990 medications, of which 315 were known to increase the risk of QT prolongation, resulting in 105 (4.1%) neonates exposed in the last month of pregnancy. Overall, the mean age of the neonates at ECG was 1.9 days and the mean QTc (Bazett) was 414 ms. Univariate (regression coefficient -2.62, p = 0.288) and multivariate (regression coefficient -3.55, p = 0.146) regression analyses showed no significant effect of fetal medication exposure on the neonatal QT interval, neither in the overall nor in the subgroup analysis. Logistic regression analysis showed no association of exposure to maternal medication with an increased risk of neonatal QT interval prolongation (OR (odds ratio) 0.34, p = 0.14). Conclusion: The currently used maternal medication results in a relevant number of fetuses exposed to QT interval-prolonging drugs. In our cohort, exposure was found to have no effect on the neonatal QT interval.

Adapting to a new environment: postnatal maturation of the human cardiomyocyte

The postnatal mammalian heart undergoes remarkable developmental changes, which are stimulated by the transition from the intrauterine to extrauterine environment. With birth, increased oxygen levels promote metabolic, structural and biophysical maturation of cardiomyocytes, resulting in mature muscle with increased efficiency, contractility and electrical conduction. In this Topical Review article, we highlight key studies that inform our current understanding of human cardiomyocyte maturation. Collectively, these studies suggest that human atrial and ventricular myocytes evolve quickly within the first year but might not reach a fully mature adult phenotype until nearly the first decade of life. However, it is important to note that fetal, neonatal and paediatric cardiac physiology studies are hindered by a number of limitations, including the scarcity of human tissue, small sample size and a heavy reliance on diseased tissue samples, often without age-matched healthy controls. Future developmental studies are warranted to expand our understanding of normal cardiac physiology/pathophysiology and inform age-appropriate treatment strategies for cardiac disease.

Cardiac Arrhythmias Requiring Electric Countershock during the Neonatal Period-A Systematic Review

BACKGROUND

In neonates, cardiac arrhythmias are rare. Electric countershock therapy is an effective alternative to drug therapy for neonatal arrhythmias. There are no randomized controlled studies investigating electric countershock therapy in neonates.

OBJECTIVE

To identify all studies and publications describing electric countershock therapy (including defibrillation, cardioversion, and pacing) in newborn infants within 28 days after birth, and to provide a comprehensive review of this treatment modality and associated outcomes.

METHODS

For this systematic review we searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Cumulative Index to Nursing and Allied Health Literature (CINAHL). All articles reporting electric countershock therapy in newborn infants within 28 days after birth were included.

RESULTS

In terms of figures, 113 neonates who received electric countershock due to arrhythmias were reported. Atrial flutter (76.1%) was the most common arrhythmia, followed by supraventricular tachycardia (13.3%). Others were ventricular tachycardia (9.7%) and torsade de pointes (0.9%). The main type of electric countershock therapy was synchronized cardioversion (79.6%). Transesophageal pacing was used in twenty neonates (17.7%), and defibrillation was used in five neonates (4.4%).

CONCLUSION

Electric countershock therapy is an effective treatment option in the neonatal period. In atrial flutter especially, excellent outcomes are reported with direct synchronized electric cardioversion.

The scale of scientific evidence behind the current ESC clinical guidelines

Background

European Society of Cardiology (ESC) clinical practice guidelines are currently considered as an essential tool supporting many cardiologists in clinical decision-making not only in Europe but all-over the world. In this study we analyzed these recommendations regarding their class of recommendations (COR) and level of evidence (LOE) to detect how solid is the scientific background behind these recommendations.

Methods

We have abstracted all the current guidelines defined as "the guidelines available on the ESC website by 01 October 2022". All recommendations were classified according to their COR (Class I, IIa, IIb, or III) and LOE (A, B, or C). As every topic has different number of recommendations, we have used the median values in comparisons between different topics to give all the topics the same weight.

Results

Current ESC guidelines consist of 37 clinical topics including a total of 4289 recommendations. Their distribution was 2140 with a median of 49.9% in Class I, Class II and Class III were 1825 with a median of 42.6% and 324 with a median of 7.5% respectively. LOE A was only present in 667(15.5%) recommendations, 1285(30%) in LOE B, while LOE C was behind the majority of the recommendations, 2337 with a median of 54.5%.

Conclusion

Although ESC guidelines are considered a gold standard for management of cardiovascular diseases, but surprisingly more than half of its recommendations are based on such scientific evidence. Deficiency in clinical trials is not the same across all guideline's topics, some are needier for clinical research.

Tolerability and Safety of Lacosamide in Neonatal Population

Lacosamide is a newer antiepileptic medication used in refractory neonatal seizures with limited safety and efficacy data. This case series spans 4 years and includes 38 neonates cared for in the neonatal, pediatric, and cardiovascular intensive care units, who received lacosamide for refractory seizures. Because lacosamide affects atrioventricular node function in adults, among other metrics, electrocardiogram (ECG) changes were monitored closely in these neonates. Within this cohort, 2 neonates were found to have atrial bigeminy on ECG and telemetry. Otherwise, lacosamide was generally well tolerated with sleepiness being the most common symptom noted. This case series reports data on the tolerability of lacosamide and emphasizes the importance of monitoring key cardiac intervals with ECG before and after the use of lacosamide in this population.

Correlation between the level of evidence and the class of recommendations concerning the pharmacological aspects of the Guidelines of the European Society of Cardiology

Background The reliability of the recommendations affecting the clinical decisions is being continuously weighed in everyday practice (Gershlick, 2018). The objective of our study was to assess the consistency of the evidence behind the recommendations. Methods We narrowed our focus on the pharmacotherapeutic aspects of the most recent 38 European Society of Cardiology guidelines and analyzed the correlation between the level of evidence (LoE) classified as A, B and C and the class of recommendations (CoR) subdivided into I, IIa, IIb and III. Results Contrary to the majority of recommendations based on a LoE C (43,0%), fewer recommendations were proposed on heavily evidence-supported LoE A (23.8%), which percentage increased with subsequent updates of the guidelines. The most common recommendation was CoR I (44,9%), while the least common recommendation was CoR III (9,2%). While a similar share of A (39,1%) and C (30,1%) LoE shaped the CoR I nearly half (48,8%) of the CoR III were based on LoE C. Conversely, the overwhelming majority of the recommendations within the scope of LoE A were indisputably strong and classified as CoR I (73,7%). Conclusion The pharmacological aspects of the ESC guidelines are predominantly based on LoE C. A greater number of pharmacological recommendations are based on LoE A in comparison to the general ones. Various constraints significantly skew the credibility due to paucity of scientific data. A more nuanced approach is needed, as the guidelines cannot completely substitute the clinical experience and the patient-centered approach in shaping the optimal therapeutic outcome.

QTc Interval Reference Values and Their (Non)-Maturational Factors in Neonates and Infants: A Systematic Review

QTc interval measurement is a widely used screening tool to assess the risk of cardiac diseases, arrhythmias, and is a useful biomarker for pharmacovigilance. However, the interpretation of QTc is difficult in neonates due to hemodynamic maturational changes and uncertainties on reference values. To describe trends in QTc values throughout infancy (1 year of life), and to explore the impact of (non)-maturational changes and medicines exposure, a structured systematic review (PROSPERO CRD42022302296) was performed. In term neonates, a decrease was observed over the first week of life, whereafter values increased until two months of age, followed by a progressive decrease until six months. A similar pattern with longer QTc values was observed in preterms. QTc is influenced by cord clamping, hemodynamic changes, therapeutic hypothermia, illnesses and sleep, not by sex. Cisapride, domperidone and doxapram result in QTc prolongation in neonates. Further research in this age category is needed to improve primary screening practices and QTcthresholds, earlier detection of risk factors and precision pharmacovigilance.

Normal ECG standards and percentile charts for infants, children and adolescents

BACKGROUND

Normal ECG standards in newborns, infants, children and adolescents have been collected and published by many authors. Only those by Davignon et al., Rijinbeek et al. and our two studies covered all ages from birth to adolescence. The standards reflecting the growth and development of the heart in infants, children and adolescents remained to be studied and explored.

METHODS

We selected from our ECG database, after discussions and consultation, 15 key ECG parameters and analyzed for their age- and sex-specific mean, standard deviation and 2nd to 98th percentiles and their percentile charts were constructed.

RESULTS

The ranges and distributions of the normal ECG standards, means and 2nd to 98th percentiles of 15 key parameters were established.

CONCLUSION

A complete set of normal ECG standards of 15 key parameters from birth to adolescents is available for clinicians and researchers.

Generationenübergreifende Betreuung von Patienten mit tachykarden Rhythmusstörungen

Die Versorgung von Patienten mit Rhythmusstörungen hat sich in den letzten Jahrzehnten von einer rein konservativ medikamentösen Therapie zu einer echten kurativen Therapie mit Beseitigung des arryhthmogenen Substrats durch technisch immer ausgereiftere Möglichkeiten im Sinn der elektrophysiologische Untersuchung (EPU) und Ablation entwickelt. Parallel dazu haben sich in pädiatrisch-kardiologischen Zentren rhythmologische Spezialambulanzen zur Betreuung von Patienten mit Ionenkanalerkrankungen etabliert. Deren Aufgabe besteht in der generationenübergreifenden Betreuung von ganzen Familien, mit dem Ziel, präventiv, durch entsprechende Beratung und Führung, maligne Rhythmusstörungen primär zu verhindern.

Cerebral Seizures in an Adolescent with Jervell and Lange-Nielsen Syndrome: It May Not Be Epilepsy

A 13-year-old girl with Jervell and Lange-Nielsen syndrome associated congenital long QT syndrome (LQTS) and central deafness was admitted for generalized seizures. LQTS had been diagnosed after birth and confirmed at genetic testing. β-blocker treatment was immediately started. Despite this, since the age of 12 months, recurrent cerebral seizures occurred leading to the diagnosis of epilepsy. Anti-convulsive therapy was initiated but without success. At the last admission, nadolol dosage seemed infratherapeutic. Considering malignant ventricular arrhythmias as the cause of seizures, the β-blocker dosage was adjusted to weight and levels of magnesium and potassium optimized. Furthermore, the patient received an implantable Medtronic Reveal LINQ Recorder^®. Since then, the adolescent has been asymptomatic with no arrhythmia documented. LQTS is due to one or more mutations of genes coding for ion channels. It may induce malignant ventricular arrhythmias and is a major cause of sudden cardiac death in children. Generalized cerebral seizures are extra-cardiac manifestations caused by decreased cerebral perfusion during ventricular arrhythmia. They are commonly misinterpreted as manifestations of epilepsy. For any patient with known or unknown LQTS who presents seizures with resistance to anti-convulsive therapy, a cardiac electrophysiological investigation should be performed promptly to ensure etiological diagnosis and optimize treatment.

Right Ventricular Function in Neonates During Early Postnatal Period: A Prospective Observational Study

Previous echocardiographic studies were mainly focused on preterm infants and early fetal-to-neonatal transition period, whereas little is known about changes in the parameters of the right ventricular (RV) function after 72 h of life. Our aim was to quantitatively characterize potential changes in RV function by echocardiography in healthy term newborns between the third and the seventh day of life. We conducted a prospective observational study in 35 full-term newborns, in whom we performed echocardiographic examinations on the third and the seventh day of life. We assessed RV function, output and afterload and found a significant increase in all tissue Doppler velocities as well as in RV longitudinal strain, a higher mean RV outflow tract velocity time integral and lower myocardial performance index (MPI'), whereas the tricuspid annular plane systolic excursion, RV filling pattern, and RV outflow tract acceleration time were not significantly different between the third and the seventh day of life. Conclusions: Increased RV systolic and diastolic myocardial velocities, cardiac output and longitudinal deformation and decreased RV MPI' between the third and the seventh day of life point to a reduction of RV afterload and adaptive myocardial maturation in term newborns during this period. Moreover, PW-TDI and 2D speckle-tracking echocardiography seem to be more sensitive for evaluating RV function in comparison with M-mode echocardiography and pulsed-wave Doppler analysis of RV filling.

Multicentre, randomised controlled trial to investigate the effects of parental touch on relieving acute procedural pain in neonates (Petal)

INTRODUCTION

Newborn infants routinely undergo minor painful procedures as part of postnatal care, with infants born sick or premature requiring a greater number of procedures. As pain in early life can have long-term neurodevelopmental consequences and lead to parental anxiety and future avoidance of interventions, effective pain management is essential. Non-pharmacological comfort measures such as breastfeeding, swaddling and sweet solutions are inconsistently implemented and are not always practical or effective in reducing the transmission of noxious input to the brain. Stroking of the skin can activate C-tactile fibres and reduce pain, and therefore could provide a simple and safe parent-led intervention for the management of pain. The trial aim is to determine whether parental touch prior to a painful clinical procedure provides effective pain relief in neonates.

METHODS AND ANALYSIS

This is a multicentre randomised controlled trial. A total of 112 neonates born at 35 weeks' gestation or more requiring a blood test in the first week of life will be recruited and randomised to receive parental stroking either preprocedure or postprocedure. We will record brain activity (EEG), cardiac and respiratory dynamics, oxygen saturation and facial expression to provide proxy pain outcome measures. The primary outcome will be the reduction of noxious-evoked brain activity in response to a heel lance. Secondary outcomes will be a reduction in clinical pain scores (Premature Infant Pain Profile-Revised), postprocedural tachycardia and parental anxiety.

ETHICS AND DISSEMINATION

The study has been approved by the London-South East Research Ethics Committee (ref: 21/LO/0523). The results will be widely disseminated through peer-reviewed publications, international conferences and via our partner neonatal charities Bliss and Supporting the Sick Newborn And their Parents (SSNAP). If the parental tactile intervention is effective, recommendations will be submitted via the National Health Service clinical guideline adoption process.

STUDY STATUS

Commenced September 2021.

TRIAL REGISTRATION NUMBER

NCT04901611; 14 135 962.

Accelerated idioventricular rhythm in a healthy newborn: frightening but non-threatening

Accelerated idioventricular rhythm is a rare but benign form of ventricular tachycardia which might be challenging to differentiate from other more worrisome forms. We present the case of a healthy newborn diagnosed with an accelerated idioventricular rhythm which is spontaneously terminated without the need for medical therapy.

Diagnostic Accuracy of the 12-Lead Electrocardiogram in the First 48 Hours of Life for Newborns of a Parent with Congenital Long QT Syndrome

BACKGROUND

Long QT syndrome (LQTS) is an autosomal dominant disorder characterized by a prolonged QT interval. ECG screening in the first 48 hours of life may be misleading, even in newborns with a genotype-positive LQTS parent.

OBJECTIVE

To determine the ECG's diagnostic accuracy in the first 48 hours of life for neonates born to a parent with LQTS.

METHODS

Retrospective review of all neonates born at Mayo Clinic to a parent with ≥1 pathogenic variant in a LQTS-causative gene who had least 1 ECG in the first 48 hours and genetic test results were available. Sensitivity and specificity of the diagnostic ECG were calculated using QTc thresholds of 440, 450, 460, and 470 ms.

RESULTS

Overall, 74 infants (36 [49%] females) were included (mean QTc on first ECG 489 ± 54 ms; 68% LQTS genotype-positive). Mean QTc in the first 48 hours for neonates that ultimately were genotype-positive was greater (506 ± 52 ms) compared to genotype-negative neonates (455 ± 41 ms; p=0.0004). When using a recommended threshold QTc of ≥ 440 ms, 6/50 (12%) genotype-positive neonates were missed (underdiagnosed) and 17/24 (71%) genotype-negative neonates were overdiagnosed (sensitivity: 88%, specificity: 29%).

CONCLUSIONS

The newborn ECG should not be used in isolation to make the diagnosis of LQTS since it will result in many misclassifications. Genetic testing must be initiated prior to discharge, and proper anticipatory guidance is vital while awaiting test results.

Characterisation of neonatal cardiac dynamics using ordinal partition network

The maturation of the autonomic nervous system (ANS) starts in the gestation period and it is completed after birth in a variable time, reaching its peak in adulthood. However, the development of ANS maturation is not entirely understood in newborns. Clinically, the ANS condition is evaluated with monitoring of gestational age, Apgar score, heart rate, and by quantification of heart rate variability using linear methods. Few researchers have addressed this problem from the perspective nonlinear data analysis. This paper proposes a new data-driven methodology using nonlinear time series analysis, based on complex networks, to classify ANS conditions in newborns. We map 74 time series given by RR intervals from premature and full-term newborns to ordinal partition networks and use complexity quantifiers to discriminate the dynamical process present in both conditions. We obtain three complexity quantifiers (permutation, conditional, and global node entropies) using network mappings from forward and reverse directions, and considering different time lags and embedding dimensions. The results indicate that time asymmetry is present in the data of both groups and the complexity quantifiers can differentiate the groups analysed. We show that the conditional and global node entropies are sensitive for detecting subtle differences between the neonates, particularly for small embedding dimensions (m < 7). This study reinforces the assessment of nonlinear techniques for RR interval time series analysis. Graphical Abstract.

Mexiletine Treatment for Neonatal LQT3 Syndrome: Case Report and Literature Review

Background: Early diagnosis of long QT type 3 (LQT3) syndrome during the neonatal period is of paramount clinical importance. LQT3 syndrome results in increased mortality and a mutation-specific response to treatment compared to other more common types of LQT syndrome. Mexiletine, a sodium channel blocker, demonstrates a mutation-specific QTc shortening effect in LQT3 syndrome patients. Case Presentation: A neonate manifested marked QTc prolongation after birth. An electrocardiogram (ECG) recording was performed due to positive family history of genetically confirmed LQT3 syndrome (SCN5A gene missense mutation Tyr1795Cys), and an association with sudden cardiac death was found in family members. The mexiletine QTc normalizing effect (QTc shortening from 537 to 443 ms), practical issues related to oral mexiletine treatment of our young patient, along with a literature review regarding identification and mexiletine treatment in infants with LQT3 syndrome are presented. Conclusions: Mexiletine could be considered in the treatment of high-risk LQT3 patients already in the neonatal period in addition to b-blocker therapy. Availability of standardized commercial mexiletine pediatric formulas, serum mexiletine level analyses, and future prospective studies are needed to evaluate the potential beneficial effect of early mexiletine treatment on the incidence of future acute cardiac events in these high-risk LQT syndrome patients.

Recording an ECG With a Smartwatch in Newborns and Young Children: Feasibility and Perspectives

Correlating symptoms with arrhythmia in neonates and young children is often difficult because of their sporadic and unpredictable nature. We show that it is possible to register an ECG with a smartwatch in neonates and young children and provide illustrative cases of supraventricular tachycardia and complete atrioventricular block identified with this technology.

Defining the normal QT interval in newborns: the natural history and reference values for the first 4 weeks of life

AIMS

Evaluation of the neonatal QT interval is important to diagnose arrhythmia syndromes and evaluate side effects of drugs. We aimed at describing the natural history of the QT interval duration during the first 4 weeks of life and to provide reference values from a large general population sample.

METHODS AND RESULTS

The Copenhagen Baby Heart Study is a prospective general population study that offered cardiac evaluation of newborns. Eight-lead electrocardiograms were obtained and analysed with a computerized algorithm with manual validation. We included 14 164 newborns (52% boys), aged 0-28 days, with normal echocardiograms. The median values (ms, 2-98%ile) for the corrected intervals QTc (Bazett), QTc (Hodges), QTc (Fridericia), and QTc (Framingham) were 419 (373-474), 419 (373-472), 364 (320-414), and 363 (327-405). During the 4 weeks, we observed a small decrease of QTcFramingham, and an increase of QTcHodges (both P < 0.01), while QTcBazett and QTcFridericia did not change (P > 0.05). Applying published QT interval cut-off values resulted in 5-25% of the newborns having QT prolongation. Uncorrected QT intervals decreased linearly with increasing heart rate (HR). Sex and infant size did not affect the QT interval and the gestational age (GA) only showed an effect when comparing the extreme low- vs. high GA groups (≤34 vs. ≥42 weeks, P = 0.021).

CONCLUSION

During the 4 weeks QTcFramingham and QTcHodges showed minor changes, whereas QTcBazett and QTcFridericia were stable. The QT interval was unaffected by sex and infant size and GA only showed an effect in very premature newborns. Reference values for HR-specific uncorrected QT intervals may facilitate a more accurate diagnosis of newborns with abnormal QT intervals.

Early Identification of Prolonged QT Interval for Prevention of Sudden Infant Death

Introduction: Long QT syndrome is the main arrhythmogenic disease responsible for sudden death in infants, especially in the first days of life. Performing an electrocardiogram in newborns could enable early diagnosis and adoption of therapeutic measures focused on preventing lethal arrhythmogenic events. However, the inclusion of an electrocardiogram in neonatal screening protocols still remains a matter of discussion. To comprehensively analyse the potential clinical value of performing an electrocardiogram and subsequent follow-up in a cohort of newborns. Methods: Electrocardiograms were performed in 685 neonates within the first week of life. One year follow-up was performed if QTc > 450 ms identified. Comprehensive genetic analysis using massive sequencing was performed in all cases with QTc > 470 ms. Results: We identified 54 neonates with QTc > 450 ms/ <470 ms; all normalized QTc values within 6 months. Eight cases had QTc > 480 ms at birth and, if persistent, pharmacological treatment was administrated during follow-up. A rare variant was identified as the potential cause of long QT syndrome in five cases. Three cases showed a family history of sudden arrhythmogenic death. Conclusions: Our prospective study identifies 0.14% of cases with a definite long QT, supporting implementation of electrocardiograms in routine pediatric protocols. It is an effective, simple and non-invasive approach that can help prevent sudden death in neonates and their relatives. Genetic analyses help to unravel the cause of arrhythmogenic disease in diagnosing neonates. Further, clinical assessment and genetic analysis of relatives allowed early identification of family members at risk of arrhythmias helping to adopt preventive personalized measures.

Single-centre retrospective analysis of the best timing for the QTc interval length assessment in neonates

Objective

To evaluate the best timing for ECG screening in order to diagnose long QT syndrome and lower, at the same time, the false positives.

Design

We retrospectively evaluated the corrected QT (QTc) interval in the clinical reports of the ECG screening performed, as per internal protocol.

Setting

An outpatient setting in our Unit of Neonatology and Pediatrics, Santa Maria Goretti Hospital in Latina, Italy.

Patients

We enrolled 3467 healthy neonates between 14 and 30 days of life.

Interventions

The newborns with abnormal QTc interval were invited to subsequent revaluation every 21 days, until normalisation or necessity to refer to a tertiary paediatric cardiology centre.

Main outcome measures

Difference in QTc according to patients' characteristics and number of false positives at second ECG evaluation.

Results

At first evaluation, 249 (7.2%) newborns had prolonged QTc. We did not find any significant difference in the QTc length according to gestational age (p=0.40) and birth weight (p=0.81). As expected, girls had longer QTc than boys (p=0.01). Only 11 out of 240 (4.6%) and 1 out of 238 infants (0.4%) had persistently prolonged QTc at second and third ECG evaluation, respectively. The QTc decreased significantly at second (p<0.0001) and third evaluation (p=0.0035).

Conclusions

In our study, we showed that a single screening performed in healthy infants after 60 days of life could reduce the risk of false positives, with a beneficial impact on public national health system and the chance to start early therapy in case of long QT syndrome.

Precordial ECG Amplitudes in the Days After Birth: Electrocardiographic Changes During Transition from Fetal to Neonatal Circulation

During the first month of life, the relation between right and left ventricular function is markedly altered. We aimed at describing the electrocardiographic transition from fetal to neonatal circulation by investigating changes in R- and S-wave amplitudes in V1 and V6 during the first 4 weeks of life. This study is part of the prospective, population-based Copenhagen Baby Heart Study offering cardiac evaluation to newborns within 28 days from birth. ECGs were obtained and analyzed using a computerized algorithm. A total of 14,577 newborns (52% boys), median age of 11.0 days, were included. All had normal echocardiograms. Within 28 days from birth, the amplitudes in V1 decreased: R-V1 (1262 µV day0; 947 µV day28, p < 0.001) and S-V1 (1240 µV day0; 473 µV day28, p < 0.001). An increase was observed for R-V6 (825 µV day0; 1196 µV day28, p = 0.002), while S-V6 decreased (830 µV day0; 634 µV day28, p = 0.003). For all amplitudes, interindividual variation was large (up to 20 times). The amplitudes were not affected by sex (p > 0.05), but R-V1, R-V6, and S-V6 positively correlated with newborn weight (p < 0.01). R-V1 and S-V6 showed positive correlation with gestational age (p < 0.05). In conclusion, systematic analyses of ECGs from healthy newborns showed significant decreases in R-V1, S-V1, and S-V6 amplitudes, while R-V6 increased. Interindividual variation was large, making ECGs unlikely as a sensitive tool for diagnosing congenital heart diseases. Our data may serve as updated, digitalized reference values in newborns.

Supraventricular tachycardias in the first year of life: what is the best pharmacological treatment? 24 years of experience in a single centre

Background

Supraventricular tachycardias (SVTs) are common in the first year of life and may be life-threatening. Acute cardioversion is usually effective, with both pharmacological and non-pharmacological procedures. However, as yet no international consensus exists concerning the best drug required for a stable conversion to sinus rhythm (maintenance treatment). Our study intends to describe the experience of a single centre with maintenance drug treatment of both re-entry and automatic SVTs in the first year of life.

Methods

From March 1995 to April 2019, 55 patients under one year of age with SVT were observed in our Centre. The SVTs were divided into two groups: 45 re-entry and 10 automatic tachycardias. As regards maintenance therapy, in re-entry tachycardias, we chose to start with oral flecainide and in case of relapses switched to combined treatment with beta-blockers or digoxin. In automatic tachycardias we first administered a beta-blocker, later combined with flecainide or amiodarone when ineffective.

Results

The patients’ median follow-up time was 35 months. In re-entry tachycardias, flecainide was effective as monotherapy in 23/45 patients (51.1%) and in 20/45 patients (44.4%) in combination with nadolol, sotalol or digoxin (overall 95.5%). In automatic tachycardias, a beta-blocker alone was effective in 3/10 patients (30.0%), however, the best results were obtained when combined with flecainide: overall 9/10 (90%).

Conclusions

In this retrospective study on pharmacological treatment of SVTs under 1 year of age the combination of flecainide and beta-blockers was highly effective in long-term maintenance of sinus rhythm in both re-entry and automatic tachycardias.

Validation of Normal P-Wave Parameters in a Large Unselected Pediatric Population of North-Western Romania: Results of the CARDIOPED Project

AIMS

Reference values of the P-wave on 12 lead electrocardiograms are lacking for children and adolescents in Eastern Europe. Hence, the present study is aimed at determining the standard values of the P-wave in children and adolescents based on ECG data from the CARDIOPED project, a large-scale general population of children who participated in a screening program in Transylvania, Romania.

METHODS AND RESULTS

A total of 22,411 ECGs of participants aged 6 to 18 years old from a school-based ECG screening were obtained between February 2015 and December 2015 in Transylvania, Romania. Three pediatric cardiologists manually reviewed each ECG. P-wave duration, voltage, axis, and correlation with gender and age were analyzed. The mean P-wave duration was 88 ± 10.7 ms, with a maximum duration of 128 ms. P-wave showed a positive correlation with age but did not differ between sexes. There was a positive correlation between the P-wave duration and the heart rate, but not with the body max index. The mean P-wave axis was 40.4 ± 31.1, and the mean P-wave amplitude was 0.12 ± 0.03 mV.

CONCLUSION

In this study on many pediatric subjects, we have provided normal limits for the P-wave in Romanian children aged 6-18 years. Our findings are useful for creating interpretation guidelines for pediatric ECG.

Exercise Training-Induced Repolarization Abnormalities Masquerading as Congenital Long QT Syndrome

BACKGROUND

The diagnosis of long QT syndrome (LQTS) is rather straightforward. We were surprised by realizing that, despite long-standing experience, we were making occasional diagnostic errors by considering as affected subjects who, over time, resulted as not affected. These individuals were all actively practicing sports-an observation that helped in the design of our study.

METHODS

We focused on subjects referred to our center by sports medicine doctors on suspicion of LQTS because of marked repolarization abnormalities on the ECG performed during the mandatory medical visit necessary in Italy to obtain the certificate of eligibility to practice sports. They all underwent our standard procedures involving both a resting and 12-lead ambulatory ECG, an exercise stress test, and genetic screening.

RESULTS

There were 310 such consecutive subjects, all actively practicing sports with many hours of intensive weekly training. Of them, 111 had a normal ECG, different cardiac diseases, or were lost to follow-up and exited the study. Of the remaining 199, all with either clear QTc prolongation and/or typical repolarization abnormalities, 121 were diagnosed as affected based on combination of ECG abnormalities with positive genotyping (QTc, 482±35 ms). Genetic testing was negative in 78 subjects, but 45 were nonetheless diagnosed as affected by LQTS based on unequivocal ECG abnormalities (QTc, 472±33 ms). The remaining 33, entirely asymptomatic and with a negative family history, showed an unexpected and practically complete normalization of the ECG abnormalities (their QTc shortened from 492±37 to 423±25 ms [P<0.001]; their Schwartz score went from 3.0 to 0.06) after detraining. They were considered not affected by congenital LQTS and are henceforth referred to as "cases." Furthermore, among them, those who resumed similarly heavy physical training showed reappearance of the repolarization abnormalities.

CONCLUSION

It is not uncommon to suspect LQTS among individuals actively practicing sports based on marked repolarization abnormalities. Among those who are genotype-negative, >40% normalize their ECG after detraining, but the abnormalities tend to recur with resumption of training. These individuals are not affected by congenital LQTS but could have a form of acquired LQTS. Care should be exercised to avoid diagnostic errors.

Clinical characterization and outcome of prolonged heart rate-corrected QT interval among children with syndactyly

Prolonged heart rate-corrected QT (QTc) interval is an independent risk factor for sudden cardiac death, which is the hallmark of Timothy syndrome (TS). There are little data on children with syndactyly and QTc prolongation.To evaluate the characteristics and long-term outcomes in children with syndactyly, and to attempt to identify TS in patients with syndactyly and QTc prolongation.This is a retrospective case-control study of children with syndactyly who visited Beijing Jishuitan Hospital between July 2003 and February 2013. The patients with prolonged QTc intervals are matched 1:4 with patients without prolongation. Genetic testing of the CACNA1C gene is routinely performed in patients with QTc prolongation.The mean age at admission is 3.4 ± 2.3 years. Compared with the normal QTc group, those with QTc prolongation showed higher frequencies of congenital heart disease (11.8% vs 1.5%, P = .042), mental retardation and facial dysmorphia (11.8% vs 0, P = .004), and T wave alternans (23.5% vs 4.4%, P = .01). In the multivariable analysis, only T wave alternans (OR = 10.61, 95%CI: 1.39-81.16, P = .023) is independently associated with QTc prolongation in patients with syndactyly. One child with QTc prolongation had a mutation in the CACNA1C gene. No patients with prolonged QTs interval met the threshold for TS.Children with syndactyly and prolonged QTc interval had more multisystem diseases and electrocardiography abnormalities. T wave alternans is independently associated with QTc prolongation in patients with syndactyly.

Inherited cardiac arrhythmias

The main inherited cardiac arrhythmias are long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. These rare diseases are often the underlying cause of sudden cardiac death in young individuals and result from mutations in several genes encoding ion channels or proteins involved in their regulation. The genetic defects lead to alterations in the ionic currents that determine the morphology and duration of the cardiac action potential, and individuals with these disorders often present with syncope or a life-threatening arrhythmic episode. The diagnosis is based on clinical presentation and history, the characteristics of the electrocardiographic recording at rest and during exercise and genetic analyses. Management relies on pharmacological therapy, mostly β-adrenergic receptor blockers (specifically, propranolol and nadolol) and sodium and transient outward current blockers (such as quinidine), or surgical interventions, including left cardiac sympathetic denervation and implantation of a cardioverter-defibrillator. All these arrhythmias are potentially life-threatening and have substantial negative effects on the quality of life of patients. Future research should focus on the identification of genes associated with the diseases and other risk factors, improved risk stratification and, in particular for Brugada syndrome, effective therapies.

Complex and Novel Arrhythmias Precede Stillbirth in Fetuses With De Novo Long QT Syndrome

BACKGROUND

Long QT syndrome (LQTS) is a leading cause of sudden cardiac death in early life and has been implicated in ≈10% of sudden infant deaths and unexplained stillbirths. The purpose of our study was to use fetal magnetocardiography to characterize the electrophysiology and rhythm phenotypes of fetuses with de novo and inherited LQTS variants and identify risk factors for sudden death before birth.

METHODS

We reviewed the fetal magnetocardiography database from the University of Wisconsin Biomagnetism Laboratory for fetuses with confirmed LQTS. We assessed waveform intervals, heart rate, and rhythm, including the signature LQTS rhythms: functional 2° atrioventricular block, T-wave alternans, and torsade de pointes (TdP).

RESULTS

Thirty-nine fetuses had pathogenic variants in LQTS genes: 27 carried the family variant, 11 had de novo variants, and 1 was indeterminate. De novo variants, especially de novo SCN5A variants, were strongly associated with a severe rhythm phenotype and perinatal death: 9 (82%) showed signature LQTS rhythms, 6 (55%) showed TdP, 5 (45%) were stillborn, and 1 (9%) died in infancy. Those that died exhibited novel fetal rhythms, including atrioventricular block with 3:1 conduction ratio, QRS alternans in 2:1 atrioventricular block, long-cycle length TdP, and slow monomorphic ventricular tachycardia. Premature ventricular contractions were also strongly associated with TdP and perinatal death. Fetuses with familial variants showed a lower incidence of signature LQTS rhythm (6/27=22%), including TdP (3/27=11%). All were live born.

CONCLUSIONS

The malignancy of de novo LQTS variants was remarkably high and demonstrate that these mutations are a significant cause of stillbirth. Their ability to manifest rhythms not known to be associated with LQTS increases the difficulty of echocardiographic diagnosis and decreases the likelihood that a resultant fetal loss is attributed to LQTS. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03047161.

Ventricular repolarization abnormalities: the electrocardiographic track of cardiac tumoural involvement in an infant with tuberous sclerosis complex. A case report

BACKGROUND

Primary cardiac tumours are rare in children. Against this backdrop, Doppler echocardiogram is the main diagnostic procedure, while electrocardiogram (ECG) usually plays a secondary role, by detecting tumoural consequences as cardiac arrhythmias and chambers overload. We describe a case where an electrocardiographic sign was the cornerstone to diagnosis and surveillance of an infant with a cardiac rhabdomyoma.

CASE SUMMARY

A female infant was referred for cardiac evaluation to elucidate an electrocardiographic abnormality, detected during investigation of seizures. She had recently been diagnosed with epilepsy and was under three different anticonvulsants for appropriate control. Cardiovascular symptoms were absent. Skin inspection revealed hypochromic macules. Respiratory and cardiovascular examinations were normal, as well as laboratorial tests and chest radiography. Electrocardiogram (ECG) showed dome-shaped ST-segment elevation in V2 and V3. Transthoracic echocardiogram unveiled a single hyper-echogenic node (0.4 cm²) in the interventricular septum. Cardiac chambers had normal size and function and Doppler analysis was also normal. No specific medication was used to treat the tumour. During follow-up, she remained free of cardiac symptoms. Eighteen months after her first visit to the cardiologist, routine clinical assessment, ECG, and transthoracic Doppler echocardiogram normal results stated the spontaneous and complete involution of the tumoural lesion.

DISCUSSION

Convex ST-segment elevation, generally related to myocardial injury, is unusual in paediatric patients. Once it occurs in asymptomatic individuals within this age bracket, exclusion of cardiac tumours is mandatory. However, data regarding the accuracy of such electrocardiographic marker in this clinical setting are still to be defined.

Electrocardiographic Screening in the First Days of Life for Diagnosing Long QT Syndrome: Findings from a Birth Cohort Study in Germany

INTRODUCTION

Newborn sudden infant death syndrome (SIDS) has failed to decrease in the last decades, and a third of the neonatal cases occurred within the first 6 days of life. The long QT syndrome (LQTS) is a genetic disease with a prevalence of 1 in 2,000 live births and contributes to almost 10% of SIDS cases. Early identification of LQTS through electrocardiogram (ECG) screening is likely to reduce mortality.

METHODS AND RESULTS

In this ongoing prospective study we evaluated 2,251 ECGs from newborns participating in the KUNO Kids birth cohort study between July 2015 and July 2018. ECGs were recorded at a mean age of 2.0 days (IQR 0 days). The QT interval was corrected for heart rate using Bazett's formula (QTc). A QTc between 451 and 460, 461-470, and >470 ms was measured in 23 (1.0), 14 (0.6), and 62 (2.8%) participants, respectively. Fourteen neonates (0.62%) were admitted and monitored because their initial QTc was ≥500 ms. In 2 genetically analyzed participants, a mutation was found. One disease-causing for LQTS type 1 and the other of unclear significance. Cascade screening revealed affected members in both families.

CONCLUSION

A standardized neonatal ECG screening in the first days of life is able to identify neonates with a relevant transient form of prolonged QT intervals and to aid diagnosing congenital LQTS.

Non-contact physiological monitoring of preterm infants in the Neonatal Intensive Care Unit

The implementation of video-based non-contact technologies to monitor the vital signs of preterm infants in the hospital presents several challenges, such as the detection of the presence or the absence of a patient in the video frame, robustness to changes in lighting conditions, automated identification of suitable time periods and regions of interest from which vital signs can be estimated. We carried out a clinical study to evaluate the accuracy and the proportion of time that heart rate and respiratory rate can be estimated from preterm infants using only a video camera in a clinical environment, without interfering with regular patient care. A total of 426.6 h of video and reference vital signs were recorded for 90 sessions from 30 preterm infants in the Neonatal Intensive Care Unit (NICU) of the John Radcliffe Hospital in Oxford. Each preterm infant was recorded under regular ambient light during daytime for up to four consecutive days. We developed multi-task deep learning algorithms to automatically segment skin areas and to estimate vital signs only when the infant was present in the field of view of the video camera and no clinical interventions were undertaken. We propose signal quality assessment algorithms for both heart rate and respiratory rate to discriminate between clinically acceptable and noisy signals. The mean absolute error between the reference and camera-derived heart rates was 2.3 beats/min for over 76% of the time for which the reference and camera data were valid. The mean absolute error between the reference and camera-derived respiratory rate was 3.5 breaths/min for over 82% of the time. Accurate estimates of heart rate and respiratory rate could be derived for at least 90% of the time, if gaps of up to 30 seconds with no estimates were allowed.

Early Postnatal Heart Rate Variability in Healthy Newborn Infants

Background

Despite the increasing interest in fetal and neonatal heart rate variability (HRV) analysis and its potential use as a tool for early disease stratification, no studies have previously described the normal trends of HRV in healthy babies during the first hours of postnatal life.

Methods

We prospectively recruited 150 healthy babies from the postnatal ward and continuously recorded their electrocardiogram during the first 24 h after birth. Babies were included if born in good condition and stayed with their mother. Babies requiring any medication or treatment were excluded. Five-minute segments of the electrocardiogram (non-overlapping time-windows) with more than 90% consecutive good quality beats were included in the calculation of hourly medians and interquartile ranges to describe HRV trends over the first 24 h. We used multilevel mixed effects regression with auto-regressive covariance structure for all repeated measures analysis and t-tests to compare group differences. Non-normally distributed variables were log-transformed.

Results

Nine out of 16 HRV metrics (including heart rate) changed significantly over the 24 h [Heart rate p < 0.01; Standard deviation of the NN intervals p = 0.01; Standard deviation of the Poincaré plot lengthwise p < 0.01; Cardiac sympathetic index (CSI) p < 0.01; Normalized high frequency power p = 0.03; Normalized low frequency power p < 0.01; Total power p < 0.01; HRV index p = 0.01; Parseval index p = 0.03], adjusted for relevant clinical variables. We observed an increase in several HRV metrics during the first 6 h followed by a gradual normalization by approximately 12 h of age. Between 6 and 12 h of age, only heart rate and the normalized low frequency power changed significantly, while between 12 and 18 h no metric, other than heart rate, changed significantly. Analysis with multilevel mixed effects regression analysis (multivariable) revealed that gestational age, reduced fetal movements, cardiotocography and maternal chronic or pregnancy induced illness were significant predictors of several HRV metrics.

Conclusion

Heart rate variability changes significantly during the first day of life, particularly during the first 6 h. The significant correlations between HRV and clinical risk variables support the hypothesis that HRV is a good indicator of overall wellbeing of a baby and is sensitive to detect birth-related stress and monitor its resolution over time.