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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.

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.

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 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.

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.

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.

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.

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.

Surgical repair for atrial septal defects (ASD) generally occurs during childhood. Post-pericardiotomy syndrome (PPS) after cardiac surgery has a reported incidence of 1–40 %. We focused exclusively on secundum ASD repair to evaluate the incidence of PPS. The purpose of this study is to determine the incidence of PPS after surgical repair of secundum ASD and investigate what risk factors may be predictive of its development. A retrospective study was performed, and 97 patients who underwent surgical closure of a secundum ASD were identified. 27 (28 %) were diagnosed with PPS within the first postoperative year. Diagnosis was made if they had evidence of new or worsening pericardial effusion and the presence of ≥2 of the following criteria: fever >72 h postoperatively, irritability, pleuritic chest pain, or pericardial friction rub. Closure of secundum ASDs was performed at a median age of 3.8 years (Interquartile Range (IQR): 2.2–6.0 years) and a median weight of 14.3 kilograms (IQR: 10.9–19.3 kilograms). The median time for development of PPS was 8 days post-op (IQR: 5–14). Significantly, 19 (27 %) of 70 patients in the non-PPS group had a small pericardial effusion on their discharge echocardiogram, while of the 27 patients who developed PPS, 17 (63 %) had a small pericardial effusion on their discharge echocardiogram (p = 0.001). PPS is relatively common following surgical closure of secundum ASDs. A small pericardial effusion on discharge echocardiogram is predictive of development of PPS postoperatively. In patients who develop PPS, there is a good response to therapy with a benign course.

It has been reported that the presence of intermittent pre-excitation indicates low risk of rapid conduction via the accessory pathway in atrial fibrillation. We report a case of a 10-year-old boy with a history of intermittent pre-excitation who presented with atrial fibrillation with very rapid conduction.

Prolongation of the QT interval and development of torsades de pointes are known in patients with complete heart block and profound bradycardia. We report the case of a patient with complete heart block and torsades, with long QT seen during a period of junctional tachycardia at a rate faster than the minimum pacemaker rate.

Background Transtelephonic monitoring (TTM) of pediatric patients with cardiac pacemakers (PMs) has been shown to have high sensitivity and specificity in identifying PM malfunction. The objective of this study is to determine if there is a difference in the rate of abnormal TTM findings in transvenous versus epicardial PM systems. Methods Our TTM database was reviewed. Patients younger than 21 years of age enrolled for TTM between 1990 and 2010 were included. The abnormal TTM recordings (not including elective replacement indicator) were identified. Logistic regression was used for statistical analysis. Note that P < 0.05 was considered significant. Results We identified 186 patients. There were 75 (40%) epicardial systems. The mean age at TTM enrollment was 6.8 ± 5.9 years (2 months–20.2 years). There were 41 (22%) patients with abnormal TTM findings. The abnormalities were found in 23/75 (31%) epicardial and 18/111 (16%) transvenous systems (odds ratio [OR]: 2.3, 95% confidence interval [CI]: 1.13–4.62, P = 0.02). When controlling for age and presence of heart disease the OR for abnormal transmission in epicardial systems compared with transvenous was 2.1 (95% CI: 1.03–4.43, P = 0.04). Patients with epicardial systems were more likely to have capture abnormalities on TTM than transvenous systems (OR: 6.1, 95% CI: 1.9–19.5, P = 0.002). Conclusion Pediatric patients with epicardial PM systems are more likely to have abnormal TTM test (particularly capture problems) than patients with transvenous systems regardless of age or presence of heart disease. Consequently, patients with epicardial PM systems should be followed closely with TTM.

Left Ventricular Tachycardia in PediatricsIntroduction The aim of this study was to evaluate the clinical presentation and outcomes of pediatric patients with ventricular tachycardia (VT) originating from left heart structures. Methods and Results This international multicenter retrospective study including 152 patients (age 10.0 ± 5.1 years, 62% male), divided into those with fascicular VT (85%, 129/152) and nonfascicular LV VT (15%, 23/152). All patients had a normal heart structure or only a minor cardiac abnormality. Adenosine was largely ineffective in both groups (tachycardia termination in 4/74 of fascicular VT and 0/5 of nonfascicular LV VT). In fascicular VT, calcium channel blockers were effective in 80% (74/92); however, when administered orally, there was a 21% (13/62) recurrence rate. In nonfascicular LV VT, a variety of antiarrhythmic therapies were used with no one predominating. Ablation procedures were successful in 71% (72/102) of fascicular VT and 67% (12/18) of nonfascicular LV VT on an intention to treat analysis. Major complications occurred in 5 patients with fascicular VT and 1 patient with nonfascicular LV VT. After a follow-up period of 2 years (1 day to 15 years), 72% of all patients with fascicular VT were off medications with no tachycardia recurrence. One patient died of noncardiac causes. In nonfascicular LV VT, follow-up was 3.5 years (0.5–15 years), P = 0.38. A total of 65% of these patients were free from arrhythmias. Two patients died suddenly (P < 0.01). Conclusion The clinical course and outcomes of pediatric patients with fascicular VT and nonfascicular LV VT are varied. Catheter ablation procedures can be curative.

Infantile hemangiomas (IHs) are common neoplasms composed of proliferating endothelial-like cells. Despite the relative frequency of IH and the potential severity of complications, there are currently no uniform guidelines for treatment. Although propranolol has rapidly been adopted, there is significant uncertainty and divergence of opinion regarding safety monitoring, dose escalation, and its use in PHACE syndrome (PHACE = posterior fossa, hemangioma, arterial lesions, cardiac abnormalities, eye abnormalities; a cutaneous neurovascular syndrome characterized by large, segmental hemangiomas of the head and neck along with congenital anomalies of the brain, heart, eyes and/or chest wall). A consensus conference was held on December 9, 2011. The multidisciplinary team reviewed existing data on the pharmacologic properties of propranolol and all published reports pertaining to the use of propranolol in pediatric patients. Workgroups were assigned specific topics to propose protocols on the following subjects: contraindications, special populations, pretreatment evaluation, dose escalation, and monitoring. Consensus protocols were recorded during the meeting and refined after the meeting. When appropriate, protocol clarifications and revision were made and agreed upon by the group via teleconference. Because of the absence of high-quality clinical research data, evidence-based recommendations are not possible at present. However, the team agreed on a number of recommendations that arose from a review of existing evidence, including when to treat complicated IH; contraindications and pretreatment evaluation protocols; propranolol use in PHACE syndrome; formulation, target dose, and frequency of propranolol; initiation of propranolol in infants; cardiovascular monitoring; ongoing monitoring; and prevention of hypoglycemia. Where there was considerable controversy, the more conservative approach was selected. We acknowledge that the recommendations are conservative in nature and anticipate that they will be revised as more data are made available. Pediatrics 2013;131:128-140

International audience; Unlabelled - Atrioventricular block is classified as congenital if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental passage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive cardiac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe permanent cardiac pacing in almost all patients, including those with structural heart abnormalities. Conclusion - Early diagnosis and appropriate management are critical in many cases in order to prevent sudden death, and this review critically assesses our current understanding of the pathogenetic mechanisms, clinical course, and optimal management of congenital and childhood AV block. What is known - • Prevalence of congenital heart block of 1 per 15,000 to 20,000 live births. AV block is defined as congenital if diagnosed in utero, at birth, or within the first month of life, whereas childhood AV block is diagnosed between the first month and the 18th year of life. As a result of several different etiologies, congenital and childhood atrioventricular block may occur in an entirely structurally normal heart or in association with concomitant congenital heart disease. Cardiac pacing is indicated in symptomatic patients and has several prophylactic indications in asymptomatic patients to prevent sudden death. • Autoimmune, congenital AV block is associated with a high neonatal mortality rate and development of dilated cardiomyopathy in 5 to 30 % cases. What is New: • Several genes including SCN5A have been implicated in autosomal dominant forms of familial progressive cardiac conduction disorders. • Leadless pacemaker technology and gene therapy for biological pacing are promising research fields. In utero percutaneous pacing appears to be at high risk and needs further development before it can be adopted into routine clinical practice. Cardiac resynchronization therapy is of proven value in case of pacing-induced cardiomyopathy.

Background Antidromic reciprocating tachycardia (ART) is a rare form of wide complex tachycardia in children with Wolff-Parkinson-White syndrome (WPW). The incidence and electrophysiologic characteristics of ART in children with WPW have not been well described. Methods A multicenter retrospective analysis of all patients with WPW undergoing electrophysiology (EP) study from 1990 to 2009 was performed. Patients with clinical or inducible ART were included. Results A total of 1,147 patients with WPW underwent EP study and 30 patients had ART (2.6%) and were the subject of this analysis. The mean age was 16±3 years, weight was 65±16 kg, and tachycardia cycle length was 305±55 ms. There were two patients (7%) with congenital heart disease (both with Ebstein's anomaly). Four patients (13%) had more than one accessory pathway (AP). The location of the AP was left sided in 53% of patients and right sided in 47%, with septal location and left lateral pathways most commonly involved. AP conduction was found to be high risk in 17 patients (57%). Ablation was not attempted in two patients (7%) due to proximity to the HIS and risk of heart block. Ablation was acutely successful in 93% of the patients in whom it was attempted. Conclusions ART is a rare finding in children undergoing EP study. Over half of the patients with ART were found to be high risk and multiple AP were uncommon. Unlike the adult population, ART occurred commonly with septal APs.

Remifentanil is commonly used during anesthesia in pediatric electrophysiologic studies (EPS). The purpose of this study is to determine the effects of remifentanil on the cardiac electrophysiologic properties of children undergoing ablation of supraventricular tachycardia (SVT). A prospective study was performed in patients undergoing EPS before ablation of SVT. Each patient received two different anesthetic protocols: protocol 1 = propofol (200 mcg/kg/min) and protocol 2 = propofol (120 mcg/kg/min) plus remifentanil (0.3 mcg/kg/min). EPS data were measured during the steady state of each protocol. Paired Student t test was performed for analysis of continuous data. All p values

A 16-year-old female patient with Wolff-Parkinson-White syndrome and supraventricular tachycardia underwent radiofrequency (RF) catheter ablation of an accessory pathway in the left lateral area. During RF ablation she developed reversible ST segment elevation secondary to coronary artery spasm. Coronary angiography demonstrated the ablation catheter in close proximity to the circumflex coronary artery, with no evidence of coronary artery injury. Subsequently, conduction by way of the accessory pathway was successfully eliminated with cryoablation with no further coronary spasm or injury.

Direct-current cardioversion is a common treatment modality for acute termination of atrial flutter in neonates. Studies in children have demonstrated that cardioversion is often successful with as little as 0.25-0.5 J/kg with the current biphasic devices. We hypothesize that during cardioversion of atrial flutter in neonates, however, the impedance may be high and more energy may be required for successful cardioversion. A retrospective chart review of our institutional experience from 2005 through 2008 was performed. Neonates with atrial flutter requiring cardioversion who had strips available for review were included. Six patients met the inclusion criteria. The median age at the time of cardioversion was 2.6 h (range, 1.3-336 h) and the mean weight was 3.22 +/- 0.4 kg (SD). The mean electrical impedance of the successful shocks was elevated, at 234 +/- 136 Omega. The mean energy delivered for successful cardioversion was 0.9 +/- 0.3 J/kg, and the current was 1 A in all patients. In conclusion, the shock impedance was elevated in the neonates studied during cardioversion of atrial flutter. Low current was sufficient for successful cardioversion. Further studies are needed in this specific population.

Objectives To determine the outcomes of medical management, pacing, and catheter ablation for the treatment of nonpost-operative junctional ectopic tachycardia (JET) in a pediatric population. Background Nonpost-operative JET is a rare tachyarrhythmia that is associated with a high rate of morbidity and mortality. Most reports of clinical outcomes were published before the routine use of amiodarone or ablation therapies. Methods This is an international, multicenter retrospective outcome study of pediatric patients treated for nonpost-operative JET. Results A total of 94 patients with JET and 5 patients with accelerated junctional rhythm (age 0.8 year, range fetus to 16 years) from 22 institutions were identified. JET patients presenting at age ≤6 months were more likely to have incessant JET and to have faster JET rates. Antiarrhythmic medications were utilized in a majority of JET patients (89%), and of those, amiodarone was the most commonly reported effective agent (60%). Radiofrequency ablation was conducted in 17 patients and cryoablation in 27, with comparable success rates (82% radiofrequency vs. 85% cryoablation, p = 1.0). Atrioventricular junction ablation was required in 3% and pacemaker implantation in 14%. There were 4 (4%) deaths, all in patients presenting at age ≤6 months. Conclusions Patients with nonpost-operative JET have a wide range of clinical presentations, with younger patients demonstrating higher morbidity and mortality. With current medical, ablative, and device therapies, the majority of patients have a good clinical outcome.

Background The traditional first stage of palliation for functional single-ventricle lesions with transposition of the great vessels and systemic outflow tract obstruction has been either the Norwood or Sano procedure or the Damus-Kaye-Stansel procedure. There is limited literature on the use of an arterial switch procedure as the initial staged palliation for functional single ventricles in this setting. This study is an examination of our institutional experience with performing the palliative switch procedure with examination of suitability for Fontan completion and midterm outcome in these patients. Methods This is a retrospective review of our institutional experience from October 1991 through August 2006 on single-ventricle patients with transposition of the great vessels and systemic outflow tract obstruction who underwent a palliative arterial switch procedure. Results Nine patients underwent an initial palliative switch procedure. Six of 9 patients underwent completion of palliation with the Fontan procedure and are alive and well. One patient is well and is awaiting the next stage of palliation (78%). There was 1 early operative death (11%) and 1 late death (11%). There was 1 case of recoarctation (11%). Conclusions The palliative switch procedure appears a reasonable surgical option for patients with functional single-ventricle lesions, transposition of the great vessels, and systemic outflow tract obstruction. Patients who have undergone a palliative switch procedure are suitable candidates for completion of palliation with the Fontan procedure.

Carditis is a common manifestation of adult patients with Lyme disease affecting 4-10% of Lyme patients in the United States. However, children with Lyme disease rarely present with acute carditis. The management of pediatric patients with complete heart block (CHB) secondary to Lyme carditis has not been well described. We report the acute management of 2 pediatric patients that presented in CHB secondary to Lyme disease.

Late onset of complete heart block is a potentially dangerous complication after open heart surgery for congenital heart disease. The characteristics of patients with late-onset heart block have not been well described. A retrospective review of a pacemaker database was done to identify patients who presented with new onset heart block between 1988 and 2006, after they had been discharged from the hospital after open heart surgery with normal AV conduction. Fifteen patients were identified. The age at the time of the last surgery before the onset of heart block was 2.0 +/- 3.2 years (range: 3 days to 10 years). Nine had a ventricular septal defect repair, four had an atrioventricular canal, and two other patients had other types of heart defect. The last EKG available for analysis before the onset of heart block had been obtained 5.1 +/- 6.5 years (range: 7 days to 16 years) after surgery. The symptoms at the time of presentation were variable. Four patients presented with fatigue or exercise intolerance, two with syncope, two with congestive heart failure, and one with irritability, and the remaining six patients were diagnosed during routine follow-up. The time between open heart surgery and placement of a permanent pacemaker was 6.8 +/- 7.3 years (range: 2 months to 19 years). There were seven patients in whom the onset of heart block was more than 6 years after surgery. Late onset of complete heart block after open heart surgery could be dangerous when presenting without warning. These data would support the notion that patients should be followed for life after repair of congenital heart defects, with special attention to the conduction system, particularly after repair of septal defects.

The two main theories regarding the pathogenesis of coarctation of the aorta are the Skodaic hypothesis of ductal tissue constricting the aorta at the level of the insertion of the ductus arteriosus and the flow theory of decreased ascending aortic blood flow in the fetus, which results in associated isthmic narrowing and a localized shelf. To document that ectopic ductal tissue constriction can cause coarctation of the aorta in the absence of a patent ductus arteriosus, we report three cases of infants presenting with critical coarctation who responded to prostaglandin E1 infusion without opening the ductus arteriosus.

Background: First-line therapy for children with attention-deficit–hyperactivity disorder (ADHD) is stimulant medication, which may have potential cardiovascular side-effects. In patients with supraventricular tachycardia or Wolf-Parkinson-White syndrome (WPW), therapy for ADHD could become challenging. The purpose of the present study was to review the authors' experience of performing electrophysiologic study (EPS) with or without ablation to determine how it affected ADHD therapy. Methods: Retrospective chart review of patients who underwent EPS between 2002 and 2009 was carried out. All patients under 21 years of age who had prior diagnosis of ADHD were included. Results: Twenty patients met the inclusion criteria. The mean age was 12.1 ± 2.7 years (range: 5.6–16.8 years). The patients were diagnosed with ADHD on average 3.9 ± 2.7 years (range: 6 months–9 years) prior to the EPS. All patients had a structurally normal heart. Sixteen patients had cardiac symptoms. Seventeen patients underwent ablation of the arrhythmia substrate (16/17, 94% successful). Three patients with asymptomatic WPW were at low risk for life-threatening arrhythmias and did not have ablation. After the EPS, two patients had increased doses of their ADHD medications, and two patients whose health-care providers stopped the stimulant medication prior to EPS because of recurrent tachycardia were restarted on medications. All other patients on ADHD medications continued therapy. Conclusions: EPS for risk stratification and ablation of arrhythmia substrate is safe and effective, allowing more liberal therapy in patients with ADHD and supraventricular tachycardia or WPW.

Hypoplastic left heart syndrome (HLHS) is a severe form of congenital heart disease characterized by underdevelopment of the left heart. There has been no previously defined "classic" ECG pattern in a large homogenous population of patients with HLHS. We performed a retrospective review of ECGs from neonates with HLHS from 2001 to 2011 with electrocardiograms available prior to surgical intervention. Eighty-nine neonates met the inclusion criteria and were compared to a control population. HLHS patients had a longer PR interval 108 ± 18 versus 98 ± 11 ms (p < 0.05), a wider QRS complex 84 ± 17 versus 54 ± 5 ms (p < 0.05), lower voltage S waves in V1 2.0 ± 3.3 versus 5.8 ± 4.6 mm (p < 0.001) or absent S waves in V1 52 versus 4 % (p < 0.001) and lower voltage R waves in V6 7.8 ± 4.8 versus 9.3 ± 4.2 mm (p < 0.05). Patients with HLHS were more likely to have absent Q waves in the lateral precordial leads 78 versus 0 % (p < 0.001) and inferior leads 20 versus 1 % (p < 0.001) and an abnormal frontal plane QRS axis 26 versus 11 % (p < 0.05). HLHS patients were more likely to have a preexcited appearance 11 versus 0 % (p = 0.001). Despite these findings, 20 % of patients with HLHS had a normal ECG. Compared to age-matched controls, patients with HLHS were more likely to exhibit a longer PR interval, a wider QRS complex, decreased left-sided forces, an absence of septal Q waves in the inferior and lateral leads, an abnormal frontal plane QRS axis and a preexcited appearance.

Myocarditis in children can result in significant morbidity and mortality, yet limited prognostic data exist. The aim of this study was to test the hypothesis that pediatric patients with arrhythmias during hospitalization for acute myocarditis have worse outcomes and increased resource utilization. A retrospective study using the Pediatric Health Information System database was performed to examine the effects of clinically significant arrhythmias on in-hospital mortality, length of stay, and costs per day. Data were obtained for children ≤18 years of age, discharged from January 1, 2004 to March 31, 2013, with a diagnosis of myocarditis. Clinically significant tachyarrhythmia was defined as supraventricular tachycardia, atrial fibrillation or flutter, or ventricular tachycardia or fibrillation in patients receiving antiarrhythmic medications or cardioversion. Clinically significant bradyarrhythmia was defined as second-degree, complete, or other heart block for which a pacemaker was placed. Multivariable analyses were performed. A total of 2,041 subjects with myocarditis were identified. Tachyarrhythmias were reported in 234 (11.5%) and bradyarrhythmias in 22 (1.1%). Overall mortality was 8.7%. In multivariable analyses, after considering the effects of gender, age at admission, geographic region, year and month of admission, presence of congenital heart disease or an identified virus, and use of steroids, nonsteroidal anti-inflammatories, or inotropes, and after controlling for clustering by institution, tachyarrhythmias were associated with a 2.3 times increase in the odds of mortality (95% confidence interval 1.6 to 3.3, p0.001), a 58% increase in length of stay (95% confidence interval 38% to 82%, p0.001), and a 28% increase in costs per day (95% confidence interval 15% to 43%, p0.001). Bradyarrhythmia was not associated with mortality, length of stay, or costs per day. In conclusion, tachyarrhythmias are associated with significant increases in mortality and resource utilization in children with myocarditis.

Background . The two major surgical approaches to the relief of bulboventricular foramen (BVF) obstruction in patients with single left ventricle (LV) are the Damus-Kaye-Stansel (DKS) procedure or direct BVF resection. Theoretical advantages of the DKS include better outflow gradient relief, lower potential incidences of postoperative heart block and lower incidences of reoperation. Potential disadvantages of this approach include increased semilunar valvar insufficiency, lack of feasibility when attempting septation-type operations for univentricular hearts, and a technically more difficult operation. We report the results of direct surgical BVF resection. Methods . From June 1990 to June 1999, 9 patients had direct BVF resection performed at our institution. The median age at surgery was 16.5 years (range 1 month to 27 years). Diagnoses in these patients were {S,L,L} single LV (n = 8) and {S,D,D} single LV tricuspid atresia (n = 1). Eight of 9 patients had pulmonary artery bands placed either before BVF resection or at the same time as this procedure. Three patients required reoperation for reobstruction at the BVF (12 total operations in 9 patients). Results . Median preoperative peak systolic gradient across the BVF measured at cardiac catheterization was 47 mm Hg (range 10 to 63 mm Hg). The median peak gradient measured by Doppler echocardiography was 44 mm Hg (range 5 to 125 mm Hg). Eight of 9 patients survived the operation to discharge from the hospital and 7 of 9 are alive at follow-up. At a median follow-up of 22 months (range 5 to 76 months), 8 of 8 surviving patients had an unobstructed BVF as determined by qualitative two-dimensional echocardiography and Doppler color flow imaging. There was one perioperative and one late death 5 months postoperatively (secondary to fungal sepsis). No patient developed new or worsened aortic insufficiency after BVF resection. Eight of 9 patients had no change in AV nodal conduction after surgery. One patient developed Mobitz II heart block requiring postoperative implantation of a pacemaker. Conclusions . Direct resection of an obstructive BVF can be performed with total relief of obstruction although reoperation may be required. Atrioventricular nodal function can be preserved in most patients with this operative approach, including those with {S,L,L} segmental anatomy.

Intravenous diltiazem was administered to 10 pediatric patients with primary atrial tachyarrhythmias with rapid ventricular response. Rapid, consistent, and safe temporary ventricular rate control was obtained in all patients given this medication.

We report the case of a 19-year-old female who developed recurrent dizziness and syncope 2 years after cardiac transplant. During a pre-syncopal episode, a loop monitor revealed paroxysmal atrio-ventricular block (PAVB). The placement of a permanent transvenous pacemaker led to the resolution of her symptoms. In this report, we discuss the causes of PAVB, review the literature on PAVB in heart transplant patients, examine the electrophysiology of PAVB, and consider additional causes of PAVB in pediatric transplant patients.

We report a case of an infant who developed transient complete heart block following aortic and mitral valve surgery. In the course of his recovery, he developed a variable morphology wide complex rhythm with intermittent narrow complex beats. Review of his initial postoperative electrocardiogram (ECG), which demonstrated a right bundle branch block, helped to clarify the rhythm.

Epicardial pacing is frequently used in pediatric patients with congenital heart disease. Automatic threshold determination has been reported to be safe in epicardial lead systems. We report a case of falsely low ventricular thresholds determined by automatic capture verification in a patient with complete loss of capture due to a lead fracture.

Background— Studies of the arterial switch operation for Taussig–Bing anomaly demonstrate significant rates of reintervention and mortality, particularly after initial palliation to delay complete repair. We aimed to describe the long-term outcomes of our 21-year practice of single-stage arterial switch operation for all patients with Taussig–Bing anomaly. Methods and Results— A retrospective study was performed, and 43 patients with Taussig–Bing anomaly were identified between 1990 and 2011. Median age at arterial switch operation was 7 (range, 2–192) days, and median operative weight was 3.2 (1.4–6.2) kg. Aortic arch obstruction was present in 30 patients (70%). Hospital mortality was 7% (n=3). Follow-up was available for 37 hospital survivors at a mean of 8.1 (±6.3) years. Late mortality was 2% (n=1). At follow-up, all patients were in New York Heart Association functional class I. Freedom from transcatheter or surgical reintervention was 73% at 1 year, 64% at 5 years, and 60% at 10 years. Eleven patients underwent 13 catheter reinterventions on the pulmonary arteries (n=8) or aortic arch (n=5). Seven patients underwent 11 reoperations, including relief of right ventricular outflow tract obstruction (n=5), pulmonary arterioplasty (n=3), recoarctation repair (n=2), and tricuspid valve repair (n=1). By multivariate analysis, a preoperative aortic valve annulus z score of ≤−2.5 was associated with reintervention (hazard ratio, 7.66 [95% confidence interval, 1.29–45.6], P =0.03). Conclusions— Although reintervention is common, primary correction of Taussig–Bing anomaly with arterial switch operation can be achieved in all patients with low mortality and good long-term outcomes.

Isoproterenol (ISO) testing following radiofrequency catheter ablation (RFCA) of accessory pathways (APs) in children is often performed to assess efficacy. However, its role in postablative testing for this indication has not been previously studied. In view of a recent national shortage of ISO, this study reviewed the results of ISO testing in pediatric patients after acutely successful RFCA to evaluate its role in postablative testing. Seventy patients (median age 13.0 years, range 2.8-24 years) underwent acutely successful RFCA for APs. If AP conduction was not present and tachycardia was not inducible with programmed stimulation 30 minutes following RFCA, repeat testing was performed during continuous infusion ISO. ISO infusion resulted in the induction of arrhythmias in 3 (4%) of 70 patients that required further ablative therapy. None of these patients had inducible arrhythmias or AP conduction during postablative testing without ISO infusion. One patient, with the permanent form of junctional reciprocating tachycardia (PJRT), had persistence of AP conduction requiring further RFCA applications. Two patients had inducible AV nodal reentrant tachycardia (AVNRT) that was treated with slow pathway modification. At a median follow-up of 7.3 months, two (3%) patients had recurrence of tachycardia. These patients did not have inducible tachycardia, AP conduction, or dual AVN physiology with ISO testing. Although ISO may improve AP conduction in patients with PJRT and uncover AVNRT, these results suggest that ISO testing after an apparently successful AP ablation may not be necessary to confirm acute success. In addition, lack of AP conduction on ISO did not rule out the possibility of medium-term recurrence.

Objective To determine if pediatric patients with a history of lone atrial fibrillation (AF) have other forms of supraventricular tachycardia (SVT) that may potentially trigger AF. Study design A multicenter review of patients with lone AF who underwent electrophysiology (EP) study from 2006-2011 was performed. Inclusion criteria: age ≤21 years, normal ventricular function, structurally normal heart, history of AF, and EP study and/or ablation performed. Exclusion criteria: congenital heart disease or cardiomyopathy. Patient demographics, findings at EP study and follow-up data were recorded. Results Eighteen patients met inclusion criteria. The mean age was 17.9 ± 2.2 years, weight was 82 ± 21 kg, body mass index was 27 ± 6, and 15 (83%) were males. Eleven (61%) were overweight or obese. Seven (39%) had inducible SVT during EP study: 5 atrioventricular nodal re-entry tachycardia (71%) and 2 concealed accessory pathways with inducible atrioventricular re-entry tachycardia (29%). All 7 patients with inducible SVT underwent radiofrequency ablation. There were no complications during EP study and/or ablation for all 18 patients. The mean follow-up was 1.7 ± 1.5 years and there were no recurrences in the 7 patients who underwent ablation. There were 2 recurrences of AF in patients with no other form of SVT during EP study. Conclusions Inducible SVT was found in 39% of pediatric patients undergoing EP study for lone AF. EP study should be considered for pediatric patients presenting with lone AF.