Pediatric arrhythmias

Cellular Size, Gap Junctions, and Sodium Channel Properties Govern Developmental Changes in Cardiac Conduction

Electrical conduction in cardiac ventricular tissue is regulated via sodium (Na+) channels and gap junctions (GJs). We and others have recently shown that Na+channels preferentially localize at the site of cell-cell junctions, the intercalated disc (ID), in adult cardiac tissue, facilitating coupling via the formation of intercellular Na+nanodomains, also termed ephaptic coupling (EpC). Several properties governing EpC vary with age, including Na+channel and GJ expression and distribution and cell size. Prior work has shown that neonatal cardiomyocytes have immature IDs with Na+channels and GJs diffusively distributed throughout the sarcolemma, while adult cells have mature IDs with preferentially localized Na+channels and GJs. In this study, we perform an in silico investigation of key age-dependent properties to determine developmental regulation of cardiac conduction. Simulations predict that conduction velocity (CV) biphasically depends on cell size, depending on the strength of GJ coupling. Total cell Na+channel conductance is predictive of CV in cardiac tissue with high GJ coupling, but not correlated with CV for low GJ coupling. We find that ephaptic effects are greatest for larger cells with low GJ coupling typically associated with intermediate developmental stages. Finally, simulations illustrate how variability in cellular properties during different developmental stages can result in a range of possible CV values, with a narrow range for both neonatal and adult myocardium but a much wider range for an intermediate developmental stage. Thus, we find that developmental changes predict associated changes in cardiac conduction.

Radiofrequency catheter ablation in children with supraventricular tachycardias: intermediate term follow up results

The Purpose of the Study

Radiofrequency (RF) catheter ablation represents an important advance in the management of children with cardiac arrhythmias and has rapidly become the standard and effective line of therapy for supraventricular tachycardias (SVTs) in pediatrics. The purpose of this study was to evaluate the intermediate term follow up results of radiofrequency catheter ablation in treatment of SVT in pediatric age group.

Methods

A total of 60 pediatric patients (mean age = 12.4 ± 5.3 years, ranged from 3 years to 18 years; male: female = 37:23; mean body weight was 32.02 ± 12.3 kg, ranged from 14 kg to 60 kg) with clinically documented SVT underwent an electrophysiologic study (EPS) and RF catheter ablation at Children’s Hospital Mansoura University, Mansoura, Egypt during the period from January 2008 to December 2009 and they were followed up until October 2011.

Results

The arrhythmias included atrioventricular reentrant tachycardia (AVRT; n = 45, 75%), atrioventricular nodal reentrant tachycardia (AVNRT; n = 6, 10%), and atrial tachycardia (AT; n = 9, 15%). The success rate of the RF catheter ablation was 93.3% for AVRT, 66.7% for AVNRT, and 77.8% for AT, respectively. Procedure-related complications were infrequent (7/60, 11.7%), (atrial flutter during RF catheter ablation (4/60, 6.6%); ventricular fibrillation during RF catheter ablation (1/60, 1.6%); transient complete heart block during RF catheter ablation (2/60, 3.3%)). The recurrence rate was 8.3% (5/60) during a follow-up period of 34 ± 12 months.

Conclusion

RF catheter ablation is an effective and safe method to manage children with SVT.

Caring for the student with wolff-Parkinson-white syndrome

Wolff-Parkinson-White syndrome is a cardiac condition in which an extra electrical pathway within the heart causes an abnormal increase in heart rate. It affects one to three people of every 1,000 people worldwide, occurring more often in males. Diagnosis usually occurs during young adulthood, so it is important for school nurses to be familiar with the condition. Prophylactic treatments, as well as surgical intervention to permanently block the extra pathway, are options for people with Wolff-Parkinson-White syndrome. Tachycardia associated with Wolff-Parkinson-White syndrome can occur occasionally even when prophylactic treatment is administered. School nurses must know how to properly assess and treat episodes of tachycardia that may occur in the school setting. With proper education, school nurses can help provide a safe school environment for students with Wolff-Parkinson-White syndrome and promote successful academic achievement.

Supraventricular tachycardia in the pediatric primary care setting: Age-related presentation, diagnosis, and management

As many as 1 in 250 children experience supraventricular tachycardia (SVT), but its presentation is often vague and its symptoms mistakenly attributed to other common pediatric conditions. If SVT is correctly identified in a timely manner, most children will go on to live normal healthy lives. SVT is not covered in depth in most pediatric advanced practice nursing programs, but because of its prevalence, it should be familiar to all pediatric primary care providers. This article reviews common mechanisms of SVT and their age-related presentation, diagnosis, and management. A case study of an 8-year-old boy with SVT is presented.

[Supraventricular tachycardia in infants and children]

INTRODUCTION

Supraventricular tachycardia (SVT) is the second most frequent form of arrhythmia in pediatrics after extrasystole.

OBJECTIVES

1. To determine the clinical characteristics and treatment of SVT in infants and children. 2. To determine treatment response and the drugs used.

METHOD

A retrospective review of 61 cases of SVT requiring PICU admission (1999-2004) was performed. PICU admission was due to persistent SVT after vagal maneuvers.

RESULTS

There were 61 patients and 39 were boys (63.9%). The mean age was 2.1 years (SD +/- 3.1). Twelve patients had congenital heart disease (19.7%); three (4.9%) were admitted after heart surgery, and the remaining patients had no antecedents (60.7%). The mean cardiac frequency was 238 beats/min (SD +/- 42.86). Heart failure (HF) was observed in 14 patients (23%). Statistically significant differences were found between the presence of HF and time since onset (p < 0.01) and younger age (p < 0.01). The most frequent diagnosis was SVT due to re-entry in 28 patients (45.9%). Medical treatment was required in 46 patients (75.4%) and response was achieved in 35 (57.4%). At crisis the first drug used was adenosine triphosphate (ATP) in 35 patients (61.4%) with good response in 21 (36.8%). As maintenance therapy digoxin was used in 29 patients (50.9%) without relapses in 22 (78.6%). Radiofrequency ablation was required in 17 patients (27.9%), and there were three relapses (17.6%). The ages of patients who underwent ablation ranged from 3.5 days to 13 years.

CONCLUSIONS

1. HF was observed mainly in infants. 2. Most of the patients had good response to ATP therapy. 3. Radiofrequency ablation was mainly required in patients aged more than 1 year.

Management of the Pediatric Postoperative Cardiac Surgery Patient

Optimal management of the postoperative pediatric cardiac surgical patient requires a thorough understanding of patient anatomy, physiology, surgical repair or palliation, and clinical condition. This necessitates a dedicated team of clinicians including skilled nurses, physicians, and respiratory therapists specialized in the care of patients who have complex congenital heart disease. This article provides an overview of the multisystemic risk factors and consequences associated with cadiopulmonary bypass and cardiac surgery. An evaluation of cardiac hemodynamics and a review of major organ systems are included. Essential assessment information and interventional strategies for managing the pediatric postoperative cardiac surgery patient are detailed.