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.

Essentials of Paroxysmal Supraventricular Tachycardia for the Pediatrician.

Paroxysmal supraventricular tachycardia (SVT) is the most common clinical arrhythmia in young patients. With an estimated prevalence of roughly 1 in 500 children, a pediatrician may knowingly or unknowingly see several patients who are affected each year. SVT symptoms can sometimes be vague or conflated with common pediatric complaints. Different forms of SVT are predominant at different ages, sometimes complicating timely recognition and referral. Differing pathophysiology and age distribution impact risk of complications such as heart failure, or rarely, sudden death. Treatment choices continue to evolve as new medications, monitoring devices, and ablation technologies continue to mature. This review focuses on the most common types of paroxysmal SVT: atrioventricular nodal reentrant tachycardia, atrioventricular reciprocating tachycardia, and Wolff-Parkinson White syndrome. Atrial arrhythmia mechanisms are also briefly outlined. It is meant to provide practical guidelines for the diagnosis and management of patients with SVT from infancy through adolescence. [Pediatr Ann. 2021;50(3):e113-e120.].

Antiarrhythmic Treatment Duration and Tachycardia Recurrence in Infants with Supraventricular Tachycardia.

We sought to assess the effect of a shorter medication treatment course (up to 4-6 months of age) on the recurrence of infantile supraventricular tachycardia (SVT). This was a retrospective review of infants with SVT diagnosed at age 0-12 months at Rady Children's Hospital (2010-2017). Infants with structural congenital heart disease, automatic tachycardias, atrial flutter, or lack of follow-up data were excluded. Seventy-four infants met criteria. Median age at diagnosis was 6 days (IQR 0-21 days); 28.4% presented with fetal tachycardia. Median gestational age was 38.4 weeks (IQR 36-40), 30% were preterm. Median age at medication discontinuation was 6.7 months (IQR 4.6-9.8). Therapy was stopped at younger age in patients managed by pediatric electrophysiologist (vs. general pediatric cardiologist): 4.9 vs. 8.6 months (p = 0.03). Thirty-eight patients (51.4%) were treated for < 6 months; 32.4% for 6-12 months, and 16.2% for > 12 months. SVT recurrence was similar for these groups: 13.2% vs. 16.7%, and 33.3%, respectively, (p = 0.27). Most patients with recurrence required emergency care, though none had significant adverse outcomes. Infants with SVT and structurally normal cardiac anatomy, who remain recurrence free on a single agent, have no increased risk of recurrence with shorter treatment courses of 4-6 months, compared to traditional treatment duration of 6-12 months.

Transjugular liver biopsy for Fontan associated liver disease surveillance: Technique, outcomes and hemodynamic correlation.

BACKGROUND: Fontan associated liver disease (FALD) is attributed to the limitations of the Fontan circulation, resulting in congestive hepatopathy. The technique and outcomes of transjugular liver biopsies (TJLB) in Fontan patients warrant definition as part of a rigorous FALD surveillance program. METHOD: Four year review of patients with Fontan physiology who underwent a TJLB during surveillance catheterizations. Biopsy site, technique, histology, angiography, hemodynamics, and complications were reviewed to assess correlation of biopsy scores with simultaneously obtained catheterization hemodynamics. RESULTS: 125 patients with a TJLB from 10/1/14 to 5/1/18. Median age 17 years (2-50.5). Technical success 100% (125/125), all samples diagnostic. 17% (21) accessed via the left internal jugular vein, secondary to right IJ occlusion or Heterotaxy syndrome. No patients had superior compartment obstruction preventing transjugular approach. 3.2% complication rate (4/125). Complications were early in the experience, including capsular perforation (2), renal hematoma (1) and hemobilia (1), all without long-term effect and all avoidable. After standardized entry/exit angiography was adopted, no further complications noted. There is a significant correlation between the newly described modified Ishak congestive hepatic fibrosis (ICHF) score with mean Fontan pressure, time from Fontan and cardiac index. CONCLUSIONS: TJLB is an alternate method for obtaining critical FALD surveillance data, with lower complication rates that traditional techniques. Vascular anomalies in Fontan physiology appear common and warrant pre-biopsy assessment. There is a significant correlation between biopsy score, time from Fontan, mean Fontan pressure and cardiac index.

Intravenous Sotalol in the Young: Safe and Effective Treatment With Standardized Protocols.

OBJECTIVES: This study assessed the safety and efficacy of novel and standardized protocols for the use of intravenous (IV) sotalol in pediatric patients. BACKGROUND: Acute arrhythmia treatments in children remain limited. IV sotalol is a new option but pediatric experience is limited. There is no standardized protocol for rapid infusion during acute arrhythmias. This study assessed a single center's initial experience with IV sotalol in young patients, describing a protocol for rapid infusion for acute treatment, and reviewed the safety and efficacy of maintenance dosing. METHODS: This is a retrospective study of all patients who received IV sotalol at Rady Children's Hospital. Demographics, arrhythmia, hemodynamics, and effects of IV sotalol were assessed. RESULTS: Thirty-seven patients received IV sotalol from December 2015 to December 2018. Group 1 (n = 26) received sotalol for acute therapy and group 2 (n = 11) received a maintenance dose of sotalol after successful cardioversion with alternate therapies. The groups had similar demographics. Group 1 included patients with atrial flutter (n = 16), patients with supraventricular tachycardia (SVT) (n = 9), and patients with atrial ectopic tachycardia (AET) (n = 1). All 9 patients with SVT (100%) converted to sinus rhythm after failure to convert using adenosine. Median administration time was 15 min, the median dose was 30 mg/m2, and mean time to cardioversion was 14 min. Group 2 median infusion time was 120 min, the median dose was 54 mg/m2/day, and all patients maintained sinus rhythm. No patients required cessation for adverse effects previously described for IV sotalol. CONCLUSIONS: IV sotalol was safe and effective for acute and maintenance therapy in young patients. In acute patients, 30 mg/m2 over 15 min converted most patients. IV sotalol adds a valuable option to IV therapies in the young.

Rapid modification of the insect elicitor N-linolenoyl-glutamate via a lipoxygenase-mediated mechanism on Nicotiana attenuata leaves.

BACKGROUND: Some plants distinguish mechanical wounding from herbivore attack by recognizing specific constituents of larval oral secretions (OS) which are introduced into plant wounds during feeding. Fatty acid-amino acid conjugates (FACs) are major constituents of Manduca sexta OS and strong elicitors of herbivore-induced defense responses in Nicotiana attenuata plants. RESULTS: The metabolism of one of the major FACs in M. sexta OS, N-linolenoyl-glutamic acid (18:3-Glu), was analyzed on N. attenuata wounded leaf surfaces. Between 50 to 70% of the 18:3-Glu in the OS or of synthetic 18:3-Glu were metabolized within 30 seconds of application to leaf wounds. This heat-labile process did not result in free alpha-linolenic acid (18:3) and glutamate but in the biogenesis of metabolites both more and less polar than 18:3-Glu. Identification of the major modified forms of this FAC showed that they corresponded to 13-hydroxy-18:3-Glu, 13-hydroperoxy-18:3-Glu and 13-oxo-13:2-Glu. The formation of these metabolites occurred on the wounded leaf surface and it was dependent on lipoxygenase (LOX) activity; plants silenced in the expression of NaLOX2 and NaLOX3 genes showed more than 50% reduced rates of 18:3-Glu conversion and accumulated smaller amounts of the oxygenated derivatives compared to wild-type plants. Similar to 18:3-Glu, 13-oxo-13:2-Glu activated the enhanced accumulation of jasmonic acid (JA) in N. attenuata leaves whereas 13-hydroxy-18:3-Glu did not. Moreover, compared to 18:3-Glu elicitation, 13-oxo-13:2-Glu induced the differential emission of two monoterpene volatiles (beta-pinene and an unidentified monoterpene) in irlox2 plants. CONCLUSIONS: The metabolism of one of the major elicitors of herbivore-specific responses in N. attenuata plants, 18:3-Glu, results in the formation of oxidized forms of this FAC by a LOX-dependent mechanism. One of these derivatives, 13-oxo-13:2-Glu, is an active elicitor of JA biosynthesis and differential monoterpene emission.