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

Objectives This study retrospectively assessed the safety and efficacy of permanent His bundle pacing (HBP) in patients with congenital complete heart block (CCHB). Background HBP has become an accepted form of pacing in adults. Its role in CCHB is not known. Methods Seventeen patients with CCHB who underwent successful HBP were analyzed at 6 academic centers between 2016 and 2019. Nine patients had de novo implants, and 8 patients had previous right ventricular (RV) leads. Three RV paced patients had reduced left ventricular ejection fractions at the time of HBP. Implant/follow-up device parameters, New York Heart Association functional class, QRS duration, and left ventricular ejection fraction data were analyzed. Results Patients’ mean age was 27.4 ± 11.3 years, 59% were women, and mean follow-up was 385 ± 279 days. The following parameters were found to be statistically significant between implant and follow-up, respectively: impedance, 602 ± 173 Ω versus 460 ± 80 Ω (p Conclusions HBP seems to be safe and effective, with improvement in clinical outcomes in patients with CCHB. Larger studies with longer follow-up periods are required to confirm our findings.

Permanent His-bundle pacing has been gaining popularity in the adult population requiring cardiac resynchronization therapy. Initial procedural challenges are being overcome, and this method of pacing has been shown to improve left ventricular function and heart failure symptoms secondary to ventricular dyssynchrony. Though the etiologies of ventricular dyssynchrony may differ in children and those with congenital heart disease than in adults with structurally normal hearts, His-bundle pacing may also be a preferred option in these groups to restore more physiologic electric conduction and improve ventricular function. We present a review of the current literature and suggested directions involving deploying permanent His-bundle pacing in the pediatric and congenital heart disease population.

Introduction:The SCN5A gene is implicated in many arrhythmogenic and cardiomyopathic processes. We identified a novel SCN5A variant in a family with significant segregation in individuals affected with progressive sinus and atrioventricular nodal disease, atrial arrhythmia, dilated cardiomyopathy, and early sudden cardiac arrest.Methods:A patient pedigree was created following the clinical evaluation of three affected individuals, two monozygotic twins and a paternal half-brother, which lead to the evaluation of a paternal half-sister (four siblings with the same father and three mothers) all of whom experienced varying degrees of atrial arrhythmias, conduction disease, and dilated cardiomyopathy in addition to a paternal history of unexplained death in his 50s with similar autopsy findings. The index male underwent sequencing of 58 genes associated with cardiomyopathies. Sanger sequencing was used to provide data for bases with insufficient coverage and for bases in some known regions of genomic segmental duplications. All clinically significant and novel variants were confirmed by independent Sanger sequencing.Results:All relatives tested were shown to have the same SCN5A variant of unknown significance (p. Asp197His) and the monozygotic twins shared a co-occurring NEXN (p. Glu575*). Segregation analysis demonstrates likely pathogenic trait for the SCN5A variant with an additional possible role for the NEXN variant in combination.Conclusions:There is compelling clinical evidence suggesting that the SCN5A variant p. Asp197His may be re-classified as likely pathogenic based on the segregation analysis of our family of interest. Molecular mechanism studies are pending.

Background:The initial classic Fontan utilising a direct right atrial appendage to pulmonary artery anastomosis led to numerous complications. Adults with such complications may benefit from conversion to a total cavo-pulmonary connection, the current standard palliation for children with univentricular hearts.Methods:A single institution, retrospective chart review was conducted for all Fontan conversion procedures performed from July, 1999 through January, 2017. Variables analysed included age, sex, reason for Fontan conversion, age at Fontan conversion, and early mortality or heart transplant within 1 year after Fontan conversion.Results:A total of 41 Fontan conversion patients were identified. Average age at Fontan conversion was 24.5 ± 9.2 years. Dominant left ventricular physiology was present in 37/41 (90.2%) patients. Right-sided heart failure occurred in 39/41 (95.1%) patients and right atrial dilation was present in 33/41 (80.5%) patients. The most common causes for Fontan conversion included atrial arrhythmia in 37/41 (90.2%), NYHA class II HF or greater in 31/41 (75.6%), ventricular dysfunction in 23/41 (56.1%), and cirrhosis or fibrosis in 7/41 (17.1%) patients. Median post-surgical follow-up was 6.2 ± 4.9 years. Survival rates at 30 days, 1 year, and greater than 1-year post-Fontan conversion were 95.1, 92.7, and 87.8%, respectively. Two patients underwent heart transplant: the first within 1 year of Fontan conversion for heart failure and the second at 5.3 years for liver failure.Conclusions:Fontan conversion should be considered early when atrial arrhythmias become common rather than waiting for severe heart failure to ensue, and Fontan conversion can be accomplished with an acceptable risk profile.

Purpose Many birth-assigned female/transgender male and nonbinary people (identified as masculine spectrum here) begin gender-affirming testosterone therapy by the age of 24 years. Few data inform assessment of cardiovascular health of masculine spectrum youth as a specific subgroup of the 1.5 million transgender people in the United States. The purpose of this review is to help youth-serving practitioners consider, understand, and evaluate cardiovascular health in adolescent and young adult masculine spectrum patients receiving gender-affirming testosterone treatment. Methods This is a narrative review intended to synthesize a broad body of clinical and research literature. Results Common cardiovascular health changes associated with testosterone include increased red blood cell mass and likely insignificant changes in high-density lipoprotein and low-density lipoprotein levels. Changes in heart mass, heart electrophysiology, and endothelial reactivity are likely, based on extrapolation of data from adults. Testosterone may have indirect effects on cardiovascular health through influences on depression, anxiety, stress, and anorexia nervosa as well as on behaviors such as tobacco use. Conclusions Testosterone contributes importantly to the cardiovascular health and well-being of masculine spectrum gender-diverse youth. We need to do a better job of supporting these young people with data on cardiovascular health over the life span.

This study retrospectively assessed the safety and efficacy of permanent His bundle pacing (HBP) in patients with congenital complete heart block (CCHB).HBP has become an accepted form of pacing in adults. Its role in CCHB is not known.Seventeen patients with CCHB who underwent successful HBP were analyzed at 6 academic centers between 2016 and 2019. Nine patients had de novo implants, and 8 patients had previous right ventricular (RV) leads. Three RV paced patients had reduced left ventricular ejection fractions at the time of HBP. Implant/follow-up device parameters, New York Heart Association functional class, QRS duration, and left ventricular ejection fraction data were analyzed.Patients' mean age was 27.4 ± 11.3 years, 59% were women, and mean follow-up was 385 ± 279 days. The following parameters were found to be statistically significant between implant and follow-up, respectively: impedance, 602 ± 173 Ω versus 460 ± 80 Ω (p 0.001); and New York Heart Association functional class, 1.7 ± 0.9 versus 1.1 ± 0.3 (p = 0.014). In patients with previous RV pacing, HBP resulted in a significant decrease in QRS duration: 167.1 ± 14.3 ms versus 118.3 ± 13.9 ms (p 0.0001). In de novo implants, HBP resulted in increases in QRS duration compared with baseline: 111.1 ± 19.4 ms versus 91.0 ± 4.8 ms (p = 0.016). Other parameters exhibited no statistically significant differences. During follow-up, 2 patients required lead revision due to elevated pacing thresholds.HBP seems to be safe and effective, with improvement in clinical outcomes in patients with CCHB. Larger studies with longer follow-up periods are required to confirm our findings.

Clinical genetics services continue to expand into diverse medical specialties. An ever-increasing number of non-genetics providers are independently ordering genetic tests, interpreting results, and at times, making diagnoses leading to patient care recommendations. Non-genetics healthcare providers can help increase patient access to these services, but a potential pitfall occurs when these providers either do not have adequate expertise with genetic variant interpretation or do not have access to multi-disciplinary teams including genetic counselors or clinical geneticists for advanced review. In the cardiology setting, variant misinterpretation can lead to misattribution of disease risk, unnecessary treatments or management, and potentially adverse psychosocial and financial effects. To address this, case reports and series are needed to highlight variant misinterpretation and misdiagnoses, including discussion of possible solutions and best practices for avoidance. This report details a child previously diagnosed with long QT syndrome type 4 by chromosomal microarray who was then subsequently managed for this disease by cardiac providers with insufficient expertise to critically review and question the genetic testing results. The patient was eventually referred to a pediatric electrophysiology team as part of a larger multidisciplinary cardiovascular genetics program, composed of specialist genetic counselors, cardiologists, and clinical geneticists. Advanced review and clinical evaluation raised concern about the initial genetic testing result and diagnosis. Complementary testing with a different modality to confirm or disconfirm the chromosome microarray result was performed, providing evidence that the original result reflected analytic error in the laboratory as well as interpretive error by the clinical geneticist and that the patient was misdiagnosed, and treated over the course of years, for long QT syndrome. This case shows the value of multidisciplinary teams caring for patients with inherited cardiovascular diseases.

Background Prolongation of the ECG derived QT interval predicts increased risk for sudden life-threatening arrhythmias. Many medicines are known to prolong the QT interval though current data demonstrate that progesterone given to premenopausal females 18 years old. The effects of this treatment on the corrected QT (QTc) in this population are unknown. Objective To describe the effect of exogenous progestin on the QTc in adolescent females. Methods In post-menarcheal females, Results There were 40 controls and 21 treated participants. The age range was 10 – 17 years. There were no differences between the groups with regard to race, height, weight, BMI, or blood pressure. In the controls, the mean QTc was 403 +/-19 milliseconds (ms) vs. 397 +/-15 ms in those treated (p=0.22). Those on progestin therapy had a shorter QTc by the same magnitude difference (six ms) as the hormonal naive group in the adult literature. Conclusions We report no adverse effects of progestin associated with QTc prolongation and a trend suggesting a decreased QTc in a population of post menarcheal-adolescent females.

We report the placement of a permanent transvenous nonselective His bundle pacing lead in conjunction with a transvenous pacemaker/implantable cardioverter-defibrillator in an adult with Levo-Transposition of the Great Arteries (L-TGA) and a stenotic coronary sinus (CS) ostium, which would not accommodate a transvenous left ventricular (LV) pacing lead. Nonselective His bundle pacing provided a nearly identical ventricular activation pattern in this previously unpaced patient. Many L-TGA patients will have an eventual need for permanent pacing and, given the challenges of CS cannulation, His bundle pacing may represent a preferred modality rather than pure morphologic LV pacing or surgical systemic ventricular lead placement to achieve optimal electrical synchrony.

The SCN5A gene is implicated in many arrhythmogenic and cardiomyopathic processes. We identified a novel SCN5A variant in a family with significant segregation in individuals affected with progressive sinus and atrioventricular nodal disease, atrial arrhythmia, dilated cardiomyopathy, and early sudden cardiac arrest.A patient pedigree was created following the clinical evaluation of three affected individuals, two monozygotic twins and a paternal half-brother, which lead to the evaluation of a paternal half-sister (four siblings with the same father and three mothers) all of whom experienced varying degrees of atrial arrhythmias, conduction disease, and dilated cardiomyopathy in addition to a paternal history of unexplained death in his 50s with similar autopsy findings. The index male underwent sequencing of 58 genes associated with cardiomyopathies. Sanger sequencing was used to provide data for bases with insufficient coverage and for bases in some known regions of genomic segmental duplications. All clinically significant and novel variants were confirmed by independent Sanger sequencing.All relatives tested were shown to have the same SCN5A variant of unknown significance (p. Asp197His) and the monozygotic twins shared a co-occurring NEXN (p. Glu575*). Segregation analysis demonstrates likely pathogenic trait for the SCN5A variant with an additional possible role for the NEXN variant in combination.There is compelling clinical evidence suggesting that the SCN5A variant p. Asp197His may be re-classified as likely pathogenic based on the segregation analysis of our family of interest. Molecular mechanism studies are pending.

Atrial flutter or fibrillation (AFF) remains a major chronic complication of the Fontan procedure. This complication further predisposes this patient population to thromboembolic events. However, the incidence of thromboembolic complications in Fontan patients with AFF prior to or acutely after electrical cardioversion is unknown. This study aimed to characterize the risk of post-cardioversion thromboembolic events in this population. We performed a retrospective medical record review of all patients with a history of Fontan operation treated with direct current cardioversion for AFF at Riley Children's Hospital between June 1992 and March 2014. A total of 57 patients were identified and reviewed. A total of 216 episodes of AFF required electrical cardioversion. Patients were treated with anticoagulation/antiplatelet therapy in 86.1 % (N = 186) of AFF episodes. Right atrial or Fontan conduit clots were observed in 33 patients (57.9 %) with 61 episodes of AFF. Approximately half (49.2 %, N = 30) of these episodes were treated immediately with electrical cardioversion. Twenty-five of 33 (75.8 %) patients with intracardiac thrombi had an atriopulmonary Fontan. Five (15.2 %) patients with a lateral caval tunnel had clots in the Fontan conduit, and three (9.1 %) patients with right atrium to right ventricular outflow tract (RVOT) connections presented with right atrial mural thrombi. Nine of the 57 (15.8 %) patients had documented stroke, and three (5.3 %) patients had pulmonary emboli during follow-up, although none of these emboli were associated with electrical cardioversion. The risk of thrombus and thromboembolism associated with AFF is high in the Fontan population. However, the risk of thromboembolism associated with cardioversion in the setting of anticoagulation is very low.

We report the case of a neonate born with a giant fibroma occupying the entirety of her left ventricle. Owing to the extensive resection, her postoperative course was complicated by severely diminished left ventricular function and complete heart block necessitating extracorporeal support. Ultimately, cardiac resynchronization therapy was used, after which the infant's ventricular function gradually improved and she was successfully discharged to home.

There are minimal data on the impact of genetic counselors in subspecialty clinics, including the pediatric arrhythmia clinic. This study aimed to describe the clinical encounters of a genetic counselor integrated into a pediatric arrhythmia clinic. In the 20 months between July 2015 and February 2017, a total of 1914 scheduled patients were screened for indications relevant for assessment by a genetic counselor. Of these, the genetic counselor completed 276 patient encounters, seeing 14.4% of all patients in clinic. The most expected and common indications for genetic counselor involvement were related to suspicion for primary heritable arrhythmia conditions, though patients seen in this clinic display a wide range of cardiac problems and many additional indications for genetic evaluation were identified. Roughly 75% (211/276) of encounters were for personal history of confirmed/suspected heritable disease, including cardiac channelopathies, cardiomyopathies, ventricular arrhythmias, and congenital heart defects, and 25% (65/276) were for family history of disease, including long QT syndrome and sudden unexplained death. Overall, this study shows that about 1 in 7 patients seen in a pediatric arrhythmia clinic have indications that likely benefit from genetic counselor involvement and care. Similar service delivery models embedding genetic counselors in pediatric arrhythmia clinics should be encouraged, and this model could be emulated to increase patient access to genetic counseling services.

Since its introduction, the subcutaneous implantable cardioverter-defibrillator (S-ICD) has provided the benefit of reduced mortality from ventricular tachyarrythmias without the associated short- and long-term morbidity of transvenous or epicardial implantable cardioverter-defibrillator (ICD) leads. As its name implies, the S-ICD system is implanted in its entirety, including device and lead, just under the skin beginning along the anterior axillary line, with its lead tunneled to the left parasternum and then from the xiphoid to the manubrium–sternal junction. Dislocation of the lead due to migration of the parasternal lead has been described in a minority of patients. Here, we describe an unusual case of a significant lead migration in a pediatric patient.

Objective To identify factors associated with fluoroscopy use in pediatric and congenital heart disease (CHD) patients. Design Retrospective cohort. Setting Pediatric electrophysiology lab in a single tertiary-care children's hospital. Patients Three hundred eighty-three patients who underwent electrophysiology study and ablation between January 2010 and December 2012. Methods Ablation procedures in which nonfluoroscopic navigation was employed were reviewed. Procedures using ≥10 minutes of fluoroscopy (high-fluoroscopy time; HF) were compared with those using

Rationale: Autonomic nerves from sinoatrial node (SAN) ganglia are known to regulate SAN function. However, it is unclear whether remote pulmonary vein ganglia (PVG) also modulate SAN pacemaker rhythm. Objective: To investigate whether in the mouse heart PVG modulate SAN function. Methods and Results: In hearts from 45 C57BL and 7 Connexin40+/GFP mice, we used tyrosine-hydroxylase (TH) and choline-acetyltransferase (ChAT) immunofluorescence labeling to characterize adrenergic and cholinergic elements, repectively, within the PVG and SAN. PVG project postganglionic nerves to the SAN. TH and ChAT stained nerves, enter the SAN as an extensive, dense mesh-like neural network. Neurons in PVG are biphenotypic, containing ChAT and TH positive neurons. In Langendorff-perfused hearts, we compared effects of electrical stimulation of PVG, posterior (PRCVG) and anterior right vena cava ganglia (ARCVG) using 200-2000 ms trains of pulses (300μs, 0.2-0.6mA, 200Hz). Sympathetic and/or parasympathetic blockade was achieved using 0.5μM propranolol and 1μM atropine, respectively. Epicardial optical mapping of SAN activation was performed before, during and after ganglion stimulation. PVG stimulation increased the P-P interval by 36±9%; PRCVG stimulation increased the P-P interval by 42±11%. ARCVG stimulation produced no change. Propranolol perfusion increased the PVG stimulation effect to 43±13%. Atropine caused a 5±6% decrease. In optical mapping experiments of whole hearts and isolated atrial preparations, PVG stimulation shifted the origin of SAN discharges to varying locations. Conclusions: PVG contain cholinergic, adrenergic and biphenotipic neurons whose axons project across the right atrium to richly innervate the SAN region and contribute significantly to regulation of SAN function.

Electro-anatomic mapping (EAM) has been used for more than a decade to assist in defining arrhythmia propagation for transcatheter ablation. Intra-cardiac echocardiography (ICE) has also gained acceptance as an adjunct to further define intracardiac anatomy. The integration of these two technologies (CartoSound, Biosense-Webster, Diamond Bar, CA, USA) is a recent development. In this report, we describe our early experience in the young, with and without congenital heart defects (CHD). The clinical and electrophysiologic records of the first 17 patients to undergo procedures with the CartoSound (EAM-ICE) system were reviewed. In all 17, the 3-dimensional shape of the chamber(s) of interest was created using serial tracing of ICE images. The ICE catheter was placed in the esophagus in three and through the femoral vein in 14. Descriptive analysis was performed on demographic data as well as procedural characteristics including procedure time, fluoroscopy time, geometry acquisition time, EAM duration, ablation time, procedure success, and complications. Arrhythmias comprised intra-atrial re-entry tachycardia (13 patients, 76%), Wolff-Parkinson-White syndrome (1; 6%), ventricular ectopic tachycardia (2; 12%), and atrioventricular node re-entrant tachycardia (1; 6%). Thirteen had CHD, with a median two palliative operations; six had single-ventricle anatomy. Procedure duration was 266 ± 134 min (median ± SD), and fluoroscopy time was 29 ± 28.3 min. Geometry acquisition took 41 ± 35.4 min, or 16% of the total case duration. Ablation lesions were placed in 16 cases, (cooled tip in 12) of which 15 (94%) were successful. One patient experienced mild hypotension. ICE image quality in three patients with the probe placed in the esophagus was suboptimal. Advantages of CartoSound appear to be (1) anatomy modeling in the shape imposed by the arrhythmia, (2) more accurate geometry than EAM alone, and (3) demonstration of catheter position and lesions on echo during the study. Perceived disadvantages are (1) the large sheath required for ICE (11F), and (2) significant procedure time devoted to creation of anatomy. Optimal use may be to focus on key structures required for ablation, obtaining additional views as needed.

The several forms of junctional ectopic tachycardia (JET), including the congenital form, postoperative JET, and focal junctional tachycardia are outlined. The electrophysiologic properties of this arrhythmia are described. Postoperative junctional tachycardia is address in detail, including risk factors and treatment. Congenital junctional tachycardia and focal junctional tachycardia are outlined including their treatment, with transcatheter ablation.

The diagnosis and management of cardiac arrhythmias has progressed rapidly as a science. Advances in the ability to diagnose and either suppress or eliminate arrhythmic substrates has taken an exponential trajectory. Whether utilizing three-dimensional electro-anatomic mapping systems for examining complex arrhythmias in patients with palliated congenital heart disease or genetic analysis in a search for evidence of heritable arrhythmia syndromes, technological advances have improved our ability to observe, diagnosis, and manage rhythm disturbances in patients from fetal life through adulthood. To fully harness the possibilities and continue advancements offered by these new technologies, an understanding of cardiac anatomy and cellular electrophysiology is imperative.

To identify factors associated with fluoroscopy use in pediatric and congenital heart disease (CHD) patients.Retrospective cohort.Pediatric electrophysiology lab in a single tertiary-care children's hospital.Three hundred eighty-three patients who underwent electrophysiology study and ablation between January 2010 and December 2012.Ablation procedures in which nonfluoroscopic navigation was employed were reviewed. Procedures using ≥ 10 minutes of fluoroscopy (high-fluoroscopy time; HF) were compared with those using10 minutes (low-fluoroscopy time; LF). Group comparison of characteristics was made in the entire cohort and in CHD and anatomically normal heart subsets.During the study period, 416 ablation procedures were performed involving 471 substrates in 383 patients. Median fluoroscopy time was 6.7 minutes overall and 5.1 minutes with anatomically normal hearts. LF comprised 61% of all ablation and 69% of anatomically normal hearts. LF procedures were associated with anatomically normal hearts (93% vs. 63%; P.0001). In anatomically normal hearts, HF was associated with accessory pathways (64% vs. 47%; P = .01), posteroseptal substrates (22% vs. 9%; P = .002), and ventricular substrates (12% vs. 1%; P.0001). All cases of intra-atrial reentrant tachycardia were HF. HF was associated with trans-septal puncture (47% vs. 23%; P.0001) though not when controlling for atrioventricular nodal reentrant tachycardia. LF was associated with cryoablation (56% vs. 17%; P.0001).In pediatric and congenital EP, ablation procedures using cryoablation and in patients with anatomically normal hearts are associated with LF. In accessory pathway ablation, HF was not associated with trans-septal puncture.

BACKGROUND: Children with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for sudden death, and a risk stratification tool does not exist. OBJECTIVE: The purpose of this study was to determine whether proband status, age at symptom onset, and/or sex are independent predictors of cardiac events. METHODS: A multicenter, ambispective, cohort of pediatric CPVT patients was categorized by sex, proband status, and age at symptom onset (D1: first decade of life [symptom onset