Transesophageal pacing studies reduce readmission but prolong initial admission in infants with supraventricular tachycardia: A cost-comparison analysis.

Background: Supraventricular tachycardia (SVT) is a common arrhythmia. Infants with SVT are often admitted to initiate antiarrhythmics. Transesophageal pacing (TEP) studies can be used to guide therapy prior to discharge.

Familial Recurrence Patterns in Congenitally Corrected Transposition of the Great Arteries: An International Study.

Background: Congenitally corrected transposition of the great arteries (ccTGA) is a rare disease of unknown cause. We aimed to better understand familial recurrence patterns.

Methods: An international, multicentre, retrospective cohort study was conducted in 29 tertiary hospitals in 6 countries between 1990 and 2018, entailing investigation of 1043 unrelated ccTGA probands.

Sudden cardiac death in children and young adults without structural heart disease: a comprehensive review.

Sudden cardiac death (SCD) is a rare clinical encounter in pediatrics, but its social impact is immense because of its unpredicted and catastrophic nature in previously healthy individuals. Unlike in adults where the primary cause of SCD is related to ischemic heart disease, the etiology is diverse in young SCD victims. Although certain structural heart diseases may be identified during autopsy in some SCD victims, autopsy-negative SCD is more common in pediatrics, which warrants the diagnosis of sudden arrhythmic death syndrome (SADS) based upon the assumption that the usual heart rhythm is abruptly replaced by lethal ventricular arrhythmia.

Molecular characterization of the calcium release channel deficiency syndrome.

We identified a potentially novel homozygous duplication involving the promoter region and exons 1-4 of the gene encoding type 2 cardiac ryanodine receptor (RYR2) that is responsible for highly penetrant, exertion-related sudden deaths/cardiac arrests in the Amish community without an overt phenotype to suggest RYR2-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT). Homozygous RYR2 duplication (RYR2-DUP) induced pluripotent stem cell cardiomyocytes (iPSC-CMs) were generated from 2 unrelated patients. There was no difference in baseline Ca2+ handling measurements between WT-iPSC-CM and RYR2-DUP-iPSC-CM lines.

Identification of a Novel Homozygous Multi-Exon Duplication in RYR2 Among Children With Exertion-Related Unexplained Sudden Deaths in the Amish Community.

Importance: The exome molecular autopsy may elucidate a pathogenic substrate for sudden unexplained death.

Objective: To investigate the underlying cause of multiple sudden deaths in young individuals and sudden cardiac arrests that occurred in 2 large Amish families.

Design, Setting, And Participants: Two large extended Amish families with multiple sudden deaths in young individuals and sudden cardiac arrests were included in the study.

Significance of automated external defibrillator in identifying lethal ventricular arrhythmias.

Automated electrical defibrillator (AED) is critical in saving children who develop unexpected cardiac arrest (CA), but its diagnostic capacity is not fully acknowledged. Retrospective cohort study of patients with aborted sudden cardiac death (SCD) was performed. Twenty-five patients (14 males) aged 1.

Clinical Outcomes and Modes of Death in Timothy Syndrome: A Multicenter International Study of a Rare Disorder.

Objectives: The objective of this study was to evaluate contemporary clinical outcomes and identify triggers for arrhythmias or sudden death in an international cohort of Timothy Syndrome (TS) patients including those with novel TS-associated CACNA1C mutations.

Background: TS is an extremely rare genetic disorder of the L-type cardiac channel Ca1.2 encoded by CACNA1C.

Impact of Pharmacist Intervention on Electrocardiogram Monitoring of Pediatric Patients on Multiple QTc Interval-Prolonging Medications.

Objectives: To determine whether dedicated pharmacy services improve the rate of electrocardiogram (ECG) monitoring in patients at risk for medication-induced QTc interval prolongation. In addition, determine how pediatric institutions currently monitor patients at risk for medication-induced QTc interval prolongation.

Methods: A pharmacist-driven monitoring protocol to detect medication-induced QTc interval prolongation was developed using published literature.

Transient Ischemic Attack and Ischemic Stroke in Danon Disease with Formation of Left Ventricular Apical Thrombus despite Normal Systolic Function.

Danon disease is a rare X-linked dominant skeletal and cardiac muscle disorder presenting with hypertrophic cardiomyopathy, Wolf-Parkinson-White syndrome, skeletal myopathy, and mild intellectual disability. Early morbidity and mortality due to heart failure or sudden death are known in Danon disease, more in males than in females. Here, we present a 17-year-old female adolescent with Danon disease and severe concentric hypertrophy with normal left ventricular (LV) systolic function, who has been complaining of intermittent headache and weakness for about 3 years, initially diagnosed with hemiplegic migraine.

The clinical and genetic spectrum of catecholaminergic polymorphic ventricular tachycardia: findings from an international multicentre registry.

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.

Development and impact of arrhythmias after the Norwood procedure: A report from the Pediatric Heart Network.

Objectives: 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.

Methods: 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.

Catecholaminergic polymorphic ventricular tachycardia in children: analysis of therapeutic strategies and outcomes from an international multicenter registry.

Background: Catecholaminergic polymorphic ventricular tachycardia is an uncommon, potentially lethal, ion channelopathy. Standard therapies have high failure rates and little is known about treatment in children. Newer options such as flecainide and left cardiac sympathetic denervation are not well validated.

Predicting utility of exercise tests based on history/holter in patients with premature ventricular contractions.

Premature ventricular contractions (PVCs) are considered benign in patients with structurally normal hearts, particularly if they suppress with exercise. Catecholaminergic polymorphic ventricular tachycardia (CPVT) requires exercise testing to unmask the malignant phenotype. We studied risk factors and Holter monitor variables to help predict the necessity of exercise testing in patients with PVCs.

Cone reconstruction and ventricular septal defect closure for neonatal Ebstein's anomaly.

Neonatal presentation of Ebstein's anomaly is associated with significant morbidity and mortality. We illustrate the technical aspects of the cone procedure and the closure of a ventricular septal defect, to achieve biventricular repair in a neonate. This includes the assessment of the leaftlet apparatus, detachment, division of chordae, annular plication, leaflet rotation and reinsertion in the neoannulus.

Resynchronization therapy in pediatric and congenital heart disease patients: an international multicenter study.

Objectives: Our objective was to evaluate the short-term safety and efficacy of cardiac resynchronization therapy (CRT) in children.

Background: Cardiac resynchronization therapy has been beneficial for adult patients with poor left ventricular function and intraventricular conduction delay. The efficacy of this therapy in the young and in those with congenital heart disease (CHD) has not yet been established.

Atrial fibrillation in KCNE1-null mice.

Although atrial fibrillation is the most common serious cardiac arrhythmia, the fundamental molecular pathways remain undefined. Mutations in KCNQ1, one component of a sympathetically activated cardiac potassium channel complex, cause familial atrial fibrillation, although the mechanisms in vivo are unknown. We show here that mice with deletion of the KCNQ1 protein partner KCNE1 have spontaneous episodes of atrial fibrillation despite normal atrial size and structure.

Radiofrequency ablation of a left-sided atrioventricular pathway in a patient with Marfan syndrome.

Supraventricular tachycardia is a documented feature of Marfan syndrome. The safety and efficacy of radiofrequency ablation in this population of patients, however, has not been reported. We report on the successful use of radiofrequency ablation utilizing a trans-septal approach for the treatment of supraventricular tachycardia produced by an accessory muscular atrioventricular connection in a patient with Marfan syndrome.

Calmodulin kinase II and arrhythmias in a mouse model of cardiac hypertrophy.

Background: Calmodulin kinase (CaMK) II is linked to arrhythmia mechanisms in cellular models where repolarization is prolonged. CaMKII upregulation and prolonged repolarization are general features of cardiomyopathy, but the role of CaMKII in arrhythmias in cardiomyopathy is unknown.

Methods And Results: We studied a mouse model of cardiac hypertrophy attributable to transgenic (TG) overexpression of a constitutively active form of CaMKIV that also has increased endogenous CaMKII activity.

Calmodulin inhibitor W-7 unmasks a novel electrocardiographic parameter that predicts initiation of torsade de pointes.

Background: We have shown that the calmodulin inhibitor W-7 suppresses torsade de pointes (TdP) without shortening the QT interval, which is consistent with other findings that QT prolongation, per se, is insufficient to generate TdP. ECGs were analyzed from a well-characterized animal model of TdP to identify more reliable predictors of this life-threatening ventricular arrhythmia.

Methods And Results: TdP was induced using methoxamine and clofilium in 12 of 14 rabbits pretreated with vehicle control, whereas pretreatment with W-7 (50 micromol/kg), an inhibitor of the intracellular Ca2+-binding protein calmodulin, significantly suppressed TdP induction (1 of 11 rabbits with TdP, P<0.