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Background: The AliveCor KardiaMobile (ACKM) is a remote electrocardiogram (ECG) monitoring device. Little research has been conducted on its accuracy with pediatric patients. This prospective study aims to compare the ACKM six-lead device with a standard fifteen-lead ECG in measuring the QTc, QRS, and axis in pediatric patients.Methods: Pediatric patients ages 5 to 21 years were enrolled prospectively to have their ECG recorded using an ACKM six-lead device following a recording with the standard fifteen-lead ECG. A pediatric electrophysiologist measured the QTc, QRS interval, and QRS axis for both ECGs. Bland-Altman analysis was performed to assess agreement among measurements.Results: The study included 141 patients. The mean age was 12.3 ± 4.4 years. Average heart rate was 79 ± 16 bpm. The mean difference in the QTc measurements for a paired standard ECG and ACKM was -0.6 ms [95% confidence interval -48 to 47 ms]. Of the ACKM QTc measurements, 117 (83%) were within 30 ms of the standard ECG. The mean difference in paired QRS measurements was -1.3 ms [95% confidence interval -23 to 21 ms]. Of the ACKM QRS measurements, 134 (95%) were within 20 ms of the standard ECG. The measured axis was the same for 84% of ACKM and standard ECGs. Conclusions: Over 80% of the ACKM six-lead ECGs produced QTc, QRS, and axis deviation measurements within a clinically useful range of the standard ECG. However, it is not accurate enough to be used consistently in place of a standard ECG for QTc and QRS measurement for pediatric patients.

Sudden cardiac arrest in pediatric patients is a rare occurrence. Supraventricular tachycardia without the presence of ventricular preexcitation in pediatric patients with a structurally normal heart is generally considered benign. Previous literature in adults reported a subset of patients in whom SVT was suspected to be the primary trigger of sudden cardiac arrest. We performed a single-center, retrospective cohort study of pediatric patients without known heart disease, 1-21 years of age, presenting with aborted SCA between 2009 and 2019. We collected diagnostic studies in all patients to identify the etiology of the aborted SCA. Thirty patients met the inclusion criteria. The median age at the time of SCA was 15.2 years. The etiology of SCA was identified in 23 (77%) patients. Of the seven patients with unknown diagnosis after initial diagnostic studies, three patients subsequently developed fast SVT that was presumed to be the etiology of the initial SCA. These three patients had varying diagnoses of atrioventricular nodal reentry tachycardia, ectopic atrial tachycardia, and a concealed accessory pathway with atrioventricular reentrant tachycardia. After ablation or medical treatment of the SVT substrate, no further tachyarrhythmias were observed. Pediatric patients presenting with an aborted SCA of unknown etiology ought to be considered for electrophysiology testing to elicit occult SVT substrates that may lead to a malignant ventricular tachyarrhythmia.

TANGO2 deficiency disorder (TDD), an autosomal recessive disease first reported in 2016, is characterized by neurodevelopmental delays, seizures, intermittent ataxia, hypothyroidism and life-threatening metabolic and cardiac crises. The purpose of this study was to define the natural history of TDD.Data were collected from an ongoing natural history study of TDD patients enrolled between February 2019 - May 2022. Data were obtained through phone-based parent interviews and medical record review.Data were collected from 73 patients (56% male) from 57 unrelated families in 17 different countries. The median age of participants at time of data collection was 9.0 years (IQR 5.3-15.9 years, range fetal - 31 years). A total of 24 different TANGO2 alleles were observed. Patients demonstrated normal development in early infancy with progressive delays in developmental milestones thereafter. Symptoms including ataxia, dystonia and speech difficulties typically starting between the ages of 1-3 years. A total of 48 (66%) patients suffered metabolic crises and, of these, 29/48 (73%) developed cardiac crises. Metabolic crises were significantly decreased after initiation of B-complex or multivitamins.We provide the most comprehensive review of natural history of TDD and provide important observational data suggesting B-complex or multivitamins may prevent metabolic crises.

Block in accessory pathway (AP) conduction with adenosine has been previously described. However, conduction characteristics of these APs has not been well defined to date. All patients with APs

Background: Congenitally corrected transposition of the great arteries (ccTGA) is a rare disease of unknown cause. We aimed to better understand familial recurrence patterns. Methods: An international, multicentre, retrospective cohort study was conducted in 29 tertiary hospitals in 6 countries between 1990 and 2018, entailing investigation of 1043 unrelated ccTGA probands. Results: Laterality defects and atrioventricular block at diagnosis were observed in 29.9% and 9.3%, respectively. ccTGA was associated with primary ciliary dyskinesia in 11 patients. Parental consanguinity was noted in 3.4% cases. A congenital heart defect was diagnosed in 81 relatives from 69 families, 58% of them being first-degree relatives, including 28 siblings. The most prevalent defects in relatives were dextro-transposition of the great arteries (28.4%), laterality defects (13.6%), and ccTGA (11.1%); 36 new familial clusters were described, including 8 pedigrees with concordant familial aggregation of ccTGA, 19 pedigrees with familial co-segregation of ccTGA and dextro-transposition of the great arteries, and 9 familial co-segregation of ccTGA and laterality defects. In one family co-segregation of ccTGA, dextro-transposition of the great arteries and heterotaxy syndrome in 3 distinct relatives was found. In another family, twins both displayed ccTGA and primary ciliary dyskinesia. Conclusions: ccTGA is not always a sporadic congenital heart defect. Familial clusters as well as evidence of an association between ccTGA, dextro-transposition of the great arteries, laterality defects and in some cases primary ciliary dyskinesia, strongly suggest a common pathogenetic pathway involving laterality genes in the pathophysiology of ccTGA.

Definitive treatment of supraventricular tachycardia (SVT) substrate involves catheter ablation. While objective success rates have been well established, long-term subjective patient experiences have not been well described. We quantify a subjective cure rate and characterize long-term patient experience after acutely successful ablation. A cross-sectional survey of pediatric patients with accessory pathways or atrioventricular nodal reentrant tachycardia who underwent acutely successful ablation from 2008 to 2012 was performed. Data were obtained from medical records and patient surveys. Patients with congenital heart disease other than patent ductus arteriosus, patent foramen ovale, or coronary artery abnormalities were excluded. Statistical analyses included Student’s t-test and χ2 analysis for continuous and categorical variables, respectively. Surveys were sent to 153 patients of which 147 responded with median follow-up of 7.2 (IQR 6.1–8.5) years. Of the 147 responders, 124 (84%) patients reported cure with a male predominance. Symptoms were present in 130/147 (88%) patients pre-ablation and in 53/147 (36%) post-ablation. Among those with post-ablation symptoms, 50/53 (94%) reported symptomatic improvement. Recurrence occurred in 23/147 (16%) patients and was more prevalent following cryoablation. Ablation of SVT substrate can be curative with excellent long-term results and patient satisfaction. Long-term subjective cure rate is high and there is a substantial decrease in symptoms post-ablation. Many patients continue to have symptoms following ablation; however, the majority of these patients consider themselves cured and symptoms can be attributed to other etiologies. Recurrence is uncommon and occurs more frequently following cryoablation.

The standard for ambulatory arrhythmia detection in children is the Holter monitor. The Zio XT (Zio) patch has been FDA-approved for use in adults. However, its utility in children has not been directly compared with the Holter. We studied the ability to detect arrhythmias and patient comfort of the Zio versus the Holter in children. Patients22 years old were prospectively enrolled to wear the Holter and Zio simultaneously for 48 hours at our institution. Detection of clinically significant arrhythmias was compared using McNemar's test. Wear-time and artifact time was compared using Wilcoxon sign test. Patient satisfaction ratings were analyzed with paired t tests. Two hundred patients (57% male) were included for analysis. The median age was 13.5 years (range 23 days to 21.7 years), and 40% had heart disease. The Zio and Holter had comparable median wear-times, 48.2 hours (interquartile range [IQR] 45.8 to 50.2]) versus 48.0 (48.0 to 48.0), respectively, p = 0.14, but the Zio had less artifact than the Holter, 2.8% (IQR 1.1 to 8.6) versus 5.6% (2.4 to 15.7), respectively, p0.001. There was no difference in detection of clinically significant arrhythmias for the Zio versus the Holter (p = 0.23), however 75% of patients preferred the Zio over the Holter (p0.001) due to lack of wires and the ability to shower. In conclusion, the Zio patch is as good as the Holter monitor in detection of clinically significant arrhythmias in children with less artifact. Patients/parents more often preferred the Zio over the Holter.

TANGO2 deficiency disorder (TDD) is an autosomal recessive disease associated with metabolic crisis, lethal cardiac arrhythmias, and cardiomyopathy. Data regarding treatment, management, and outcomes of cardiac manifestations of TDD are lacking.The purpose of this study was to describe TDD-related cardiac crises.Retrospective multicenter chart review was made of TDD patients admitted with cardiac crises, defined as development of ventricular tachycardia (VT), cardiomyopathy, or cardiac arrest during metabolic crises.Twenty-seven children were admitted for 43 cardiac crises (median age 6.4 years; interquartile range [IQR] 2.4-9.8 years) at 14 centers. During crisis, QTc prolongation occurred in all (median 547 ms; IQR 504-600 ms) and a type I Brugada pattern in 8 (26%). Arrhythmias included VT in 21 (78%), supraventricular tachycardia in 3 (11%), and heart block in 1 (4%). Nineteen patients (70%) developed cardiomyopathy, and 20 (74%) experienced a cardiac arrest. There were 10 deaths (37%), 6 related to arrhythmias. In 5 patients, recalcitrant VT occurred despite use of antiarrhythmic drugs. In 6 patients, arrhythmias were controlled after extracorporeal membrane oxygenation (ECMO) support; 5 of these patients survived. Among 10 patients who survived VT without ECMO, successful treatment included intravenous magnesium, isoproterenol, and atrial pacing in multiple cases and verapamil in 1 patient. Initiation of feeds seemed to decrease VT events.TDD-related cardiac crises are associated with a high risk of arrhythmias, cardiomyopathy, cardiac arrest, and death. Although further studies are needed, early recognition and appropriate treatment are critical. Acutely, intravenous magnesium, isoproterenol, atrial pacing, and ECMO as a last resort seem to be the best current treatment options, and early initiation of feeds may prevent VT events.

Cardiac involvement associated with multi-system inflammatory syndrome in children has been extensively reported, but the prevalence of cardiac involvement in children with SARS-CoV-2 infection in the absence of inflammatory syndrome has not been well described. In this retrospective, single centre, cohort study, we describe the cardiac involvement found in this population and report on outcomes of patients with and without elevated cardiac biomarkers. Those with multi-system inflammatory syndrome in children, cardiomyopathy, or complex CHD were excluded. Inclusion criteriaz were met by 80 patients during the initial peak of the pandemic at our institution. High-sensitivity troponin T and/or N-terminal pro-brain type natriuretic peptide were measured in 27/80 (34%) patients and abnormalities were present in 5/27 (19%), all of whom had underlying comorbidities. Advanced respiratory support was required in all patients with elevated cardiac biomarkers. Electrocardiographic abnormalities were identified in 14/38 (37%) studies. Echocardiograms were performed on 7/80 patients, and none demonstrated left ventricular dysfunction. Larger studies to determine the true extent of cardiac involvement in children with COVID-19 would be useful to guide recommendations for standard workup and management.

Introduction: Cardiopulmonary exercise testing (CPET) is an important tool in assessing the functional status of patients with pulmonary hypertension (PH). During CPET, ECG is used as marker of exercise induced ischemia. We hypothesize that ECG changes with exercise may be an early indicator of clinical worsening in PH and could predict adverse outcomes. Methods: Clinical, hemodynamic, and CPET data of 101 PH patients who underwent CPET between 2013 and 2019 were included. ECGs were analyzed for ST depressions and T wave inversions during the earliest CPET in this time frame, along with coincident hemodynamic data. These data were correlated to adverse outcomes, including shunt creation (atrial septostomy or POTTs shunt), lung transplantation, and death. Results: Median age was 19 y (7-40 y, IQR 12-26), 68% were female, and median follow up time was 3 y (1-8 y, IQR 1-5). Sixteen patients had an adverse outcome (8 shunt creation, 4 lung transplant, 7 death). Twenty-two patients demonstrated significant ST/T wave changes with exercise, 18 ST depressions and 9 T wave inversions. Multivariate regression, including pulmonary arterial pressure, revealed exercise induced ST/T wave changes to be an independent predictor of procedure-free survival (without lung transplantation or shunt creation) (hazard ratio 11.10, p=.006). Only 21% with ST/T wave changes demonstrated procedure-free survival vs 85% without. Conclusions: ST/T wave changes on exercise ECG are significantly associated with adverse outcomes in PH on a medium term follow up study. These ECG changes with exercise can be used as early indicators of clinical worsening in PH and predictors of adverse outcomes.

A diagnosis of Brugada pattern in paediatric or adolescent patients is rare. COVID-19 is characterised by fevers and a pro-inflammatory state, which may serve as inciting factors for Brugada pattern. Recently described in two adult patients, we report the first case of Brugada pattern in an adolescent with COVID-19.

Objectives This study sought to demonstrate the feasibility of electromechanical wave imaging (EWI) for localization of accessory pathways (AP) prior to catheter ablation in a pediatric population. Background Prediction of AP locations in patients with Wolff-Parkinson-White syndrome is currently based on analysis of 12-lead electrocardiography (ECG). In the pediatric population, specific algorithms have been developed to aid in localization, but these can be unreliable. EWI is a noninvasive imaging modality relying on a high frame rate ultrasound sequence capable of visualizing cardiac electromechanical activation. Methods Pediatric patients with ventricular pre-excitation presenting for catheter ablation were imaged with EWI immediately prior to the start of the procedure. Two clinical pediatric electrophysiologists predicted the location of the AP based on ECG. Both EWI and ECG predictions were blinded to the results of catheter ablation. EWI and ECG localizations were subsequently compared with the site of successful ablation. Results Fifteen patients were imaged with EWI. One patient was excluded for poor echocardiographic windows and the inability to image the entire ventricular myocardium. EWI correctly predicted the location of the AP in all 14 patients. ECG analysis correctly predicted 11 of 14 (78.6%) of the AP locations. Conclusions EWI was shown to be capable of consistently localizing accessory pathways. EWI predicted the site of successful ablation more frequently than analysis of 12-lead ECG. EWI isochrones also provide anatomical visualization of ventricular pre-excitation. These findings suggest that EWI can predict AP locations, and EWI may have the potential to better inform clinical electrophysiologists prior to catheter ablation procedures.

OBJECTIVES We aimed to measure the frequency and factors associated with anodal stimulation in a pediatric population with epicardial pacing leads. BACKGROUND In bipolar pacemakers, capture of the myocardium typically occurs at the cathode. However, AS with capture at the anode has been described. This has not been described in epicardial pacemakers. METHODS Retrospective data were collected from patients ≤ 21 years of age with permanent bipolar epicardial ventricular pacemakers from 1/2017 to 1/2018. AS was defined as a clear change on surface ECG in at least one of the 12 leads assessed by two blinded pediatric electrophysiologists. RESULTS Twenty-four bipolar leads in 23 patients were included in the study. One patient had both biventricular leads tested. Median age was 7.1 years (IQR 5.0-10.9), weight was 20.9 kg (IQR 16.5-33.5), and 65% were male. Testing was performed at a median of 2.8 years (IQR 1.6-6.1) after implant. Congenital heart disease was present in 57%. Complete heart block was the pacemaker indication in 78%. AS was identified in 16/24 (67%) of leads tested. Identification of AS was associated with presence of congenital heart disease (p = 0.004) and 3DD between electrodes (p = 0.04). CONCLUSIONS AS is common in pediatric patients and was associated with a history of congenital heart disease and greater estimated 3DD between electrodes. The prevalent nature of AS may allow clinicians to utilize existing pacemakers as multisite pacing systems.

Background: Supraventricular tachycardia (SVT) without the presence of ventricular preexcitation in pediatric patients with a structurally normal heart is generally considered a benign condition. However, in children with fast atrioventricular nodal (AVN) conduction, SVT can be rapid and potentially life threatening. Objective: We report cases in which cardiac arrest was the first manifestation of SVT. Methods: This is a single center retrospective review. Patients less than 21 …

Introduction Congenitally corrected transposition of the great arteries (ccTGA) is a rare disease of unknown aetiology. We aimed to better understand familial recurrence pattern. Methods An international, multicentre, retrospective cohort study was conducted in 29 tertiary hospitals in 6 countries between 1990 and 2018, leading to investigate 1043 unrelated ccTGA probands. Results Atrioventricular block at diagnosis and laterality defects were observed in 35.4% and 29.9%, respectively. ccTGA associated with primary ciliary dyskinesia in 10 patients. Parental consanguinity was noted in 3.4% cases. A congenital heart defect was diagnosed in 81 relatives from 69 families, 58% of them being first-degree relatives, including 28 siblings. The most prevalent defects in relatives were dextro-transposition of the great arteries (d-TGA: 28.4%), laterality defects (13.6%) and ccTGA (11.1%); 36 new familial clusters were described, including 8 pedigrees with concordant familial aggregation of ccTGA, 19 pedigrees with familial co-segregation of ccTGA and d-TGA and 9 familial co-segregation of ccTGA and laterality defects. In one family there was co-segregation of ccTGA, d-TGA and heterotaxy syndrome in 3 distinct relatives. Conclusion ccTGA is not always a sporadic congenital heart defect. Familial clusters as well as evidence of an association between ccTGA, d-TGA, laterality defects and in some cases primary ciliary dyskinesia strongly suggest a common pathogenetic pathway involving laterality genes in the pathophysiology of ccTGA.

Intro: AVNRT is a common mechanism of SVT in pediatric patients. Catecholamines such as isoproterenol (ISO) are routinely given during post ablation (ABL) testing to confirm acute success. In light of its recent significant cost increase, the aim of our study was to determine if ISO is necessary in all pediatric patients after AVNRT ablation to ensure acute procedural success. Method: Retrospective study of patients Result: We identified 232 patients with AVNRT of whom 65 (28%) met the study criteria; 123 (53%) were excluded for requiring ISO to induce AVNRT prior to ABL, 23 (10%) for CHD, 12 (5%) with presumed AVNRT and 9 (4%) with an unsuccessful ABL. The average age was 14.4 yrs (±3.5) and 54% were female. All patients received anesthesia, 40/65 were intubated (62%). Evidence of slow pathway conduction (Spath) (AH jump with atrial extrastimulus testing, presence of AV nodal echo beats or PR>RR) was seen in 35/65 patients (54%). Patients were divided into 2 groups: group 1 (n= 57, 88%) consisted of patients without inducible TACHY post ABL while receiving ISO, group 2 (n = 8, 12%) of patients in whom TACHY was inducible with ISO thus required further ABL. There was no difference between the groups with regards to sex, age, intubation status, prior use of antiarrhythmic meds, or in the incidence of Spath (31/57, 54% vs. 4/8, 50%, p=1). Four of the 8 patients in group 2 with no evidence of Spath had inducible TACHY with ISO. Conclusion: We found that 12% of pediatric patients who did not require ISO to induce AVNRT prior to ABL had inducible TACHY only with ISO after AVNRT ABL. Presence of dual AV nodal physiology after ABL lesions did not predict inducibility of AVNRT on ISO, and 50% of the patients with no evidence of slow pathway conduction by conventional testing had inducible AVNRT with ISO. ISO testing is useful in all pediatric patients to test for inducibility following catheter ablation of AVNRT.

OBJECTIVES: Multisystem inflammatory syndrome in children (MIS-C) has spread through the pediatric population during the coronavirus disease 2019 pandemic. Our objective for the study was to report the prevalence of conduction anomalies in MIS-C and identify predictive factors for the conduction abnormalities. METHODS: We performed a single-center retrospective cohort study of pediatric patients RESULTS: Thirty-two patients met inclusion criteria. Median age at admission was 9 years. Six of 32 patients (19%) were found to have first-degree AVB, with a median longest PR interval of 225 milliseconds (interquartile range 200–302), compared with 140 milliseconds (interquartile range 80–178) in patients without first-degree AVB. The onset of AVB occurred at a median of 8 days after the initial symptoms and returned to normal 3 days thereafter. No patients developed advanced AVB, although 1 patient developed a PR interval >300 milliseconds. Another patient developed new-onset right bundle branch block, which resolved during hospitalization. Cardiac enzymes, inflammatory markers, and cardiac function were not associated with AVB development. CONCLUSIONS: In our population, there is a 19% prevalence of first-degree AVB in patients with MIS-C. All patients with a prolonged PR interval recovered without progression to high-degree AVB. Patients admitted with MIS-C require close electrocardiogram monitoring during the acute phase.

Approximately, 1.7 million individuals in the United States have been infected with SARS-CoV-2, the virus responsible for the novel coronavirus disease-2019 (COVID-19). This has disproportionately impacted adults, but many children have been infected and hospitalised as well. To date, there is not much information published addressing the cardiac workup and monitoring of children with COVID-19. Here, we share the approach to the cardiac workup and monitoring utilised at a large congenital heart centre in New York City, the epicentre of the COVID-19 pandemic in the United States.

INTRODUCTION: Relative contraindications for adenosine use include heart transplant history and the anti-platelet agent dipyridamole. In an initial prospective study, the safety and efficacy of adenosine to induce atrioventricular (AV) block was demonstrated in pediatric and young adult heart transplant recipients. Over half of this cohort was on dipyridamole, which was suspended before testing. This prospective follow-up study evaluates the safety and efficacy of an adenosine dosing protocol in healthy young patients maintained on dipyridamole after heart transplant. METHODS: After routine cardiac biopsy (4/2016 – 6/2017), a temporary ventricular pacing catheter was placed and adenosine was dosed in stepwise increments until AV block occurred (maximum dose 200mcg/kg up to 12mg). The primary outcome was clinically significant asystole (≥ 12 seconds). Secondary outcomes included dose of adenosine eliciting AV block, AV block duration, dysrhythmias and patient reported symptoms. Incidence and 95% confidence intervals for categorical outcomes were calculated. Paired outcomes were compared to the parent study. RESULTS: Thirty of 39 eligible patients (5 – 24 years) were tested. No patient (0%, CI 0 – 8%) experienced clinically significant asystole. AV block occurred in 29/30 patients (97%, CI 86 – 100%). The median dose causing AV block was 50mcg/kg (vs. 100mcg/kg off dipyridamole; P=0.011). Seventeen patients (57%, CI 39 – 72%) required less adenosine to achieve AV block on dipyridamole; six (20%) required more. AV block occurred only at doses ≥25mcg/kg. Length of block, frequency of atrial/ventricular ectopy and incidence of subjective symptoms after adenosine were not different on dipyridamole. No atrial fibrillation/flutter occurred. CONCLUSION: AV block occurs often at twofold lower adenosine doses in healthy pediatric and young adult heart transplant recipients taking oral dipyridamole, as compared to previous testing of the same cohort off dipyridamole. Results still suggest that initial dosing of 25mcg/kg (max 0.8mg) with stepwise escalation poses low risk of prolonged asystole.

The current understanding of the genotype-phenotype relationship in arrhythmogenic cardiomyopathy continues to evolve. Initial studies described arrhythmogenic right ventricular cardiomyopathy as a fibrofatty replacement of cardiac myocytes in the right ventricle associated with a high incidence of ventricular arrhythmias. Newer studies suggest a broader phenotypic array of disease driven by distinct genetic mutations. This includes arrhythmogenic left ventricular cardiomyopathy associated with DSP mutations. Herein, we describe an unusual case of an adolescent male with syncope and findings of ALVC secondary to DSP mutation.

Background Initial propranolol recommendations for infantile hemangioma published in 2013 were intended as provisional best practices to be updated as evidence-based data emerged. Methods A retrospective multicenter study was performed to evaluate utility of prolonged monitoring after first propranolol dose and escalation(s). Inclusion criteria included diagnosis of hemangioma requiring propranolol of greater than or equal to 0.3 mg/kg per dose, younger than 2 years, and heart rate monitoring for greater than or equal to 1 hour. Data collected included demographics, dose, vital signs, and adverse events. Results A total of 783 subjects met inclusion criteria; median age at initiation was 112 days. None of the 1148 episodes of prolonged monitoring warranted immediate intervention or drug discontinuation. No symptomatic bradycardia or hypotension occurred during monitoring. Mean heart rate change from baseline to 1 hour was –8.19/min (±15.54/min) and baseline to 2 hours was –9.24/min (±15.84/min). Three preterm subjects had dose adjustments because of prescriber concerns about asymptomatic vital sign changes. No significant difference existed in pretreatment heart rate or in heart rate change between individuals with later adverse events during treatment and those without. Conclusion Prolonged monitoring for initiation and escalation of oral propranolol rarely changed management and did not predict future adverse events. Few serious adverse events occurred during therapy; none were cardiovascular.

Arrhythmia localization prior to catheter ablation is critical for clinical decision making and treatment planning. The current standard lies in 12-lead electrocardiogram (ECG) interpretation, but this method is non-specific and anatomically limited. Accurate localization requires intracardiac catheter mapping prior to ablation. Electromechanical Wave Imaging (EWI) is a high frame-rate ultrasound modality capable of non-invasively mapping the electromechanical activation in all cardiac chambers in vivo. In this study, we evaluate 3D-rendered EWI as a technique for consistently localizing the accessory pathway (AP) in Wolff-Parkinson-White (WPW) pediatric patients. A 2000 Hz EWI diverging sequence was used to transthoracically image 13 patients with evidence of ECG pre-excitation, immediately prior to catheter ablation and after successful ablation whenever possible. 3D-rendered activation maps were generated by co-registering and interpolating the 4 resulting multi-2D isochrones. A blinded electrophysiologist predicted the AP location on 12-lead ECG prior to ablation. Double-blinded EWI isochrones and clinician assessments were compared to the successful ablation site as confirmed by intracardiac mapping using a segmented template of the heart with 19 ventricular regions. 3D-rendered EWI was shown capable of consistently localizing AP in all the WPW cases. Clinical ECG interpretation correctly predicted the origin with an accuracy of 53.8%, respectively 84.6% when considering predictions in immediately adjacent segments correct. Our method was also capable of assessing the difference in activation pattern from before to after successful ablation on the same patient. These findings indicate that EWI could inform current diagnosis and expedite treatment planning of WPW ablation procedures.

Obesity is associated with additional left ventricular hypertrophy (LVH) in adults with hypertrophic cardiomyopathy (HCM). It is not known whether obesity can lead to further LVH in children with HCM. Echocardiographic LV dimensions were determined in 504 children with HCM. Measurements of interventricular septal thickness (IVST) and posterior wall thickness (PWT), and patients' weight and height were recorded. Obesity was defined as a body mass index (BMI) ≥ 99th percentile for age and sex. IVST data was available for 498 and PWT data for 484 patients. Patient age ranged from 2 to 20 years (mean ± SD, 12.5 ± 3.9) and 340 (68%) were males. Overall, patient BMI ranged from 7 to 50 (22.7 ± 6.1). Obesity (BMI 18-50, mean 29.1) was present in 140 children aged 2-19.6 (11.3 ± 4.1). The overall mean IVST was 20.5 ± 9.6 mm and the overall mean PWT was 11.0 ± 8.4 mm. The mean IVST in the obese patients was 21.6 ± 10.0 mm and mean PWT was 13.3 ± 14.7 mm. The mean IVST in the non-obese patients was 20.1 ± 9.5 mm and mean PWT was 10.4 ± 4.3 mm. Obesity was not significantly associated with IVST (p = 0.12), but was associated with increased PWT (0.0011). Obesity is associated with increased PWT but not IVST in children with HCM. Whether obesity and its impact on LVH influences clinical outcomes in children with HCM needs to be studied.

Predictors of risk of lethal arrhythmic events (LAE) is poorly understood and may differ from adults in children with hypertrophic cardiomyopathy (HCM).The purpose of this study was to determine predictors of LAE in children with HCM.A retrospective data collection was performed on 446 children and teenagers 20 years and younger (290 [65%] male; mean age 10.1 ± 5.7 years) with idiopathic HCM from 35 centers. Patients were classified as group 1 (HCM with LAE) if having a secondary prevention implantable cardioverter-defibrillator (ICD) or primary prevention ICD with appropriate interventions or group 2 (HCM without LAE) if having a primary prevention ICD without appropriate interventions.There were 152 children (34%) in group 1 and 294 (66%) in group 2. Risk factors for group 1 by univariate analysis were septal thickness, posterior left ventricular (LV) wall thickness, lower LV outflow gradient, and Q wave3 mm in inferior electrocardiographic leads. Factors not associated with LAE were family history of SCD, abnormal blood pressure response to exercise, and ventricular tachycardia on ambulatory electrocardiographic monitoring. Risk factors for SCD by multivariate analysis were age at ICD placement (hazard ratio [HR] 0.9; P = .0025), LV posterior wall thickness z score (HR 1.02; P.005), and LV outflow gradient30 mm Hg (HR 2.0; P.006). LV posterior wall thickness z score ≥ 5 was associated with LAE.Risk factors for LAE appear different in children compared to adults. Conventional adult risk factors were not significant in children. Further prospective studies are needed to improve risk stratification for LAE in children with HCM.

Under environmental, firm and individual perspectives, this chapter examines the development and contributions of AIB-LAT over time and reviews the varied contributions in this volume, part of the AIB-LAT book series.

The purpose of the present study was to assess the effect that three positive attributes have on work performance among a sample of international locals. We measured the influence of self-efficacy, optimism and curiosity on performance in intercultural interactions. We argue that these traits contribute to performance when having intercultural interactions. Significant bivariate correlations were found between work performance and these traits separately. Moreover, the regression model that we proposed—including self-efficacy, optimism and curiosity—predicted work performance and that the individual attributes with higher significant contributions were self-efficacy and curiosity. We discuss the practical and theoretical importance of these preliminary finding and suggest future lines of research.

Background Advanced second- or third-degree heart block has been reported with variable incidence after surgery for congenital heart disease in children. We report the incidence of heart block requiring a pacemaker and describe the risk factors for this complication in a large multicenter study. Methods We performed a retrospective cohort study, using the Pediatric Health Information System database from 45 hospitals in the United States, for all children aged 18 years, discharged between January 1, 2004, and December 31, 2013, who underwent open surgery for congenital heart disease. Patients who had heart block and placement of a pacemaker during the same hospitalization were identified. Demographic characteristics, procedure and diagnostic codes, length of stay, and mortality were analyzed. Univariable and multivariable analyses were performed. Results There were 101,006 surgeries performed. The median age of patients was 0.5 years (interquartile range, 26 days to 3.2 years), and 1% of patients (n = 990) had heart block and placement of a pacemaker. Surgeries associated with the highest incidences of heart block and placement of a pacemaker included the double switch operation (15.6%), tricuspid valve (7.8%) and mitral valve (7.4%) replacement, atrial switch with ventricular septal defect repair (6.4%), and Rastelli operation (4.8%). On multivariable analysis, after controlling for surgical complexity, other comorbidities, age at surgery, admission year, and clustering by institution, patients with heart block and placement of a pacemaker had higher odds of mortality (odds ratio, 1.67; 95% confidence interval, 1.24-2.26; P Conclusions The incidence of postoperative heart block requiring permanent pacemaker placement immediately after congenital heart surgery is low (1%). However, these patients have higher mortality even after adjusting for heart surgery complexity.

Wolff–Parkinson–White (WPW) describes an accessory pathway (AP) that connects the atria and ventricles and allows preexcitation of the ventricle, manifested on the electrocardiogram (ECG) as a short PR interval and a delta wave. WPW syndrome describes the abnormal ECG pattern in patients with associated clinical cardiovascular symptoms, whereas “isolated ventricular preexcitation,” “asymptomatic WPW,” or “asymptomatic WPW syndrome” all refer to the abnormal ECG pattern without associated clinical cardiovascular symptoms. The clinical presentation of symptomatic WPW in young patients with structurally normal hearts can vary based on age and accessory pathway properties. Unfortunately, sudden cardiac death (SCD) can be the first manifestation in patients with WPW. Non-invasive modalities (ECG, ambulatory monitoring, and exercise testing) are used to risk stratify patients. A more invasive test (electrophysiology study) can then be used to identify high-risk pathways. Finally, radiofrequency and/or cryoablation are used to eliminate the accessory pathway and eliminate the risk of arrhythmia and SCD.

The clinical course of children with advanced heart block secondary to Lyme disease has not been well characterized. To review the presentation, management, and time to resolution of heart block due to Lyme disease in previously healthy children. An IRB approved single-center retrospective study was conducted of all patients

Smartphone applications that record a single-lead ECG are increasingly available. We sought to determine the utility of a smartphone application (AliveCor) to record supraventricular tachycardia (SVT) and to distinguish atrioventricular reentrant tachycardia (AVRT) from atrioventricular nodal reentrant tachycardia (AVNRT) in pediatric patients. A prior study demonstrated that interpretation of standard event and Holter monitors accurately identifies the tachycardia mechanism in only 45 % of recordings. We performed an IRB-approved prospective study in pediatric patients undergoing an ablation for SVT. Tracings were obtained by placing the smartphone in three different positions on the chest (PI-horizontal, PII-rotated 60° clockwise, and PIII-rotated 120° clockwise). Two blinded pediatric electrophysiologists jointly analyzed a pair of sinus and tachycardia tracings in each position. Tracings with visible retrograde P waves were classified as AVRT. The three positions were compared by Chi-square test. Thirty-seven patients (age 13.7 ± 2.8 years) were enrolled in the study. Twenty-four had AVRT, and 13 had AVNRT. One hundred and eight pairs of tracings were obtained. The correct diagnosis was made in 27/37 (73 %) with position PI, 28/37 (76 %) with PII, and 20/34 (59 %) with PIII (p = 0.04 for PII vs. PIII and p = NS for other comparisons). A single-lead ECG obtained with a smartphone monitor can successfully record SVT in pediatric patients and can predict the SVT mechanism at least as well as previously published reports of Holter monitors, along with the added convenience of not requiring patients to carry a dedicated monitor.

Background Three-dimensional electroanatomic mapping systems (3D mapping) allow the creation of an anatomic representation of the cardiac anatomy and real-time monitoring of transvenous pacing catheters. Their use to facilitate pacemaker (PM) and implantable cardioverter defibrillator (ICD) lead placement in the pediatric population has not been well defined. We sought to review our experience using 3D mapping as an adjunct to fluoroscopy for positioning of permanent PM and ICD leads in pediatric patients. Methods We performed a retrospective review of all patients ≤21 years of age who underwent PM or ICD implantation with the aid of the Ensite Velocity system (Ensite) from May 2012 to September 2014. Fluoroscopy was utilized in addition to 3D mapping to aid obtaining vascular access, to visualize fixation of the lead to the myocardium, and to evaluate lead length within the vasculature. Results Nineteen patients (mean age 14.6 ± 4.4 years) underwent placement of active fixation PM leads (N = 17) and/or ICD leads (N = 10) with the aid of Ensite. All leads were successfully placed (eight atrial, 19 ventricular). Fluoroscopic exposure was a mean of 3.2 minutes (± 2.8, 0.1–10.5). There was one lead dislodgement. Conclusions Ensite was used successfully as an adjunct to fluoroscopy in all patients in whom it was attempted to aid the placement of permanent transvenous PM and ICD leads. Future evaluation could focus on the use of 3D mapping systems to further minimize or eliminate fluoroscopy from PM and ICD implantations.

A high dose of oral flecainide has been used for acute termination of atrial fibrillation (AF) and atrial flutter or intra-atrial re-entry tachycardia (AFL-IART) in adults. The use of flecainide for these conditions in children has not been well described. We describe our institutional experience on acute termination of AF or AFL-IART in children with a single high dose of oral flecainide in a hospital setting. All patients who received a single high dose of oral flecainide from 2009 to 2016 who were21 years of age were included. Patients were treated only if AF or AFL-IART was less than 24 hours of duration. The dose was 300 mg for patients70 kg, 200 mg for patients 40 to 70 kg, and 5 mg/kg for patients40 kg. Charts were reviewed to determine demographic information, flecainide dose, termination of arrhythmia, and time to termination. There were 22 patients identified. The median age was 16 years (range 4.6 to 20.3) with a median weight of 75 kg (range 19 to 112). There were 13 patients with AF (11 with a normal heart, 85%) and 9 patients with AFL-IART (1 with a normal heart, 11%) (p 0.05). The median dose of flecainide given was 3.6 mg/kg (range 2.7 to 6.1) or 136 mg/m

Aims To clarify the clinical characteristics and outcomes of children with SCN5A-mediated disease and to improve their risk stratification. Methods and results A multicentre, international, retrospective cohort study was conducted in 25 tertiary hospitals in 13 countries between 1990 and 2015. All patients ≤ 16 years of age diagnosed with a genetically confirmed SCN5A mutation were included in the analysis. There was no restriction made based on their clinical diagnosis. A total of 442 children {55.7% boys, 40.3% probands, median age: 8.0 [interquartile range (IQR) 9.5] years} from 350 families were included; 67.9% were asymptomatic at diagnosis. Four main phenotypes were identified: isolated progressive cardiac conduction disorders (25.6%), overlap phenotype (15.6%), isolated long QT syndrome type 3 (10.6%), and isolated Brugada syndrome type 1 (1.8%); 44.3% had a negative electrocardiogram phenotype. During a median follow-up of 5.9 (IQR 5.9) years, 272 cardiac events (CEs) occurred in 139 (31.5%) patients. Patients whose mutation localized in the C-terminus had a lower risk. Compound genotype, both gain- and loss-of-function SCN5A mutation, age ≤ 1 year at diagnosis in probands and age ≤ 1 year at diagnosis in non-probands were independent predictors of CE. Conclusion In this large paediatric cohort of SCN5A mutation-positive subjects, cardiac conduction disorders were the most prevalent phenotype; CEs occurred in about one-third of genotype-positive children, and several independent risk factors were identified, including age ≤ 1 year at diagnosis, compound mutation, and mutation with both gain- and loss-of-function.

BACKGROUND Concealed left-sided accessory pathways (CLAP) are a cause of supraventricular tachycardia (SVT) in the young. Most are mapped with right ventricular (RV) apical/outflow pacing. Rarely, alternative means of mapping are required. We review our experience from three pediatric electrophysiology (EP) centers with a rare form of "hidden" CLAP. METHODS All patients

Background: Supraventricular tachycardia is common after heart transplantation. Adenosine, the standard therapy for treating supraventricular tachycardia in children and adults without transplantation, is relatively contraindicated after transplantation because of a presumed risk of prolonged atrioventricular block in denervated hearts. This study tested whether adenosine caused prolonged asystole after transplantation and if it was effective in blocking atrioventricular nodal conduction in these patients. Methods: This was a single-center prospective clinical study including healthy heart transplant recipients 6 months to 25 years of age presenting for routine cardiac catheterization during 2015 to 2016. After catheterization, a transvenous pacing catheter was placed and adenosine was given following a dose-escalation protocol until atrioventricular block was achieved. The incidence of clinically significant asystole (≥12 seconds after adenosine) was quantified. The effects of patient characteristics on adenosine dose required to produce atrioventricular block and duration of effect were also measured. Results: Eighty patients completed adenosine testing. No patient (0%; 95% confidence interval, 0–3) required rescue ventricular pacing. Atrioventricular block was observed in 77 patients (96%; 95% confidence interval, 89–99). The median longest atrioventricular block was 1.9 seconds (interquartile range, 1.4–3.2 seconds), with a mean duration of adenosine effect of 4.3±2.0 seconds. No patient characteristic significantly predicted the adenosine dose to produce atrioventricular block or duration of effect. Results were similar across patient weight categories. Conclusions: Adenosine induces atrioventricular block in healthy pediatric and young adult heart transplant recipients with minimal risk when low initial doses are used (25 μg/kg; 1.5 mg if ≥60 kg) and therapy is gradually escalated. Clinical Trial Registration: URL: http://www.clinicaltrials.gov . Unique identifier: NCT02462941.

Background Radiofrequency catheter ablations of anteroseptal (AS) accessory pathways (AP) in pediatric patients have higher incidence of atrioventricular (AV) block than other AP locations. We report our experience using cryoablation in pediatric patients where a His bundle electrogram was noted on the ablation catheter at the site of the successful ablation. Methods and Results We retrospectively reviewed all patients ≤21 years that underwent cryoablation for an AS AP from 2005 to 2012 at our institution (n=70). Patients with a His bundle electrogram noted on the cryoablation catheter at the location of the successful lesion were identified (n=6, 8.5%). All six patients had ventricular preexcitation. Median age of 15.9 years (7.2 - 18.2). AV nodal function was monitored during the cryoablation with intermittent rapid atrial pacing conducted through the AV node (n=2), with atrial extra-stimulus testing (n=2), or during orthodromic reentrant tachycardia (n=2). Acute success occurred in all patients. Two patients had early recurrence of AP conduction. Both patients underwent a second successful cryoablation, again with a His bundle electrogram on the cryoablation catheter. At a median follow-up of 13 months (3 to 37 months) there was no recurrence of accessory pathway conduction and AVN function was normal. Conclusions In a small number of pediatric patients with AS AP with a His bundle electrogram seen on the ablation catheter, the use of cryotherapy was safe and effective for elimination of AP conduction without impairment of AV nodal conduction.