TANGO2: A Rare but Important Mutation.

We report the case of a 7-year-old boy who presented with post-viral myositis, rhabdomyolysis, and hepatitis, who was later readmitted due to a seizure-like activity and ultimately found to have episodes of recalcitrant polymorphic ventricular tachycardia secondary to simultaneous QT prolongation and severe hypothyroidism. Temporary transvenous atrial pacing was successful at controlling the ventricular arrhythmias in the intensive care unit. With levothyroxine therapy and cessation of QT-prolonging medications, the corrected QT (QTc) normalized. A comprehensive arrhythmia panel identified a pathogenic mutation in KCNQ1, consistent with long QT syndrome (LQTS) type 1. After the patient experienced progressive neurodegeneration and seizures, he was referred to a genetics clinic to rule out genetic epilepsy. On the epilepsy panel of genetic testing, he was found to have two pathogenic variants in TANGO2. TANGO2 deficiency explains the initial presentation of myositis, rhabdomyolysis, hypothyroidism, and life-threatening arrhythmias surrounding a viral illness more so than the initial diagnosis of mere LQTS. However, the TANGO2 gene is not included in most comprehensive arrhythmia and cardiomyopathy panels. TANGO2 deficiency is a rare condition that often presents with arrhythmias but may be unfamiliar to many cardiologists and electrophysiologists. This case describes management strategies and caveats, which could aid in the successful diagnosis and treatment of TANGO2 deficiency at the time of presentation.

Transcatheter Leadless Pacing in Children: A PACES Collaborative Study in the Real-World Setting.

BACKGROUND: Transcatheter Leadless Pacemakers (TLP) are a safe and effective option for adults with pacing indications. These devices may be an alternative in pediatric patients and patients with congenital heart disease for whom repeated sternotomies, thoracotomies, or transvenous systems are unfavorable. However, exemption of children from clinical trials has created uncertainty over the indications, efficacy, and safety of TLP in the pediatric population. The objectives of this study are to evaluate clinical indications, procedural characteristics, electrical performance, and outcomes of TLP implantation in children. METHODS: Retrospective data were collected from patients enrolled in the Pediatric and Congenital Electrophysiology Society TLP registry involving 15 centers. Patients ≤21 years of age who underwent Micra (Medtronic Inc, Minneapolis, MN) TLP implantation and had follow-up of ≥1 week were included in the study. RESULTS: The device was successfully implanted in 62 of 63 registry patients (98%) at a mean age of 15±4.1 years and included 20 (32%) patients with congenital heart disease. The mean body weight at TLP implantation was 55±19 kg and included 8 patients ≤8 years of age and ≤30 kg in weight. TLP was implanted by femoral (n=55, 87%) and internal jugular (n=8, 12.6%) venous approaches. During a mean follow-up period of 9.5±5.3 months, there were 10 (16%) complications including one cardiac perforation/pericardial effusion, one nonocclusive femoral venous thrombus, and one retrieval and replacement of TLP due to high thresholds. There were no deaths, TLP infections, or device embolizations. Electrical parameters, including capture thresholds, R wave sensing, and pacing impedances, remained stable. CONCLUSIONS: Initial results from the Pediatric and Congenital Electrophysiology Society TLP registry demonstrated a high level of successful Micra device implants via femoral and internal venous jugular approaches with stable electrical parameters and infrequent major complications. Long-term prospective data are needed to confirm the reproducibility of these initial findings.

Pacemaker Lead Placement via Transmural Approach in an Adult With Palliated Single Ventricle Heart Disease.

Given the lack of systemic venous return to the heart, palliated single ventricle patients frequently require epicardial pacemaker implantation for management of dysrhythmias including sinus node dysfunction, atrial arrhythmias, and heart block. Repeated device hardware replacement, frequently required due to high lead thresholds or other device failure, is a challenging and significant problem for this population. 3-dimensional imaging can assist in delineating the cardiac anatomy allowing for novel approaches to intervention. We review a patient with extracardiac Fontan circulation who underwent placement of an endocardial atrial pacemaker lead via a transmural approach with a 3D-printed model used for procedural guidance.

mRNA Coronavirus Disease 2019 Vaccine-Associated Myopericarditis in Adolescents: A Survey Study.

In this survey study of institutions across the US, marked variability in evaluation, treatment, and follow-up of adolescents 12 through 18 years of age with mRNA coronavirus disease 2019 (COVID-19) vaccine-associated myopericarditis was noted. Only one adolescent with life-threatening complications was reported, with no deaths at any of the participating institutions.

Delivery of a Leadless Transcatheter Pacing System as First-line Therapy in a 28-kg Pediatric Patient Through Proximal Right Internal Jugular Surgical Cutdown.

The Micra™ transcatheter pacing system (TPS) (Medtronic, Minneapolis, MN, USA) is the only leadless pacemaker currently approved by the United States Food and Drug Administration. A limitation to the use of this device in the pediatric population is the large size of the delivery sheath. We present a 28-kg, nine-year-old male with symptomatic asystolic pauses who underwent successful placement of a Micra™ TPS via right internal jugular vein surgical cutdown as a first-line option. Current reports in the literature using the right internal jugular vein due to small patient size are limited to those involving patients with concurrent medical conditions that render the use of traditional systems unfavorable or contraindicated. Given the potential benefits of a leadless pacemaker system, its use in the pediatric population will likely continue to increase with time. This case describes technical strategies and procedural caveats that could aid in continued successful implantations of the Micra™ TPS in smaller patients as first-line therapy. In this report, room setup, the use of preprocedure vascular duplex studies, sheath manipulation, and a multidisciplinary approach are reviewed.

Torsades de Pointes During Myringotomy in a Child with Congenital Long QT Syndrome: A Case Report.

BACKGROUND Long QT syndrome (LQTS) is an arrhythmogenic heart condition that can be congenital or acquired. Prolonged ventricular repolarizations in individuals with the disorder can cause fatal arrhythmias. Abnormal functioning of cardiac ion channels leads to arrhythmias such as torsades de pointes (TdP) and may be triggered by stress or medications. Many medications used in the perioperative period are triggers for the arrythmia. CASE REPORT A 7-year-old patient with known congenital LQTS type 2 presented for bilateral myringotomy and tube placement. The patient was otherwise healthy and taking propranolol daily. Preoperative midazolam was administered for anxiolysis, and induction of anesthesia was uneventful. He sustained an episode of TdP immediately following general anesthetic induction after failure of an in situ automatic implantable cardioverter-defibrillator (AICD). External defibrillation succeeded, and the patient was stabilized in the Postanesthesia Recovery Unit before transfer to the Pediatric Intensive Care Unit. Interrogation of the AICD revealed several undelivered defibrillation attempts. A chest X-ray showed an area suggestive of an epicardial electrode fracture. The following day, the AICD was replaced with no arrythmias noted. The patient had an uneventful recovery. CONCLUSIONS In patients with a known history of LQTS, preparation and prevention are cornerstones of anesthesia care. Minimizing the use of triggering medications and emotional stress in the perioperative period, combined with ready equipment and medications to respond to arrythmias, are essential. In children, there is a greater chance of lead fracture and resulting device failure. Preoperative history of device function or interrogation of the AICD and possibly a chest X-ray are essential to ensure the integrity of the leads.

A Review of Long QT Syndrome: Everything a Hospitalist Should Know.

In this article, we will review various aspects of long QT syndrome (LQTS) necessary for hospitalists who care for children, adolescents, and young adults who have known LQTS and also review presenting features that should make one consider LQTS as a cause of hospitalization. Pediatric hospitalists care for patients who have suffered near-drowning, unexplained motor vehicular accidents, brief resolved unexpected events, sudden infant death syndrome, recurrent miscarriages, syncope, or seizures. These common conditions can be clinical clues in patients harboring 1 of 16 LQTS genetic mutations. LQTS is commonly caused by a channelopathy that can cause sudden cardiac death. Over the years, guidelines on management and recommendations for sports participation have evolved with our understanding of the disease and the burden of arrhythmias manifested in the pediatric age group. This review will include the genetic causes of LQTS, clinical features, and important historical information to obtain when these presentations are encountered. We will review medical and surgical treatments available to patients with LQTS and long-term care recommendations and prognosis for those diagnosed with LQTS.

Anomalous Origin of the Right Coronary Artery from the Pulmonary Artery in a Neonate with Turner Syndrome and Aortic Arch Hypoplasia.

Anomalous origin of the right coronary artery from the pulmonary artery, a rare congenital cardiac defect, is typically not diagnosed during infancy. On the other hand, Turner syndrome is usually diagnosed early, and it is classically associated with bicuspid aortic valve and aortic coarctation. Individuals with Turner syndrome are also at increased risk for coronary artery anomalies. We present a case of anomalous right coronary artery from the pulmonary artery in a week-old neonate who also had Turner syndrome, patent ductus arteriosus, transverse aortic arch hypoplasia, and impaired ventricular function. Prostaglandin therapy through the ductus increased the patient's myocardial perfusion. Four months after corrective surgery, she was doing well. We discuss the reperfusion phenomenon in our patient's case, as well as other considerations in this combination of congenital defects.

High burden of premature ventricular contractions in structurally normal hearts: To worry or not in pediatric patients?

BACKGROUND: There is paucity of data regarding the significance of high percentage of premature ventricular contractions (PVCs) in healthy children and their impact on left ventricular (LV) function and the risk of ventricular arrhythmias. The purpose of this study was to assess the prevalence of LV systolic dysfunction in children with frequent PVCs and determine whether PVC characteristics were predictive of LV dysfunction. METHODS: We performed a single-center retrospective review to examine the prevalence of PVC-induced cardiomyopathy and natural history of PVC burden in children with frequent PVCs. Children aged 6 months-21 years with PVCs noted on 24-hr Holter monitoring studies were enrolled. The four categories included those with a PVC burden of >10%, 10%-20%, and those with more than 20% PVC burden. RESULTS: A total of 134 children were included, 65 with more than 10% PVCs and 31 with more than 20% PVCs. Median age of the patients was 10.5 years (IQR 6.1-14.8 years), with 79 males (54.5%). Median PVC burden was 8.7% (IQR 4.2%-16.9%) with median follow-up of 2.8 years (IQR 1.2-4.6 years). During 2.8 years (1.3-4.3 years) of follow-up, the PVC burden decreased by 67% of baseline PVC burden in those who did not undergo any intervention. There were no deaths. CONCLUSION: PVCs in children with structurally normal hearts are associated with a relatively benign course, with trend toward spontaneous resolution.

Pediatric noncompaction patients with high spatial QRS-T angles are at increased risk for ventricular tachycardia.

INTRODUCTION: Noncompaction cardiomyopathy (NCCM) patients may develop sustained ventricular arrhythmias (VA). Currently no known electrocardiogram (ECG) parameter has demonstrated predictive value for VA development. The spatial QRS-T angle has demonstrated ability to identify VA in other cardiomyopathy populations. METHODS: A total of 39 patients with NCCM, defined by compact to non-compact ratio of >2.3 by magnetic resonance imaging, were assessed. The first ECG taken at time of MRI was assessed utilizing the heart rate, the QRS duration (QRSd), the corrected QT interval (QTc), and the spatial QRS-T angle (SPQRS-T angle, three-dimensional angle between the QRS and T-wave vectors) were assessed. RESULTS: Eight patients developed VA (20.5%). Median time to event was 3 months (95% CI 1.0 to 24.0 months). There were no significant differences between baseline ejection fraction or fractional shortening. Baseline median heart rate, spatial QRS-T angles, and indexed left ventricular end-diastolic volumes were all significantly higher in patients with VA development (p-value <0.05). Only heart rate and the SPQRS-T angle had significant univariate hazard ratios (HR) for VA at 1.031/beat per minute (1.001-1.071) and at a cut-off of 147 degrees the SPQRS-T angle gave a hazard ratio of HR of 5.773 (95% CI 1.161 to 28.702). The multivariate hazard ratio was only significant for the SPQRS-T angle, 1.031/degree (1.001-1.066). Survival analysis by Kaplan-Meier yielded a significant difference at a cutoff of 147 degrees. CONCLUSION: The SPQRS-T angle identified those at risk for VA development. Future studies are warranted with larger populations of noncompaction patients.

Non-invasive electrocardiographic predictors of atrial arrhythmias in patients with the Fontan palliation.

BACKGROUND: Fontan palliation patients are at risk for atrial arrhythmias post-operatively. This study aimed to evaluate whether differences in depolarization vector magnitude or spatial P-R angle can reliably predict atrial arrhythmias in patients who had undergone Fontan palliation. METHODS: A total of 115 patients who had Fontan palliation and post-Fontan catheterization were included. Atrial arrhythmias were identified in 14 patients. Measurements of ECG parameters including QRS vector magnitude, P-R duration, spatial QRS-T angle and spatial P-R angle were performed, and compared between those with and without atrial arrhythmias. RESULTS: Only the QRSvm independently differentiated those with and without atrial arrhythmias with multivariate HR of 0.743 (95% CI 0.581 to 0.951). CONCLUSION: In Fontan patients, the QRSvm was the only significant independent predictor of atrial arrhythmias.

Impact of cardiac devices on the quality of life in pediatric patients.

BACKGROUND: Cardiac rhythm devices are increasingly used in the pediatric population, although their impact on quality of life (QOL) is poorly understood. The purpose of this study was to compare (QOL) scores among pediatric device patients, healthy controls, and congenital heart disease (CHD) patients and determine the key drivers of QOL in pediatric device patients. METHODS AND RESULTS: Multicenter, cross-sectional study at 8 pediatric centers of subjects aged 8 to 18 years with either a pacemaker or defibrillator was carried out. Patient-parent pairs completed the Pediatric Quality of Life Inventory and Pediatric Cardiac Quality of Life Inventory. QOL outcomes in device patients were compared with healthy controls and patients with various forms of CHD. Structural equation modeling was used to test for differences in Pediatric Cardiac Quality of Life Inventory scores among (1) device type, (2) presence of CHD, and (3) hypothesized key drivers of QOL. One hundred seventy-three patient-parent pairs (40 defibrillators/133 pacemakers) were included. Compared with healthy controls, patients with devices and their parents reported significantly lower Pediatric Quality of Life Inventory scoring. Similarly, compared with patients with mild forms of CHD, parents and patients with devices reported significantly lower Pediatric Cardiac Quality of Life Inventory scores and were similar to patients with more severe CHD. Key drivers of patient QOL were presence of implantable cardioverter-defibrillator and CHD. For patients, self-perception was a key driver of lower QOL, whereas for parents behavioral issues were associated with lower QOL. CONCLUSIONS: Patient QOL is significantly affected by the presence of cardiac rhythm devices. Whether these effects can be mitigated through the use of psychotherapy needs to be assessed.