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To characterize the prevalence, associations, management, and outcomes of supraventricular tachycardia (SVT) in neonates with congenital diaphragmatic hernia (CDH).Retrospective chart and cardiology code review within a cohort of patients with CDH was used to define a subpopulation with atrial arrhythmia. SVT mechanisms were confirmed by electrocardiogram analysis. Cox proportional hazard regression identified risk factors for SVT and association with clinical outcomes.Medical Surgical ICU in a single, tertiary center, Boston Children's Hospital.Eligible patients included neonates presenting with classic Bochdalek posterolateral CDH between 2005 and 2017, excluding newborns with Morgagni hernia or late diagnoses of CDH (28 d).None.SVT arose in 25 of 232 neonates with CDH, (11%); 14 of 25 infants (56%) had recurrent SVT; atrioventricular node-dependent tachycardia was the most frequent mechanism (32%). The majority (71%) of SVT episodes received intervention. Nine patients (36%) received preventative antiarrhythmic medications. SVT was associated with lower Apgar score at 1 min, structural heart disease, larger defect size, extracorporeal membrane oxygenation (ECMO) support, and prostaglandin therapy for ductal patency as well as hospital stay greater than or equal to 8 weeks and use of supplemental oxygen at discharge.SVT can occur in neonates with CDH and frequently requires treatment. Odds of occurrence are increased with greater CDH disease severity, ECMO, and prostaglandin use. In unadjusted logistic regression analysis, SVT was associated with adverse hospital outcomes, underscoring the importance of recognition and management in this vulnerable population.

Altered ventricular depolarization due to manifest accessory pathway conduction (ie, Wolff-Parkinson-White syndrome) leads to repolarization abnormalities that persist after pathway ablation. The term T-wave memory (TWM) has been applied to these changes, as the postablation T-wave vector "remembers" the pre-excited QRS vector. In adults, these abnormalities can be misinterpreted as ischemia leading to unnecessary interventions. To date, no comprehensive studies have evaluated this phenomenon in the pediatric population.The purpose of this study was to define TWM in the pediatric population, identify preablation risk factors, and delineate the timeline of recovery.Pre- and postablation electrocardiograms (ECGs) in patients ≤25 years were analyzed over a 5-year period. Frontal plane QTc interval, T-wave axis, QRST angle, and T-wave inversions were used to identify patients with TWM. Univariate analysis was performed to determine the association of preablation ECG features with the outcome of TWM.TWM was present in 42% of pediatric patients, with resolution occurring within 3 months of ablation. Preablation QRS axis0° was a strong predictor of TWM (odds ratio [OR] 15.2; 95% confidence interval [CI] 5.7-40), followed by posteroseptal pathway location (right posteroseptal-OR 8.9; 95% CI 4.2-18.8; left posteroseptal-OR 6.1; 95% CI 1.7-22.3). The degree of pre-excitation had a modest association with the development of TWM. No adverse events were observed.TWM is less common in children compared to adults, and normalization occurred within 3 months postablation. The most predictive features for the development of TWM include a leftward pre-excited QRS axis and posteroseptal pathway location.

Decreased physical activity is associated with cardiovascular, metabolic and mental health disease. While decreases in physical activity during the COVID-19 pandemic have been described in the general population, there is a paucity of data regarding children with underlying cardiovascular disease. We hypothesized there would be a decrease in physical activity at the onset of the COVID-19 pandemic. Performed a single-center, retrospective cohort study of children aged 80% of dates from February 3, 2020 through June 30, 2020. Patients with significant neurologic/neuromuscular disease were excluded. We identified 144 patients with a median age of 15.4 years. 47% were female. 34% had congenital heart disease, 20% had cardiomyopathy, 19% had an inherited arrhythmia syndrome and 5% had atrioventricular block without congenital heart disease. 47% of patients had an implantable loop recorder, 29% had a permanent pacemaker and 24% had an implantable cardioverter-defibrillator. We observed a significant decrease in device-measured physical activity from baseline (February 3–March 9), with up to a 21% decrease in physical activity during mid-March through early May. Activity levels returned to pre-pandemic levels in June. Physical activity sharply declined in children with cardiac rhythm management devices at the onset of the COVID-19 pandemic. These data highlight the importance of finding strategies to maintain physical activity during the current pandemic and future public health crises.

Catheter ablation of accessory pathways (APs) in Ebstein anomaly (EA) has been associated with a high recurrence risk.The purpose of this study was to compare outcomes of AP ablation in EA in an early (1990-2004) vs a recent (2005-2019) era and identify variables associated with recurrence.A retrospective review of all catheter ablations for supraventricular tachycardia in EA at our institution was performed.We identified 76 patients with median (25th-75th quartiles) age 9 (2.6-13.3) years. Of these patients, 52 had AP alone, 12 had atrial flutter, 3 had atrioventricular nodal reentrant tachycardia, and 9 had AP plus at least 1 additional arrhythmia. Of the 61 patients with APs, a total of 78 separate APs were identified: 40 right-sided, 37 septal, and 1 left-sided. Acute success for AP first procedure was 89% and did not differ between early and recent eras (89% vs 88%; P = .48). However, 19 patients (31%) required repeat procedures (average 1.4 per patient) due to AP recurrence or ablation failure at first attempt. In comparison to early era, recent era ablations had significantly lower recurrence rates at 1 year (62% vs 19%; P = .005). At median follow-up of 2.5 (0.2-7) years, ultimate AP elimination after all procedures was 93%. Younger age at time of electrophysiological study (2 vs 12-47 years: hazard ratio [HR] 7.3; P = .003) and ablation era (early era vs recent era: HR 3.65; P = .009) predicted recurrence.Outcomes for AP ablation in patients with EA have improved, but there is still a relatedly high recurrence risk requiring repeat procedures.

Introduction:Reflex-mediated syncope occurs in 15% of children and young adults. In rare instances, pacemakers are required to treat syncopal episodes associated with transient sinus pauses or atrioventricular block. This study describes a single centre experience in the use of permanent pacemakers to treat syncope in children and young adults.Materials and methods:Patients with significant pre-syncope or syncope and pacemaker implantation from 1978 to 2018 were reviewed. Data collected included the age of presentation, method of diagnosis, underlying rhythm disturbance, age at implant, type of pacemaker implanted, procedural complications and subsequent symptoms.Results:Fifty patients were identified. Median age at time of the first syncopal episode was 10.2 (range 0.3–20.4) years, with a median implant age of 14.9 (0.9–34.3) years. Significant sinus bradycardia/pauses were the predominant reason for pacemaker implant (54%), followed by high-grade atrioventricular block (30%). Four (8%) patients had both sinus pauses and atrioventricular block documented. The majority of patients had dual-chamber pacemakers implanted (58%), followed by ventricular pacemakers (38%). Median follow-up was 6.7 (0.4–33.0) years. Post-implant, 4 (8%) patients continued to have syncope, 7 (14%) had complete resolution of their symptoms, and the remaining reported a decrease in their pre-syncopal episodes and no further syncope. Twelve (24%) patients had complications, including two infections and eight lead malfunctions.Conclusions:Paediatric patients with reflex-mediated syncope can be treated with pacing. Complication rates are high (24%); as such, permanent pacemakers should be reserved only for those in whom asystole from sinus pauses or atrioventricular block has been well documented.

Risk stratification is required to set an exercise prescription for cardiac rehabilitation, but an optimal scheme for congenital heart disease (CHD) is unknown. We piloted a system based on hemodynamic rather than anatomic factors: Function, Oxygen level, Rhythm, Complex/Coronary anatomy, and Elevated load (FORCE). Feasibility, efficacy, and safety of the FORCE tool were evaluated.Methods: Patients Results: Of 63 attempts at FORCE classification, 62 (98%) were successfully classified while one with restrictive cardiomyopathy was not. Thirty-nine (62%) were FORCE 1, 16 (25%) were FORCE 2, and 7 (11%) were FORCE 3. Almost half of FORCE 1 patients had simple or complex CHD and the majority of FORCE 2 patients had single ventricle CHD. FORCE 3 patients were more likely to have serious arrhythmias or cardiomyopathy than those in FORCE 1 or 2 (pConclusion: It was feasible to risk stratify patients with CHD using a clinical FORCE tool. The tool was effective in categorizing patients and simple to use. No adverse events occurred with fitness training over nearly 1,000 exercise training sessions. Adding diastolic dysfunction to the original model may add utility.

Background Adult survivors of Hodgkin lymphoma (HL) are at increased risk of cardiovascular (CV) events secondary to mediastinal radiation therapy (RT). Objectives In this group of patients, we assessed the association between cardiopulmonary exercise testing (CPET), as determined by percent-predicted peak Vo2 (ppVo2peak), and clinical outcomes, as well as the rate of ppVo2peak decline and sex differences. Methods All survivors of HL who were >10 years post chest RT and who underwent ≥1 CPET were enrolled from a single center. Traditional CV and treatment risk factors, along with CV events, were ascertained. Results A total of 64 patients (67% female; median age 51 years [range 26 to 70 years]) with a median follow-up time after RT of 23 years (range 11 to 41 years), and 141 CPET studies, were included. Median initial ppVo2peak was 91% (range 58% to 138%). ppVo2peak in survivors declined by 7.5 percentage points every 10-year period after RT, as compared with age- and sex-based norms (P = 0.001), even after adjusting for hypertension and history of anthracycline. Both male and female patients had a similar rate of ppVo2peak decline. However, women had a lower ppVo2peak at all times, and they developed abnormal ppVo2peak (≤85%) on average earlier than men (24.1 years vs 47.0 years after RT). Patients with abnormal ppVo2peak vs normal ppVo2peak (>85%), had an increased risk of CV events (59% vs 16%). Abnormal ppVo2peak was independently associated with the risk of CV events (adjusted HR: 6.37; 95% CI: 2.06-19.80; P = 0.001). Conclusions Percent-predicted Vo2peak in long-term survivors of HL who were treated with chest RT progressively declined as compared with population- and sex-based norms. Importantly, women developed abnormal ppVo2peak more than 2 decades earlier than male survivors. Abnormal ppVo2peak was associated with an increased risk of CV events in this group of patients., Central Illustration

Prior studies have characterized children with supraventricular tachycardia (SVT) in inpatient settings, however there is a paucity of data regarding pediatric SVT in the Emergency Department (ED) setting. We sought to describe pediatric ED visits for SVT and assess whether variability exists in care. We performed a cross-sectional study of ED visits for SVT among children

OBJECTIVE To determine the impact of provocative electrophysiology testing in postoperative congenital heart disease (CHD) patients on the management of supraventricular tachycardia (SVT) and clinical outcomes. METHODS This is a retrospective study including patients

Children and adolescents with congenital heart disease often do not have the opportunity, inclination, or education to participate in safe and effective exercise. The consequences of this behavioral pattern affect not only cardiopulmonary parameters, but also psychosocial factors, especially when lack of participation in peer activities or sports leads to isolation and further sedentary behaviors. Importantly, unlike cardiac rehabilitation programs for adults with atherosclerotic disease, the goal for congenital heart disease patients was less about "rehabilitation" and more about promotion of optimal fitness. We thus developed a comprehensive "Cardiac Fitness Program" at Boston Children's Hospital to promote exercise training, enhanced self-confidence, and motivation for patients with congenital heart disease. Since much of sustained fitness relates to consistency and behavior change, we crafted a progressive, goal-oriented exercise curriculum and augmented it with a self-learning workbook of targeted positive mindset practices to develop self-efficacy, an app for motivation and data collection, and exercise videos to demonstrate mechanics and to reiterate a positive message. We now report our experience including program structure and framework, navigating insurance, curriculum development, and outcome measures. Methods employed and barriers encountered in the initial development and execution of this program are reviewed. Key take-aways and further considerations including virtual and home-based programs are discussed.

Objectives: To describe a single institutional experience managing fetuses with supraventricular tachycardia (SVT) and to identify associations between patient characteristics and fetal and postnatal outcomes. Background: Sustained fetal SVT is associated with significant morbidity and mortality if untreated, yet the optimal management strategy remains unclear. Methods: Retrospective cohort study including fetuses diagnosed with sustained SVT (>50% of the diagnostic echocardiogram) between 1985 and 2018. Fetuses with congenital heart disease were excluded. Results: Sustained SVT was diagnosed in 65 fetuses at a median gestational age of 30 weeks (range, 14-37). Atrioventricular re-entrant tachycardia and atrial flutter were the most common diagnoses, seen in 41 and 16 cases, respectively. Moderate/severe ventricular dysfunction was present in 20 fetuses, and hydrops fetalis was present in 13. Of the 57 fetuses initiated on transplacental drug therapy, 47 received digoxin first-line, yet 39 of 57 (68%) required advanced therapy with sotalol, flecainide, or amiodarone. Rate or rhythm control was achieved in 47 of 57 treated fetuses. There were no cases of intrauterine fetal demise. Later gestational age at fetal diagnosis (odds ratio [OR], 1.1, 95% confidence interval [CI], 1.01-1.2, P = .02) and moderate/severe fetal ventricular dysfunction (OR, 6.1, 95% CI, 1.7-21.6, P = .005) were associated with postnatal SVT. Two postnatal deaths occurred. Conclusions: Fetuses with structurally normal hearts and sustained SVT can be effectively managed with transplacental drug therapy with minimal risk of intrauterine fetal demise. Treatment requires multiple antiarrhythmic agents in over half of cases. Later gestational age at fetal diagnosis and the presence of depressed fetal ventricular function, but not hydrops, predict postnatal arrhythmia burden.

Ventricular fibromas frequently present with life-threatening ventricular tachycardia (VT) or ventricular fibrillation (VF) in children. The long-term risk of sustained ventricular arrhythmias after surgical resection is unknown.The aims of this study were to quantify the VT/VF risk after surgical resection and to examine the results of early (during index surgical hospitalization) and late (≥3 months after surgery) postoperative ventricular stimulation (V-stim) studies.We performed a retrospective cohort study of all patients with ventricular fibromas who underwent surgical resection at our institution (2000-2020). The primary outcome was defined as recurrent VT/VF ≥3 months after index surgical resection.Forty-six patients with a median age at surgery of 2 years (range 0.3-18.9 years) formed our study cohort. Indications for surgery included cardiac arrest in 11 (24%), sustained VT in 16 (35%), premature ventricular contractions/nonsustained VT in 10 (22%), and hemodynamic abnormalities in 9 (20%). Of the 11 patients who presented with cardiac arrest, 4 underwent pre-resection implantable cardioverter-defibrillator (ICD) implantation, all of which were explanted at the time of surgery. An early postoperative V-stim study was performed in 26 (57%) patients, and all were negative for inducible VT/VF. Of the 13 late postoperative V-stim studies, 3 were positive: 2 underwent ICD implantation and 1 was initiated on amiodarone and underwent loop recorder implantation. At the time of last follow-up (median 1.5 years; range 0.3-16.5 years), 45 (98%) were free of clinical VT/VF and no patient with an ICD has received an appropriate shock.Surgical resection of ventricular fibromas significantly reduces the risk of life-threatening arrhythmias in children; however, a small number of patients remain vulnerable.

Objectives This study sought to evaluate for the presence of and characterize the interdigitating and entrapped myocardium within cardiac fibromas (CF) and correlate tissue findings with symptoms and surgical outcomes. Background The mechanism of ventricular tachycardia (VT) in CF is unclear. The authors hypothesized that CF harbor tongues of interdigitating myocardium, which could be a substrate for episodes of arrhythmia analogous to peri-infarct zones. Methods A total of 29 patients (14 boys) with CF were identified; all subjects had undergone at least partial tumor resection. A semiquantitative grading system was used to assess the degree of myocardial interdigitation and entrapment, myocyte morphology (hematoxylin and eosin stain and immunohistochemical stain for desmin), tumor collagen density, and cellularity (trichrome stain). The subjects’ ages at presentation, types of arrhythmia, and responses to surgery were correlated with histology. Results CF consistently demonstrated interdigitating and entrapped myocardium, and the extent correlated negatively with age at surgery, as did cellularity, whereas collagen increased with age. Median age at arrhythmia recognition was 8 months. Sustained VT was present in 18 of 29 patients (62%), and 5 of 6 patients with prenatally diagnosed conditions developed VT before 8 months. All 8 patients who experienced cardiac arrest had clinically significant arrhythmia events. Sustained arrhythmia episodes correlated with more diffuse myocyte interdigitation. Ten patients had abnormal karyotype: chromosomes 9 (n = 3) and 3 (n = 1) deletions; isolated translocations: t(4;13), t(5;11) and t(1;9); and undefined aberrations (n = 3). All patients who underwent complete resection were cured of arrhythmias, whereas 2 of 14 patients who had subtotal resections had recurrence, with resolution following re-resection in 1 patient. Conclusions Interdigitating myocardium represents a potential histopathologic substrate for VT and cardiac arrest in CF, which may also explain the occasional recurrence of arrhythmia following incomplete resection.

This study sought to determine the practical use of the recently introduced LINQ implantable loop recorder (LINQ-ILR) in a cohort of pediatric and adult congenital arrhythmia patients.Correlating symptoms to a causative arrhythmia is a key aspect of diagnosis and management in clinical electrophysiology.Retrospective review of clinical data, implantation indications, findings, and therapeutic decisions in patients who underwent LINQ-ILR implantation from April 1st, 2014 to January 30th, 2017 at Boston Children's Hospital.A total of 133 patients were included, of which 76 (57%) were male. The mean age at implantation was 15.7 ± 9.1 years with a duration of follow-up of 11.8 months. Congenital heart disease was present in 34 patients (26%), a confirmed genetic diagnosis in 50 (38%), and cardiomyopathy in 22 (26%), and the remainder were without a previous diagnosis. Syncope was the most common indication for LINQ-ILR implantation, occurring in 59 patients (44%). The median time to diagnosis was 4.5 months, occurring in 78 patients (59%). Cardiac device placement occurred in 17 patients (22%), a medication change in 9 (12%), electrophysiology study/ablation in 5 (6%), or LINQ-ILR explantation in 42 (54%). Infection or erosion occurred in 5 patients. Syncope was correlated with a diagnostic transmission (54% vs. 31%, p = 0.01).The LINQ-ILR is an important diagnostic tool, providing useful data in more than one-half of patients in 6 months. Adverse events are low. Patient selection is critical and undiagnosed syncope represents an important presenting indication for which a LINQ-ILR implant should be considered.

Background Catheter radiofrequency (RF) ablation for cardiac arrhythmias is a painful procedure. Prior work using functional near-infrared spectroscopy (fNIRS) in patients under general anesthesia has indicated that ablation results in activity in pain-related cortical regions, presumably due to inadequate blockade of afferent nociceptors originating within the cardiac system. Having an objective brain-based measure for nociception and analgesia may in the future allow for enhanced analgesic control during surgical procedures. Hence, the primary aim of this study is to demonstrate that the administration of remifentanil, an opioid widely used during surgery, can attenuate the fNIRS cortical responses to cardiac ablation. Methods and findings We investigated the effects of continuous remifentanil on cortical hemodynamics during cardiac ablation under anesthesia. In a randomized, double-blinded, placebo (PL)-controlled trial, we examined 32 pediatric patients (mean age of 15.8 years,16 females) undergoing catheter ablation for cardiac arrhythmias at the Cardiology Department of Boston Children’s Hospital from October 2016 to March 2020; 9 received 0.9% NaCl, 12 received low-dose (LD) remifentanil (0.25 mcg/kg/min), and 11 received high-dose (HD) remifentanil (0.5 mcg/kg/min). The hemodynamic changes of primary somatosensory and prefrontal cortices were recorded during surgery using a continuous wave fNIRS system. The primary outcome measures were the changes in oxyhemoglobin concentration (NadirHbO, i.e., lowest oxyhemoglobin concentration and PeakHbO, i.e., peak change and area under the curve) of medial frontopolar cortex (mFPC), lateral prefrontal cortex (lPFC) and primary somatosensory cortex (S1) to ablation in PL versus remifentanil groups. Secondary measures included the fNIRS response to an auditory control condition. The data analysis was performed on an intention-to-treat (ITT) basis. Remifentanil group (dosage subgroups combined) was compared with PL, and a post hoc analysis was performed to identify dose effects. There were no adverse events. The groups were comparable in age, sex, and number of ablations. Results comparing remifentanil versus PL show that PL group exhibit greater NadirHbO in inferior mFPC (mean difference (MD) = 1.229, 95% confidence interval [CI] = 0.334, 2.124, p < 0.001) and superior mFPC (MD = 1.206, 95% CI = 0.303, 2.109, p = 0.001) and greater PeakHbO in inferior mFPC (MD = −1.138, 95% CI = −2.062, −0.214, p = 0.002) and superior mFPC (MD = −0.999, 95% CI = −1.961, −0.036, p = 0.008) in response to ablation. S1 activation from ablation was greatest in PL, then LD, and HD groups, but failed to reach significance, whereas lPFC activation to ablation was similar in all groups. Ablation versus auditory stimuli resulted in higher PeakHbO in inferior mFPC (MD = 0.053, 95% CI = 0.004, 0.101, p = 0.004) and superior mFPC (MD = 0.052, 95% CI = 0.013, 0.091, p < 0.001) and higher NadirHbO in posterior superior S1 (Pos. SS1; MD = −0.342, 95% CI = −0.680, −0.004, p = 0.007) during ablation of all patients. Remifentanil group had smaller NadirHbO in inferior mFPC (MD = 0.098, 95% CI = 0.009, 0.130, p = 0.003) and superior mFPC (MD = 0.096, 95% CI = 0.008, 0.116, p = 0.003) and smaller PeakHbO in superior mFPC (MD = −0.092, 95% CI = −0.680, −0.004, p = 0.007) during both the stimuli. Study limitations were small sample size, motion from surgery, indirect measure of nociception, and shallow penetration depth of fNIRS only allowing access to superficial cortical layers. Conclusions We observed cortical activity related to nociception during cardiac ablation under general anesthesia with remifentanil. It highlights the potential of fNIRS to provide an objective pain measure in unconscious patients, where cortical-based measures may be more accurate than current evaluation methods. Future research may expand on this application to produce a real-time indication of pain that will aid clinicians in providing immediate and adequate pain treatment. Trial registration ClinicalTrials.gov NCT02703090

Introduction Current pediatric PACU practice administering low dose IV haloperidol for post-operative nausea and vomiting (PONV) unresponsive to other interventions for specific pediatric populations varies by anesthesia team. Identification of the problem Anecdotally, low dose haloperidol had been used safely in pediatric PACUs. Formulary recommendations for intensive monitoring were based on higher dose haloperidol used for the treatment of psychosis and the potential for QTc prolongation. QI question/Purpose of the study To clarify the magnitude of both QT prolongation and therapeutic benefit for PONV in pediatric PACU patients given low dose haloperidol. Those data would inform potential changes to the hospital formulary to differentiate guidelines for low dose IV haloperidol in the PACU from higher dose haloperidol used for psychiatric intervention. Methods An interdisciplinary QI project was developed to provide evidence to support proposed changes in the formulary. Data were collected over a six month period including pre- and post-haloperidol administration QTc and BARF scores. Descriptive statistics were used to analyze this data. Outcomes/Results During the project period, pre therapy QTc was 430±43msec (range 480-355) with heart rates of 82±16. Two patients had dosing deferred because of clinical QTc ≥ 480 (N=29). Post treatment QTc readings had an average increase of 2±22 msec, with 1 ECG exceeding the QTc cutoff of Discussion It is critical for nurses to question and evaluate practice using evidence based guidelines and quality improvement methodology. Conclusion Low dose IV haloperidol is effective at limiting PONV and has a low incidence of QT prolongation. The high monitoring environment of a pediatric PACU suggests that it can be used safely in that setting for select populations. Implications for perianesthesia nurses and future research This work resulted in developing evidence based changes to the formulary that are consistent with clinical practice. Further research is needed to determine if low-dose haloperidol can be administered safely for a younger population.

Background: Prior ECG standards in children have largely been defined without echo confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse age/sex classified group of healthy children with normal echos that included 2170 matched contemporaneous digitally acquired ECGs. We hypothesized that ECG measures and z-scores of left ventricular (LV) dimensions are correlated in healthy children. Methods: This was a secondary analysis of the previously described cohort. Six ECG measures historically associated with LV size (R V5, R V6, S V1, Q III, axis, R V6+S V1), and 13 paired echo measures were identified a-priori with LV Mass (LVMass-z) and left ventricular end diastolic volume (LVEDV-z) z-scores serving as primary echo measurement predictors. Pearson or Spearman correlations were calculated for each of the 78 ECG- echo pairs. Regression analyses were performed to assess how much variance in ECG measures was explained by variation in LV dimensions and by demographic variables (age, sex, race). Results: ECG and echo measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant in 13, (17%) or not correlated in 24 (31%). Of the 6 ECG measures of LV size, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. While many of the correlations were statistically significant, the correlations were weak (0.05-0.25). R 2 was higher for demographic variables than for echo measures in all pairs, but even with demographic variables included, the overall R 2 was < 0.17. Conclusions: In a large, diverse cohort of healthy children, there was a positive association between echo measures of LV dimension and mass and the most commonly used ECG measures of LVH. However, these correlations were weak and most of the variability in ECG measures was explained by factors other than echo derived mass or volume or measured patient demographic variables. These data question the utility of traditional ECG measurements of LV size as standalone indications for further cardiac evaluation in healthy children.

Introduction: Hypertrophic cardiomyopathy (HCM) accounts for nearly half of pediatric cardiomyopathies. While impaired exercise function has been described in adults with HCM, little is known about exercise function in children with HCM. Hypothesis: Children with HCM have impaired exercise function. Methods: A retrospective cohort study was performed. Pts Results: We identified 124 pts with 240 CPETs. The average age at time of CPET was 14.8 ± 3.0 years. Average %predicted peak VO2 (78 ± 20%) was significantly less than the population average (p 100% in 13% of tests. The %predicted peak O2 pulse (88 ± 21%; p Conclusions: Exercise function is at least moderately impaired in a substantial portion of children with HCM and this impairment tends to worsen over time. However, there is a significant subset of patient with remarkably well-preserved exercise function. Echocardiographic measurements did not correlate with exercise function in our cohort.

Background: Atrioventricular reentrant tachycardia is common in children. Catheter ablation is increasingly used as a first-line therapy with a high acute success rate, but recurrence during follow-up remains a concern. The aim of this study was to identify risk factors for recurrence after accessory pathway (AP) ablation. Methods: Retrospective cohort study including patients who underwent AP ablation between 2013 and 2018. Cox proportional hazards model was used to examine the association between patient and procedural characteristics and recurrence during follow-up. Results: From 558 AP ablation procedure, 542 (97%) were acutely successful. During a median follow-up of 0.4 (interquartile range, 0.1–1.4) years, there were 42 (8%) patients with documented recurrence. On univariate analysis, early recurrence was associated with younger age, congenital heart disease, multiple AP, AP location (right sided and posteroseptal versus left sided), cryoablation (versus radiofrequency), empirical ablation, the lack of full power radiofrequency lesions ( Conclusions: In our institutional experience, radiofrequency consolidation time

Supplemental Digital Content is available in the text., Introduction: Variability exists in the management of childhood syncope as clinicians balance resource utilization with the need to identify serious diseases. Limited evidence exists regarding the long-term impact of evidence-based guidelines (EBGs) on clinical practices. This study’s objective was to measure long-term changes in the management of syncope after implementing a syncope EBG in a single pediatric emergency department following the redistribution of resources to facilitate compliance over time. Methods: We included healthy patients aged 8–22 years, presenting to the pediatric emergency department with syncope between 2009 and 2017. Interrupted time series analysis compared testing rates and length of stay among the pre-EBG, short-term follow-up, and long-term follow-up periods. Results: The study included 1,294 subjects. From the pre-EBG period to the long-term follow-up period, recommended electrocardiogram and urine pregnancy test rose significantly [level change odds ratio (95% confidence interval) 5.56 (1.73–17.91) and 3.15 (1.07–9.32), respectively]. Testing and management not recommended by the EBG decreased significantly, including complete blood count, electrolytes, point-of-care glucose, chest radiograph, and intravenous fluids [level change odds ratio (95% confidence interval) 0.19 (0.09–0.40), 0.15 (0.07–0.32), 0.38 (0.18–0.81), 0.17 (0.06–0.49), and 0.18 (0.08–0.39), respectively]. Length of stay declined significantly. No delayed diagnoses occurred. Conclusions: Sustained improvements in syncope management persisted during long-term follow-up of the EBG despite minimal resources. The EBG was associated with increased focused evaluation and decreased low yield testing. EBGs may be useful tools to influence sustained clinical practices to promote safe, cost-effective, and high-quality care.

Prior studies have characterized children with supraventricular tachycardia (SVT) in inpatient settings, however there is a paucity of data regarding pediatric SVT in the Emergency Department (ED) setting. We sought to describe pediatric ED visits for SVT and assess whether variability exists in care. We performed a cross-sectional study of ED visits for SVT among children 18 years old from 2010 to 2017 at 33 pediatric hospitals. Visits were included if made for a primary International Disease Classification Ninth or Tenth Revision diagnosis code for SVT and intravenous (IV) adenosine was given on the initial or 2nd hospital day. We evaluated factors associated with hospital admission using multivariate logistic regression and described variability in frequency of rate of hospitalization, second-line IV antiarrhythmic medication usage, and diagnostic testing across sites. We included 2329 ED visits made by 1738 children and the median patient age was 6.3 years (IQR 1.5-11.9). There were 2 deaths (0.1% of visits). Marked variability existed between centers in rates of admission to the hospital (range 17-85%) and ICU (range 4-60%). Factors associated with admission included: younger age, male sex and presence of comorbid conditions. A second IV antiarrhythmic agent was used in 17% of visits (range 4-41% across hospitals). There was variability in rates of diagnostic testing between centers [chest x-ray (range 10-47%), complete blood count (range 10-72%), electrolytes (range 22-86%), echocardiography (range 3-68%)]. Management of SVT is variable across pediatric hospitals, suggesting an opportunity for standardization in care.

Children and adolescents with congenital heart disease often do not have the opportunity, inclination, or education to participate in safe and effective exercise. The consequences of this behavioral pattern affect not only cardiopulmonary parameters, but also psychosocial factors, especially when lack of participation in peer activities or sports leads to isolation and further sedentary behaviors. Importantly, unlike cardiac rehabilitation programs for adults with atherosclerotic disease, the goal for congenital heart disease patients was less about "rehabilitation" and more about promotion of optimal fitness. We thus developed a comprehensive "Cardiac Fitness Program" at Boston Children's Hospital to promote exercise training, enhanced self-confidence, and motivation for patients with congenital heart disease. Since much of sustained fitness relates to consistency and behavior change, we crafted a progressive, goal-oriented exercise curriculum and augmented it with a self-learning workbook of targeted positive mindset practices to develop self-efficacy, an app for motivation and data collection, and exercise videos to demonstrate mechanics and to reiterate a positive message. We now report our experience including program structure and framework, navigating insurance, curriculum development, and outcome measures. Methods employed and barriers encountered in the initial development and execution of this program are reviewed. Key take-aways and further considerations including virtual and home-based programs are discussed.

Objectives This study sought to determine the long-term effect of dual-site ventricular pacing (i.e., cardiac resynchronization therapy [CRT]) versus single-site pacing in patients with Fontan physiology and high-grade atrioventricular block (AVB). Background Chronic single-site ventricular pacing in Fontan patients is associated with significant morbidity and mortality. Methods The study conducted a retrospective review of all Fontan patients with high-grade AVB who received pacemakers at a single institution between 1990 and 2016 with follow-up of 12 months or greater. The primary study outcome was a composite of death or heart transplantation. Results Nineteen patients received CRT devices and 43 patients received single-site ventricular pacemakers (SVPMs), with a median follow-up of 4.9 years (range 1.1 to 11.3 years) and 10.4 years (range 1.1 to 26.8 years), respectively. One (5.3%) CRT patient and 11 (25.6%) SVPM patients reached the composite endpoint of death or transplant (odds ratio: 0.16; 95% confidence interval: 0.02 to 1.36; p = 0.09). Kaplan-Meier analysis showed similar rates of freedom from death or transplant between the 2 study groups over a 5-year follow-up period (p = 0.08). The proportion of SVPM patients with abnormal ventricular systolic function before device implantation (9.5%) and at follow-up (33.3%) significantly increased (p=0.009). The CRT cohort had less change in their ventricular function (42.1% before device implant, 36.8% at follow-up; p = 1.00); however, a Kaplan-Meier analysis over a 5-year follow-up period found no difference in the presence of abnormal ventricular systolic function between groups (p = 0.27). Conclusions There was no significant difference in long-term outcomes between Fontan patients who were single- or dual-site paced for high-grade AVB.

Background Left ventricular false tendons (FT) traverse the ventricular cavity and are thought to have some association with idiopathic left ventricular tachycardia (ILVT). However, reported prevalence of FT varies widely, making correlation difficult. Superior echocardiographic windows of pediatric patients may permit better analysis of FT in ILVT. Our study describes the relationship between FT and ILVT in young patients. Methods Retrospective case-control study of 30 ILVT patients with 98 controls compared for FT. Diagnosis of ILVT was made by electrocardiogram and clinical history, and for 25 patients was further confirmed by electrophysiology study (EPS). Presence of FT was identified by one blinded observer and verified by a second blinded observer. Presence of FT was then compared between ILVT patients and controls using Fisher's exact test. Results Presence of FT did not differ significantly between patients and controls (53% vs 43%, P = 0.40). Twelve FT patients (19%) had multiple FTs detected, though the incidence of ILVT was no higher in the setting of multiple FTs. A total of 25 patients with ILVT underwent EPS for intended ablation therapy, with ultimate success in 22/25 (88%) after one or more ablation sessions. Of the 25 EPS patients, FTs were present in 11, but precise correlation between successful ablation location and FT location was not possible since intraprocedural echocardiography was not performed in this patient group. Conclusions Presence of FTs did not differ between ILVT patients and controls. While FTs are not absolutely required for ILVT, they may still play a role in some cases.

Objective This study evaluates the ability of experienced pediatric electrophysiologists (EPs) to reliably classify incomplete right bundle branch block (IRBBB) and assesses its clinical utility as an isolated ECG finding in a group of healthy outpatient children without prior cardiac evaluation. Design We performed a retrospective analysis of all electrocardiographic and echocardiographic records at Boston Children's Hospital between January 1, 2005, and December 31, 2014. Echocardiographic diagnoses were identified if registered between the date of the index electrocardiogram and the ensuing year. A selected subset of 473 ECGs was subsequently reanalyzed in a blinded manner by six pediatric EPs to determine the consistency with which the finding of IRBBB could be assigned. Results Of the 331 278 ECGs registered in the BCH database, 32 127 (9.7%) met inclusion criteria and were analyzed for the prevalence of isolated right bundle conduction disturbance findings. The mean age was 12.1 ± 4.0 years, and the population was 49% male. Of the 32 127 ECGs, 72.5% were coded normal, 3.0% were coded IRBBB, and 0.5% were coded complete right bundle branch block (CRBBB). A total of 7.3% of patients coded as normal had an ensuing echocardiogram, compared to 12.5% coded IRBBB. Echo findings were recorded in 0.1% of normal and 0.2% of IRBBB. Patients with ASD-secundum type were no more likely to have isolated IRBBB on previous ECG than the general population (2.5% vs 3.0%). Analysis of inter-reader variability in ECG findings and conduction disturbance identification was high (range of IRBBB prevalence 1-20% among readers). Reinterpretation of ECGs using explicit diagnostic criteria did not demonstrate consistent discrimination of IRBBB and Normal ECGs. Conclusions IRBBB is not uncommon in a healthy school age population and is observed to have high inter-reader variability. It was associated with increased use of echocardiographic exam but was not associated with increased rate of echocardiographic findings when compared with rates for normal ECGs.

Objective To examine the association between electrocardiographic (ECG) evidence of carditis at the time of Lyme disease evaluation and a diagnosis of Lyme disease. Study design We performed an 8-center prospective cohort study of children undergoing emergency department evaluation for Lyme disease limited to those who had an ECG obtained by their treating clinicians. The study cardiologist reviewed all ECGs flagged as abnormal by the study sites to assess for ECG evidence of carditis. We defined Lyme disease as the presence of an erythema migrans lesion or a positive 2-tier Lyme disease serology. We used logistic regression to measure the association between Lyme disease and atrioventricular (AV) block or any ECG evidence of carditis. Results Of the 546 children who had an ECG obtained, 214 (39%) had Lyme disease. Overall, 42 children had ECG evidence of carditis, of whom 24 had AV block (20 first-degree). Of the patients with ECG evidence of carditis, only 21 (50%) had any cardiac symptoms. The presence of AV block (OR 4.7, 95% CI 1.8-12.1) and any ECG evidence of carditis (OR 2.3, 95% CI 1.2-4.3) were both associated with diagnosis of Lyme disease. Conclusions ECG evidence of carditis, especially AV block, was associated with a diagnosis of Lyme disease. ECG evidence of carditis can be used as a diagnostic biomarker for Lyme disease to guide initial management while awaiting Lyme disease test results.

Objective To measure the efficacy of mecasermin (recombinant human insulin‐like growth factor 1, rhIGF‐1), for treating symptoms of Rett syndrome (RTT) in a pediatric population using a double‐blind crossover study design. Methods Thirty girls with classic RTT in postregression stage were randomly assigned to placebo or rhIGF‐1 in treatment period 1 and crossed over to the opposite assignment for period 2 (both 20 weeks), separated by a 28‐week washout period. The primary endpoints were as follows: Anxiety Depression and Mood Scale (ADAMS) Social Avoidance subscale, Rett Syndrome Behaviour Questionnaire (RSBQ) Fear/Anxiety subscale, Parent Target Symptom Visual Analog Scale (PTSVAS) top three concerns, Clinical Global Impression (CGI), Parent Global Impression (PGI), and the Kerr severity scale. Cardiorespiratory‐ and electroencephalography (EEG)‐based biomarkers were also analyzed. Results There were no significant differences between randomization groups. The majority of AEs were mild to moderate, although 12 episodes of serious AEs occurred. The Kerr severity scale, ADAMS Depressed Mood subscale, Visual Analog Scale Hyperventilation, and delta average power change scores significantly increased, implying worsening of symptoms. Electroencephalography (EEG) parameters also deteriorated. A secondary analysis of subjects who were not involved in a placebo recall confirmed most of these findings. However, it also revealed improvements on a measure of stereotypic behavior and another of social communication. Interpretation As in the phase 1 trial, rhIGF‐1 was safe; however, the drug did not reveal significant improvement, and some parameters worsened.

Background Outcomes for catheter ablation of accessory pathways in pediatric patients have steadily improved, with the exception of pathways located in the anteroseptal (AS) and midseptal (MS) regions, where success is limited by the close proximity of normal atrioventricular conduction. Objective The purpose of this study was to evaluate the efficacy of different catheter approaches and ablation energy modalities used for catheter ablation at these sites. Methods A retrospective review was performed of all electrophysiology studies conducted between July 2001 and July 2017. Acute success and recurrence rates were assessed by comparing catheter approaches and energy modalities used for ablation. Results A total of 255 electrophysiology procedures were performed in 223 patients (178 AS, 72 MS, 5 unspecified). Ablation was attempted in 241 procedures, with acute success in 87% (AS 89%, MS 83%). Recurrence was evident in 18% of successful ablation procedures (AS 18%, MS 19%). Success rates were higher with repeat procedures than with primary procedures (P = .006). Multiple approaches were more often used for AS pathways, though no single approach was superior. There was no difference in success when comparing energy modalities, though the overall recurrence rate was higher for cryoablation. Significant complications occurred in 1.2% of procedures, though no patient had complete heart block. Conclusion Ablation of AS and MS pathways remains challenging. Multiple approaches are often necessary to successfully ablate AS pathways. While both ablation energy modalities were equally successful, cryoablation may be associated with a higher chance of recurrence. Recurrences and repeat procedures may be anticipated to minimize risk to normal atrioventricular conduction during ablation in these regions.

Sotalol is an important antiarrhythmic drug in the pediatric population. Given the risk of proarrhythmia, sotalol is initiated in inpatient settings, with adult studies as recent as 2015 supporting this practice.The purpose of this study was to determine the frequency of adverse events (AEs) during sotalol initiation for the management of atrial, supraventricular, or ventricular arrhythmias in pediatric patients.A retrospective cohort analysis of pediatric patients 21 years or younger initiated on oral sotalol for supraventricular tachycardia or ventricular tachycardia (VT) at Boston Children's Hospital from January 1, 2007, through July 1, 2016, was performed. The primary end point was an AE defined as significant bradycardia, new or increased ventricular arrhythmias, conduction block, or corrected QT interval (QTc) prolongation, resulting in dose reduction or cessation.There were 190 patients who met inclusion criteria, with 110 patients (58%) 6 months or younger. A total of 115 patients (60%) had congenital heart disease. Arrhythmias for which sotalol was initiated included atrioventricular reciprocating tachycardia/atrioventricular nodal reciprocating tachycardia (n = 105 [55%]), atrial flutter (n = 31 [16%]), ectopic atrial tachycardia (n = 26 [14%]), VT (n = 21 [11%]), and atrial fibrillation (n = 7 [4%]). The median pre-sotalol QTc was 438 ms (interquartile range 348-530 ms). Five patients (3%) (aged 0.1-18 years) had AEs including bradycardia40 beats/min (n = 2) and100 beats/min (n = 1) and QTc prolongation (n = 2). All 5 patients with AEs had repaired congenital heart disease.The incidence of AEs in pediatric patients initiating sotalol for atrial tachycardia, supraventricular tachycardia, or VT is low (3%), with no deaths or malignant rhythms reported in this series.

Left atrial (LA) dilation has been shown to be associated with atrial fibrillation (AF) in the adult population, with some studies indicating that larger LAs are more prone to AF recurrence. The relation of LA size to AF in the pediatric and young adult population has not been investigated. In this study, all pediatric patients (aged ≤22 years) who presented to Boston Children's Hospital from January 2002 to December 2012 with AF were reviewed. Patients with significant congenital heart disease, cardiomyopathies, proven channelopathies, previous cardiac surgery, end-stage renal disease, or severe lung disease/cystic fibrosis were excluded. LA measurements were taken using the echocardiogram performed at the initial presentation. In total, 48 patients with AF were identified. The median age at presentation was 17.1 years (range 3.7 to 22.9 years); 38 patients (79%) were men. Eleven patients (23%) had at least 1 recurrence of their AF. There was no difference in body mass index, prevalence of systemic hypertension, alcohol, stimulant, or illicit drug use between those who had an isolated episode of AF and those who had a recurrence. There was no significant difference in LA dimension Z -scores between groups, with only 2 patients (1 isolated AF, 1 recurrent AF) having Z -scores >2. In conclusion, AF in the young without underlying heart disease is not associated with LA dilation.

BACKGROUND Radiofrequency identification (RFID) detection systems are used to detect retained surgical sponges and may cause electromagnetic interference (EMI), altering intended function of cardiac pacing systems. Three pediatric patients requiring temporary pacing for postoperative atrioventricular block experienced transient inhibition of ventricular pacing during the use of RFID detection system. Bench testing was performed to evaluate the mechanism of pacemaker inhibition. METHODS Impedance of temporary pacing wires was obtained using a pacing system analyzer. Temporary pacemakers (Medtronic 5388, Medtronic 5392, and Biotronik Reocor D) at nominal settings (VVI 120 bpm, output 10 mA) were attached at the ventricular terminal to temporary pacing wires and a resistor for sham impedance in physiologic range. An RFID detection system and wand (RF Assure, model 200) or mat was tested over wires. Induced current and voltages were recorded via an oscilloscope attached to lead terminals. Inhibition of pacing was determined for the following variables: distance from wires, sham impedance, and programmed sensitivity. RESULTS In bench testing, the RFID system induced a stereotyped EMI signal in temporary pacing wires with peak root-mean-square voltage demonstrating an exponential decay relationship with increasing distance from pacing wires. Induced voltages overlapped with normal sensing range of temporary pacemakers, resulting in pacemaker inhibition at nominal settings (ventricular sensitivity 2.0 mV, distance from wand