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Congenital complete heart block (CCHB) affects 1 in 20,000 newborns. This study evaluates fetal and neonatal risk factors predictive of neonatal pacemaker placement in antibody-mediated complete heart block. The Children’s Hospital Los Angeles institutional fetal, pacemaker, and medical record databases were queried for confirmed SSA/SSB cases of CCHB between January 2004 and July 2019. Cases excluded were those with a diagnosis beyond the neonatal period, diagnosis of a channelopathy, or if maternal antibody status was unknown. We recorded the gestational age (GA), birth weight (BW), fetal heart rates (FHRs) of the last echocardiogram before delivery, specific neonatal ECG and echocardiogram findings, age at pacemaker placement, and mortality. Of 43 neonates identified with CCHB, 27 had confirmed maternal antibody exposure. Variables associated with neonatal pacemaker implantation were FHRs

Our institution established a Fontan surveillance plan, which included ambulatory rhythm monitoring (ARM) at 6, 10, 13, 16 and 19 years old, for early detection of Fontan-associated complications. We conducted a retrospective chart review of Fontan patients followed at our institution 2014–2018 to determine the utility of surveillance ARMs. 139 ARMs from 83 patients were included. ARMs with supraventricular tachycardia, sinus node dysfunction, accelerated junctional rhythm, > 1st degree atrioventricular block, and complex ventricular ectopy were classified as positive for arrhythmia. Arrhythmias were occult if detected on surveillance ARM. The ARM indication was surveillance in 78 (56%) and clinically indicated in 61 (44%). 52 (37%) ARMs in 27 (33%) patients had an arrhythmia. There was no difference in the age of patients with and without arrhythmias [median 10.9 (6.5, 17.1 years) vs. 8.8 (7, 13.6 years), p = 0.5]. Clinically indicated ARMs more frequently demonstrated arrhythmias than surveillance ARMs (52% vs. 26%, p

Although ectopic atrial tachycardia (EAT) is common following surgery for congenital heart disease (CHD), there are limited data regarding this arrhythmia. This study assessed risk factors and outcomes for patients less than one year of age with post-operative EAT. This was a retrospective analysis of infants undergoing CHD surgery from 2007 to 2020. Patients and surgeries with EAT were compared to controls without EAT. Out of 5372 infant CHD surgeries, EAT developed in 129 (2.5%). Compared to controls, the EAT cohort was younger (median 7 vs 85 days, p 0.01), weighed less at time of surgery (3.3 vs 4.2 kg, p 0.01), and was more likely to have DiGeorge syndrome (7.7% vs 3.0%, p 0.01). Multivariate analysis revealed total anomalous venous connection (TAPVC) repair (odds ratio [OR] 2.8; 95% confidence interval 1.5-5.2), DiGeorge syndrome (OR 2.4; 1.1-5.2), Society of Thoracic Surgeons-European Association for Cardio-Thoracic surgery (STAT) category ≥ 4 (OR 2.1; 1.0-4.4), and longer cardiopulmonary bypass times (OR 1.1; 1.0-1.2) as independent risk factors for EAT. The onset of EAT occurred a median of 9 days (IQR 5-14 days) after CHD surgery. Antiarrhythmic treatment was initiated in 109/129 patients (84%) with propranolol (71%) and amiodarone (24%) the most commonly used medications. Although 15 (11.6%) patients did not survive to hospital discharge, EAT was not directly implicated in any deaths. EAT occurred after 2.5% of infant CHD surgeries. In addition to TAPVC repair, longer and more complex surgeries were associated with an increased the risk for the development of post-operative EAT.

There is minimal data regarding antegrade-only accessory pathways in young patients. Given evolving recommendations and treatments, retrospective analysis of the clinical and electrophysiologic properties of antegrade-only pathways in patients

We present the course and management of an adolescent male with hypertrophic cardiomyopathy. The importance of family history, early screening, accurate evaluation of hypertrophy, and risk stratification for eligibility for a defibrillator in hypertrophic cardiomyopathy are emphasized. Learning points are seen in the light of new guidelines. (Level of Difficulty: Intermediate.), Graphical abstract

Few medical devices are designed and marketed specifically for children. Instead, adult devices are often repurposed and used off-label in pediatrics. The innovation gap between pediatric and adult devices is complex and multifactorial. This review aims to summarize the medical device landscape, describe barriers to pediatric device development, and provide an update on current strategies to help overcome these limitations. Medical devices are regulated by the Food and Drug Administration. They are registered, cleared, or approved on the basis of a 3-tier risk classification system and a differentiated set of regulatory pathways. This includes some for products that receive special designations on the basis of specific aspects that warrant more rapid review and approval. Pediatric devices number only one-quarter of those developed for adults for multiple reasons. Clinically, innovators must adjust their products to address the smaller sizes, growth, and longer duration of use in children. Smaller sample sizes and population heterogeneity also challenge the ability to obtain sufficient safety data for regulatory submissions. Financial concerns stem from lower pediatric reimbursement rates coupled with a lack of nationally standardized coverage. There are a number of promising initiatives, including the Pediatric Device Consortia Program, Early Feasibility Studies, and the new System of Hospitals for Innovation in Pediatrics – Medical Devices. However, the gap will likely not be narrowed without broad cooperation across stakeholders from industry, academia, patient advocacy groups, health care providers, investors, payors, regulators, and Congress.

Congenital complete heart block (CCHB) affects 1 in 20,000 newborns. This study evaluates fetal and neonatal risk factors predictive of neonatal pacemaker placement in antibody-mediated complete heart block. The Children's Hospital Los Angeles institutional fetal, pacemaker, and medical record databases were queried for confirmed SSA/SSB cases of CCHB between January 2004 and July 2019. Cases excluded were those with a diagnosis beyond the neonatal period, diagnosis of a channelopathy, or if maternal antibody status was unknown. We recorded the gestational age (GA), birth weight (BW), fetal heart rates (FHRs) of the last echocardiogram before delivery, specific neonatal ECG and echocardiogram findings, age at pacemaker placement, and mortality. Of 43 neonates identified with CCHB, 27 had confirmed maternal antibody exposure. Variables associated with neonatal pacemaker implantation were FHRs 50 bpm (p = 0.005), neonatal heart rates 52 bpm (p = 0.015), and neonatal left ventricular fractional shortening (FS) percentages 34% (p = 0.03). On multivariate analysis, FHR remained significant (p = 0.03) and demonstrated an increased risk of neonatal pacemaker placement by an odds ratio of 12.5 (95% CI 1.3-116, p = 0.05). The median GA at which the FHR was obtained was 34 weeks (IQR 26-35 weeks). Neonatal pacemaker placement was highly associated with a FHR 50 bpm, neonatal HR 52 bpm, and neonatal FS 34%. FHRs at 34 weeks GA (IQR 26-35 weeks) correlated well with postnatal heart rates and were predictive of neonatal pacemaker placement.

Our institution established a Fontan surveillance plan, which included ambulatory rhythm monitoring (ARM) at 6, 10, 13, 16 and 19 years old, for early detection of Fontan-associated complications. We conducted a retrospective chart review of Fontan patients followed at our institution 2014-2018 to determine the utility of surveillance ARMs. 139 ARMs from 83 patients were included. ARMs with supraventricular tachycardia, sinus node dysfunction, accelerated junctional rhythm, 1st degree atrioventricular block, and complex ventricular ectopy were classified as positive for arrhythmia. Arrhythmias were occult if detected on surveillance ARM. The ARM indication was surveillance in 78 (56%) and clinically indicated in 61 (44%). 52 (37%) ARMs in 27 (33%) patients had an arrhythmia. There was no difference in the age of patients with and without arrhythmias [median 10.9 (6.5, 17.1 years) vs. 8.8 (7, 13.6 years), p = 0.5]. Clinically indicated ARMs more frequently demonstrated arrhythmias than surveillance ARMs (52% vs. 26%, p 0.01). Compared to patients without arrhythmias, those with arrhythmias were more likely to be female (48% vs. 23%, p = 0.02), have a single right ventricle (46% vs. 19%, p 0.01) and longer QRS duration on ECG [100 (91, 116 ms) vs. 94 (84, 104 ms), p = 0.046]. Patients with occult arrhythmias were less likely to have moderate to severe atrioventricular valvar regurgitation (0% vs. 46%; p = 0.04) or ventricular dysfunction (0% vs. 46%; p = 0.04) than those with clinical arrhythmia(s). Arrhythmia findings resulted in change in management for 16/52 (31%) ARMs. The findings suggest the frequent presence of arrhythmias on periodic ARMs in patients following the Fontan procedure regardless of symptomatic status.

The publisher regrets that in the original published version of this article, one of the author’s name was incorrectly presented as “Yaniv Bar Cohen”. The correct presentation should have been “Yaniv Bar-Cohen” and is now presented correctly in this article.

UNSTRUCTURED Pediatric medical devices cover a broad array of indications and risk profiles, and have helped to reduce disease burden and improve quality of life for numerous children. However, many of the devices used in pediatrics are not intended for or tested on children. Several barriers have been identified that pose difficulties in bringing pediatric medical devices to the market. These include a small market and small sample size; unique design considerations; regulatory complexities; lack of infrastructure for research, development, and evaluation; and low return on investment. In 2007, the Food and Drug Administration (FDA) created the Pediatric Device Consortia (PDC) Grants Program under the administration of the Office of Orphan Products Development. In 2018, the FDA awarded over US $30 million to five new PDCs. The West Coast Consortium for Technology & Innovation in Pediatrics (CTIP) is one of these PDCs and is centered at the Children’s Hospital Los Angeles. In February 2019, CTIP convened its primary stakeholders to discuss its priorities and activities for the new grant cycle. In this paper, we have presented a report of the summit proceedings to raise awareness and advocate for patients and pediatric medical device innovators as well as to inform the activities and priorities of other organizations and agencies engaged in pediatric medical device development.

Congenital central hypoventilation syndrome (CCHS) patients are at risk for life-threatening cardiac arrhythmias, and presentation is dependent on their PHOX2B gene mutation. We describe the presentation of life-threatening arrhythmias in our cohort of CCHS patients. We reviewed the records of 72 CCHS patients seen at CHLA from 2004 to 2018. Data collected included demographics, PHOX2B genotype, ventilatory support, clinical symptoms, ambulatory cardiac monitoring results, and presence of cardiac pacemaker. Sixteen of 72 patients had evidence of potential life-threatening cardiac arrhythmias. PHOX2B genotypes were 20/25 polyalanine repeat expansion mutation (PARM), 20/26 PARM, 20/27 PARM, 20/32 PARM, and c.245C T non-polyalanine repeat mutation. 11/16 patients were ventilated during sleep only. Symptoms included syncope, dizziness, chest pain, tingling in the left arm, and palpitations. 15/16 patients had recorded ambulatory cardiac monitoring. 5/16 patients were symptomatic without significant sinus pauses. 12/16 patients had implantation of cardiac pacemakers. 9/12 had significant sinus pauses on ambulatory monitoring, and 7/12 patients were symptomatic.Conclusion: CCHS patients have potential life-threatening arrhythmias requiring cardiac pacemaker implantation. Many of these patients are symptomatic with significant sinus pauses on ambulatory monitoring. However, some symptomatic patients with no significant pauses on ambulatory monitoring may still require cardiac pacemaker implantation.What is Known:• CCHS patients are at risk for life-threatening sinus pauses and require cardiac pacemaker implantation.What is New:• CCHS patients regardless of PHOX2B genotype are at risk for significant sinus pauses. Many CCHS patients with significant sinus pause on ambulatory cardiac monitoring are symptomatic and most present with syncope. Some symptomatic patients do not have significant sinus pauses but may still require cardiac pacemaker implantation.

Background Echocardiography is important in the follow-up of children with permanent pacemakers due to the risk for cardiomyopathy. However, the value of standard measurements is unclear in the setting of expected dyssynchrony caused by ventricular pacing. Objectives The study sought to assess and compare echocardiographic parameters of ventricular function in children with chronic ventricular pacing. Methods Echocardiographic studies of patients with normal cardiac anatomy and ventricular pacing for heart block were retrospectively evaluated for routine measurements of systolic and diastolic ventricular function. Results In 60 echocardiograms that were analyzed, fractional shortening (FS) had moderate correlation with ejection fraction (EF; R = 0.64, p Conclusions FS and EF are moderately correlated to each other and may both be appropriate in the evaluation of systolic function in chronically paced children. TDI values may be misleading, measuring low diastolic function despite normal LA area.

We have developed a rechargeable fetal micropacemaker in order to treat severe fetal bradycardia with comorbid hydrops fetalis. The necessarily small form factor of the device, small patient population, and fetal anatomy put unique constraints on the design of the recharging system. To overcome these constraints, a custom high power field generator was built and the recharging process was controlled by utilizing pacing rate as a measure of battery state, a feature of the relaxation oscillator used to generate stimuli. The design and in vitro and in vivo verification of the recharging system is presented here, showing successful generation of recharging current in a fetal lamb model.

AIMS: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an ion channelopathy characterized by ventricular arrhythmia during exertion or stress. Mutations in RYR2-coded Ryanodine Receptor-2 (RyR2) and CASQ2-coded Calsequestrin-2 (CASQ2) genes underlie CPVT1 and CPVT2, respectively. However, prognostic markers are scarce. We sought to better characterize the phenotypic and genotypic spectrum of CPVT, and utilize molecular modelling to help account for clinical phenotypes. METHODS AND RESULTS: This is a Pediatric and Congenital Electrophysiology Society multicentre, retrospective cohort study of CPVT patients diagnosed at

Implantation and maintenance of a permanent cardiac pacing system in children remains challenging due to small patient size, congenital heart defects and somatic growth. We are developing a novel epicardial micropacemaker for children that can be implanted on the epicardium within the pericardial space via a minimally-invasive technique. The key design configurations include a novel open-coiled lead in which living tissue replaces the usual polymeric support for the coiled conductor. To better understand and be able to predict the behavior of the implanted lead, we performed a radiographic image-based modeling study on a chronic animal test. We report a pilot study in which two mechanical dummy pacemakers with epicardial leads were implanted into an adult pig model via a minimally invasive approach. Fluoroscopy was obtained on the animal on Post-Operative Days #9, #35 and #56 (necropsy). We then constructed an analytic model to estimate the in vivo stress conditions on the open-coil lead based on the analysis of orthogonal biplane radiographic images. We obtained geometric deformation data of the implanted lead including elongation magnitudes and bending radii from sequenced films of cardiac motion cycles. The lead stress distribution was investigated on each film frame and the point of maximum stress (Mean Stress = 531.4 MPa; Alternating Stress = ± 216.4 MPa) was consistently where one of the leads exited the pericardial space, a deployment that we expected to be unfavorable. These results suggest the modeling approach can provide a basis for further design optimization. More animal tests and modeling will be needed to validate whether the novel lead design could meet the requirements to withstand ~200 million cardiac motion cycles over 5 years.

Congenital complete heart block (CCHB) is a life-threatening medical condition in the unborn fetus with insufficiently validated prenatal interventions. Maternal administration of medications aimed at decreasing the immune response in the fetus and beta-agonists intended to increase fetal cardiac output have shown only marginal benefits. Anti-inflammatory therapies cannot reverse CCHB, but may decrease myocarditis and improve heart function. Advances in prenatal diagnosis and use of strict surveillance protocols for delivery timing have demonstrated small improvements in morbidity and mortality. Ambulatory surveillance programs and wearable fetal heart rate monitors may afford early identification of evolving fetal heart block allowing for emergent treatment. There is also preliminary data suggesting a roll for prevention of CCHB with hydroxychloroquine, but the efficacy and safety is still being studied. To date, intrauterine fetal pacing has not been successful due to the high-risk invasive placement techniques and potential problems with lead dislodgement. The development of a fully implantable micropacemaker via a minimally invasive approach has the potential to pace fetal patients with CCHB and thus delay delivery and allow fetal hydrops to resolve. The challenge remains to establish accepted prenatal interventions capable of successfully managing CCHB in utero until postnatal pacemaker placement is successfully achieved.

We have developed a rechargeable fetal micropacemaker in order to treat severe fetal bradycardia with comorbid hydrops fetalis, a life-threatening condition in pre-term non-viable fetuses for which there are no effective treatment options. The small size and minimally invasive form factor of our design limit the volume available for circuitry and a power source. The device employs a fixed-rate and fixed-amplitude relaxation oscillator and a tiny, rechargeable lithium ion power cell. For both research and clinical applications, it is valuable to monitor the electrode-myocardium interface in order to determine that adequate pacemaker output is being provided. This is typically accomplished by observing the minimal stimulus strength that achieves threshold for pacing capture. The output of our simple micropacemaker cannot be programmatically altered to determine this minimal capture threshold, but a safety factor can be inferred by determining the refractory period for ventricular capture at a given stimulus strength. This is done by measuring the minimal timing between naturally occurring QRS complexes and pacing stimuli that successfully generate a premature ventricular contraction. The method was tested in a pilot study in four fetal sheep and the data demonstrate that a relative measure of threshold is obtainable. This method provides valuable real-time information about the electrode-tissue interface.

Dominic Abrams, MD, Sam Asirvatham, MD, Yaniv Bar-Cohen, MD, FAAP, FACC, FHRS, Andrew D. Blaufox, MD, FHRS, FACC, Bryan Cannon, MD, FHRS, John Clark, MD, Macdonald Dick, MD, FHRS, FACC, Anne Freter, MSN, FHRS, Naomi J. Kertesz, MD, FACC, FHRS, Joel A. Kirsh, MD, FRCP(C), FHRS, CEPS, John Kugler, MD, FAAC, FAAP, FAHA, Martin LaPage, MD, MS, FAAP, FHRS, CCDS, CEPS, Francis X. McGowan, MD, FAAP, Christina Y. Miyake, MD, Aruna Nathan, MBBS, FRCA, John Papagiannis, MD, FHRS, CEPS, Thomas Paul, MD, FHRS, FACC, Andreas Pflaumer, MD, FRACP, FCSANZ, CEPS, Allan C. Skanes, MD, FRCPC, William G. Stevenson, MD, FAHA, FHRS, FACC, Nicholas Von Bergen, Frank Zimmerman, MD, FAHA, FHRS

This paper discusses the technical and safety requirements for cardiac pacing of a human fetus with heart failure and hydrops fetalis secondary to complete heart block. Engineering strategies to meet specific technical requirements were integrated into a systematic design and implementation consisting of a novel fetal micropacemaker, a percutaneous implantation system, and a sterile package that enables device storage and recharging maintenance in a clinical setting. We further analyzed observed problems on myocardial fixation and pacing lead fatigue previously reported in earlier preclinical trials. This paper describes the technical refinements of the implantable fetal micropacemaker to overcome these challenges. The mechanical performance has been extensively tested to verify the improvement of reliability and safety margins of the implantation system.

Pediatric medical devices cover a broad array of indications and risk profiles, and have helped to reduce disease burden and improve quality of life for numerous children. However, many of the devices used in pediatrics are not intended for or tested on children. Several barriers have been identified that pose difficulties in bringing pediatric medical devices to the market. These include a small market and small sample size; unique design considerations; regulatory complexities; lack of infrastructure for research, development, and evaluation; and low return on investment. In 2007, the Food and Drug Administration (FDA) created the Pediatric Device Consortia (PDC) Grants Program under the administration of the Office of Orphan Products Development. In 2018, the FDA awarded over US $30 million to five new PDCs. The West Coast Consortium for Technology & Innovation in Pediatrics (CTIP) is one of these PDCs and is centered at the Children’s Hospital Los Angeles. In February 2019, CTIP convened its primary stakeholders to discuss its priorities and activities for the new grant cycle. In this paper, we have presented a report of the summit proceedings to raise awareness and advocate for patients and pediatric medical device innovators as well as to inform the activities and priorities of other organizations and agencies engaged in pediatric medical device development.

Background: Permanent cardiac pacemakers require invasive procedures with complications often related to long pacemaker leads. We are developing a percutaneous pacemaker for implantation of an entire pacing system into the pericardial space. Methods: Percutaneous micropacemaker implantations were performed in 6 pigs (27.4–34.1 kg) using subxyphoid access to the pericardial space. Modifications in the implantation methods and hardware were made after each experiment as the insertion method was optimized. In the first 5 animals, nonfunctional pacemaker devices were studied. In the final animal, a functional pacemaker was implanted. Results: Successful placement of the entire nonfunctional pacing system into the pericardial space was demonstrated in 2 of the first 5 animals, and successful implantation and capture was achieved using a functional system in the last animal. A sheath was developed that allows retractable features to secure positioning within the pericardial space. In addition, a miniaturized camera with fiberoptic illumination allowed visualization of the implantation site before electrode insertion into myocardium. All animals studied during follow-up survived without symptoms after the initial postoperative period. Conclusions: A novel micropacemaker system allows cardiac pacing without entering the vascular space or surgical exposure of the heart. This pericardial pacemaker system may be an option for a large number of patients currently requiring transvenous pacemakers but is particularly relevant for patients with restricted vascular access, young children, or those with congenital heart disease who require epicardial access.

Background Supraventricular tachycardia (SVT) in children can be difficult to treat when first-line therapies (beta-blockade or digoxin) are not effective. Both flecainide and amiodarone are used as second-line therapies. We sought to compare the efficacy and safety of flecainide and amiodarone in pediatric patients with recurrent SVT. Methods Pediatric patients treated with oral flecainide or oral amiodarone for SVT between 2006 and 2015 were studied. Tachycardia mechanisms included orthodromic reciprocating tachycardia (ORT), intra-atrial reentrant tachycardia (IART), and ectopic atrial tachycardia (EAT). Outcomes were classified as full success, partial success (requiring additional intervention), or failure. Results Seventy-four patients were included (median age 46 days, range 1 day to 19 years). Flecainide was used in 47 patients and amiodarone in 27 patients. Full success was achieved in 68% and 59%, respectively (P = 0.28). Partial success was achieved in 13% and 19%, respectively (P = 0.12). Treatment failed in 19% and 22%, respectively (P = 0.97). Ten crossover patients received the second medication after the first failed. Of five amiodarone-to-flecainide crossovers, four achieved success on flecainide alone. Of five flecainide-to-amiodarone crossovers, two achieved success. Minor adverse events occurred in 9% of flecainide and 22% of amiodarone patients (P = 0.16). No significant differences were seen by arrhythmia subtype (36 EAT, 28 ORT, 10 IART), congenital heart disease (n = 38), or age group (56 infants). Conclusions Oral flecainide and amiodarone achieved meaningful arrhythmia control in 81% and 78% of pediatric patients with recurrent SVT, respectively. Those who failed amiodarone had encouraging outcomes when changed to flecainide.

Background Atrioventricular nodal reentrant tachycardia (AVNRT) typically occurs in adolescents and adults with limited data regarding AVNRT in young children. Methods All patients with AVNRT who underwent electrophysiology study and ablation between 2005 and 2012 were retrospectively studied. Patients were stratified by age

Although guidelines for routine follow-up of pacemakers and implantable cardioverter defibrillators (ICDs) are available for adults, minimal data supports their appropriateness in pediatrics and congenital heart disease. This study aimed to define current practices of cardiac rhythm device (CRD) follow-up among pediatric electrophysiologists. Pediatric and Congenital EP Society (PACES) members were surveyed regarding frequency of CRD in-person follow-up as well as transtelephonic monitoring (TTM) and remote monitoring (RM) practices. If home monitoring was used, the effect on in-person follow-up was also evaluated. A total of 106 PACES members responded to the survey. Uncomplicated pacemaker and ICD patients were both followed in-person at a median interval of 6 months (range 1-12 months). TTM was utilized by 67 % of responders (median interval 3 months; range 1-6 months), while RM was used by 87 % for pacemakers (median interval 3 months; range 1-6 months) and 92 % for ICDs (median interval 3 months; range 2 weeks-6 months). When TTM was used, 21 % of responders reduced their frequency of pacemaker clinic visits. In comparison, RM reduced the frequency of clinic visits for pacemakers and ICDs in 32 and 31 % of responders, respectively. Patient age was an independent factor in determining CRD follow-up for 49 % of responders. While CRD follow-up by pediatric electrophysiologists in general follows adult guidelines, individual practices widely vary. In contrast to published recommendations in adults, TTM and RM utilization does not reduce the frequency of in-person visits for the majority of pediatric electrophysiologists.

Cardiac resynchronization therapy (CRT) has proven to be a powerful and effective tool in the treatment of adults with severe dilated or ischemic cardiomyopathy. A substantial portion of the adult heart failure population has severely depressed systolic function, heart failure symptoms, QRS prolongation, and left bundle branch block. Indications for CRT in adults are commonly focused on these characteristics. However, pediatric patients represent a heterogeneous group with many etiologies of heart failure and anatomic variants, with most of them not fitting the typical adult CRT criteria. The heterogeneity of the pediatric population has hindered the identification of ideal candidates for CRT, but initial experience with CRT in various groups of pediatric patients has been encouraging. This article reviews indications for and outcomes of CRT in pediatric and congenital heart disease patients.

In general, the prognosis is poor for pediatric patients who experience out-of-hospital (OOH) cardiac arrest, with survival rates of 12% to 29%.The purpose of this study was to describe the causes and outcomes of pediatric patients with documented ventricular fibrillation (VF) at resuscitation from OOH cardiac arrest with sustained return of spontaneous circulation after defibrillation and survival to hospital admission.Retrospective analysis of OOH-VF patients19 years of age evaluated between 2004 and 2016 was performed. Primary outcome measures included demographics, arrest and resuscitation parameters, cardiac diagnoses, survival, and neurologic outcome.Forty-five patients fulfilled study criteria (median age 12 years; range 2 months to 18 years). Cardiac arrest occurred in public in 68% of cases, with bystander cardiopulmonary resuscitation in 42% before arrival of emergency medical services. All patients underwent defibrillation (1-6 shocks) with return of spontaneous circulation and survival to hospital admission. Underlying etiologies were primary electrical disease (33%), cardiomyopathy (27%), congenital heart disease (11%), other (13%), and unknown (16%). Before arrest, 40% of patients had a cardiac diagnosis and 26% had symptoms. Ultimately, 40 of 45 patients (89%) survived resuscitation to hospital discharge. During 72 ± 37 months of follow-up, 38% of survivors had a normal neurologic outcome, whereas 32% had mild neurologic impairment and 30% had moderate-to-severe neurologic impairment.In pediatric patients resuscitated from OOH-VF, a cardiovascular cause was identified in80%. Regardless of cause, survival and neurologic prognosis appear improved compared to patients with asystole or pulseless electrical activity. These findings support early rhythm assessment and advanced cardiopulmonary resuscitation protocols in pediatric cardiac arrest victims.

A 2-week-old infant with normal intracardiac anatomy presented to the emergency department in a hypertensive crisis with acute cardiac failure. Despite extensive evaluation, no underlying disease was found. The patient’s hypertension and cardiac dysfunction resolved after 1 week of supportive care in the PICU, and she was discharged within 2 weeks of presentation. The patient’s history revealed transplacental exposure to the α-adrenergic agonist methyldopa for 10 weeks before delivery. Her age at presentation and the self-limited nature of cardiac sequelae with complete resolution of cardiac dysfunction suggest withdrawal effects from this exposure. Whereas the rebound hypertensive effects of α-adrenergic agonists are well established in the adult population, this report shows an unusual adverse outcome of in utero exposure to methyldopa.

Background— Although retrograde decremental accessory pathways (DAPs) are thought to typically present as permanent junctional reciprocating tachycardia (permanent junctional reciprocating tachycardia), they may also be diagnosed unexpectedly during electrophysiology study. We aimed to compare the clinical and electrophysiological characteristics of patients with DAPs to an age-matched cohort with nondecremental accessory pathways. Methods and Results— We retrospectively studied pediatric patients (30 ms. Twenty-six patients with DAPs were compared with 73 controls (mean age at electrophysiology study 9.8±5.7 and 10.3±5.2 years, respectively [ P =nonsignificant]). Compared with controls, patients with DAPs had more frequent syncope (5/26 [19%] versus 3/73 [4%]; P =0.02) and ventricular dysfunction (6/26 [23%] versus 4/73 [6%]; P =0.04). Only 11 (42%) DAP patients manifested clinical permanent junctional reciprocating tachycardia, and these patients had more syncope (5/11 [45%] versus 0/15 [0%]; P P =0.001), and longer ventriculo-atrial times (mean maximum ventriculo-atrial times of 283±116 ms versus 208±42 ms; P =0.02) compared with those with DAPs without clinical permanent junctional reciprocating tachycardia. DAPs and controls had similar rates of acute ablation success (23/26 [89%] versus 67/73 [92%]; P =nonsignificant) and recurrences (1/23 [4%] versus 2/67 [3%]; P =nonsignificant). Conclusions— The majority of pediatric patients with DAPs do not present with clinical permanent junctional reciprocating tachycardia. DAPs are associated with more severe symptoms, but ablation outcomes are similar to those of age-matched controls.

Author(s): Roston, Thomas M; Haji-Ghassemi, Omid; LaPage, Martin J; Batra, Anjan S; Bar-Cohen, Yaniv; Anderson, Chris; Lau, Yung R; Maginot, Kathleen; Gebauer, Roman A; Etheridge, Susan P; Potts, James E; Van Petegem, Filip; Sanatani, Shubhayan | Abstract: BackgroundCatecholaminergic polymorphic ventricular tachycardia (CPVT) is often a life-threatening arrhythmia disorder with variable penetrance and expressivity. Little is known about the incidence or outcomes of CPVT patients with ≥2 variants.MethodsThe phenotypes, genotypes and outcomes of patients in the Pediatric and Congenital Electrophysiology Society CPVT Registry with ≥2 variants in genes linked to CPVT were ascertained. The American College of Medical Genetics a Genomics (ACMG) criteria and structural mapping were used to predict the pathogenicity of variants (3D model of pig RyR2 in open-state).ResultsAmong 237 CPVT subjects, 193 (81%) had genetic testing. Fifteen patients (8%) with a median age of 9 years (IQR 5-12) had ≥2 variants. Sudden cardiac arrest occurred in 11 children (73%), although none died during a median follow-up of 4.3 years (IQR 2.5-6.1). Thirteen patients (80%) had at least two RYR2 variants, while the remaining two patients had RYR2 variants plus variants in other CPVT-linked genes. Among all variants identified, re-classification of the commercial laboratory interpretation using ACMG criteria led to the upgrade from variant of unknown significance (VUS) to pathogenic/likely pathogenic (P/LP) for 5 variants, and downgrade from P/LP to VUS for 6 variants. For RYR2 variants, 3D mapping using the RyR2 model suggested that 2 VUS by ACMG criteria were P/LP, while 2 variants were downgraded to likely benign.ConclusionsThis severely affected cohort demonstrates that a minority of CPVT cases are related to ≥2 variants, which may have implications on family-based genetic counselling. While multi-variant CPVT patients were at high-risk for sudden cardiac arrest, there are insufficient data to conclude that this genetic phenomenon has prognostic implications at present. Further research is needed to determine the significance and generalizability of this observation. This study also shows that a rigorous approach to variant re-classification using the ACMG criteria and 3D mapping is important in reaching an accurate diagnosis, especially in the multi-variant population.

A Report from the Training and Credentialing Committee of the Pediatric and CongenitalElectrophysiology SocietyEndorsed by the Heart Rhythm SocietyCOMMITTEE MEMBERSEdward P. Walsh, MD, FHRS, ChairYaniv Bar-Cohen, MDAnjan S. Batra, MD, FHRS*Macdonald Dick II, MD, FHRSChristopher Erickson, MDFrank Fish, MDRobert M. Hamilton, MD

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.

The study objective was to determine the predictors of new-onset arrhythmia among infants with single-ventricle anomalies during the post-Norwood hospitalization and the association of those arrhythmias with postoperative outcomes (ventilator time and length of stay) and interstage mortality.After excluding patients with preoperative arrhythmias, we used data from the Pediatric Heart Network Single Ventricle Reconstruction Trial to identify risk factors for tachyarrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia, junctional ectopic tachycardia, and ventricular tachycardia) and atrioventricular block (second or third degree) among 544 eligible patients. We then determined the association of arrhythmia with outcomes during the post-Norwood hospitalization and interstage period, adjusting for identified risk factors and previously published factors.Tachyarrhythmias were noted in 20% of subjects, and atrioventricular block was noted in 4% of subjects. Potentially significant risk factors for tachyarrhythmia included the presence of modified Blalock-Taussig shunt (P = .08) and age at Norwood (P = .07, with risk decreasing each day at age 8-20 days); the only significant risk factor for atrioventricular block was undergoing a concomitant procedure at the time of the Norwood (P = .001), with the greatest risk being in those undergoing a tricuspid valve procedure. Both tachyarrhythmias and atrioventricular block were associated with longer ventilation time and length of stay (P .001 for all analyses). Tachyarrhythmias were not associated with interstage mortality; atrioventricular block was associated with mortality among those without a pacemaker in the unadjusted analysis (hazard ratio, 2.3; P = .02), but not after adding covariates.Tachyarrhythmias are common after the Norwood procedure, but atrioventricular block may portend a greater risk for interstage mortality.