Short- and long-term outcomes in children undergoing radiofrequency catheter ablation before their second birthday

Background

Tachyarrhythmias can cause substantial morbidity and mortality in infants and very young children. Our objective was to assess early and late outcomes in children undergoing radiofrequency catheter ablation before their second birthday.

Methods

This is a retrospective review of medical records from 1995 till 2009 at a single institution with a large referral base.

Results

Thirty-four children younger than 2 years of age were brought to the electrophysiology laboratory for catheter ablation for tachyarrhythmia. Radiofrequency ablation (42 procedures) was performed in 31 children (mean weight, 7.4 kg; range, 2.6-12.3 kg). Tachyarrhythmias were atrioventricular re-entry tachycardia (19), ectopic or multifocal atrial tachycardia (6), atrial flutter (1), ventricular tachycardia (3), and congenital junctional ectopic tachycardia (2). Seventeen children presented with tachycardia-induced cardiomyopathy and heart failure. Three patients required extracorporeal life support prior to the procedure. Radiofrequency catheter ablation was successful in 74% of these very young children vs 91% in a comparison group of children older than 2 years (n = 447). Among patients with initially successful ablations, there was no tachyarrhythmia recurrence during medium- to long-term follow-up (1.4-15.0 years; mean, 7.3 years). Major complications occurred in 4 very young children. Eight of 11 patients in whom ablation failed or could not be done required another form of continued aggressive treatment.

Conclusion

Catheter ablation is indicated and successful in critically ill infants with life-threatening tachyarrhythmia refractory to medical therapy. Initially successful procedures are associated with excellent long-term outcomes, but significant complication rates require that such procedures be reserved for carefully selected patients and performed by highly skilled staff.     

Postnatal Outcome in Patients With Fetal Tachycardia

The diagnosis and management of prenatal tachyarrhythmias is well established; however, the postnatal course and outcomes are not. The purpose of our study was to review the natural history of patients with fetal tachycardia, determine the incidence of postnatal arrhythmias, and determine whether there are factors to predict which fetuses will develop postnatal arrhythmias. A retrospective chart review of patients with fetal tachyarrhythmias investigated at British Columbia Children’s and Women’s Hospitals between 1983 and 2010 was conducted. Sixty-nine mother–fetus pairs were eligible for the study. Fifty-two had fetal supraventricular tachycardia, and 17 had fetal atrial flutter. Conversion to sinus rhythm occurred prenatally in 52 % of patients. Postnatal arrhythmia occurred in two thirds of patients, with 82 % of those cases occurring within the first 48 h of life. Hydrops fetalis, female sex, and lack of conversion to sinus rhythm was predictive of postnatal arrhythmia (P = 0.01, P = 0.01, and P = 0.001, respectively). Conversion to sinus rhythm prenatally did not predict postnatal arrhythmia. Median duration of treatment was 9 months. Two postnatal deaths of unknown etiology occurred. Two thirds of all patients with prenatal tachycardia will develop postnatal arrhythmia. Prenatal factors that predict postnatal arrhythmia include hydrops, sex, and whether or not conversion to sinus rhythm occurred prenatally. The majority of patients with postnatal arrhythmia present within 48 h of life, which has clinical implications for monitoring. Postnatal outcome is generally very good with most patients being weaned off medication in 6–12 months.     

Long on QT and low on calcium

Acquired lengthening of the QT interval due to hypocalcaemia is a rare cause of arrhythmia in childhood. Early recognition, rapid institution of appropriate cardiac monitoring, and replacement therapy are essential. An endocrinal work-up may be necessary to exclude primary disorders of calcium metabolism. We report four cases documenting the varied clinical spectrum in which hypocalcaemic-induced prolongation of the QT interval and arrhythmia can occur in childhood.     

Assessment of Genetic Causes of Cardiac Arrest

Unexplained cardiac arrest is defined as a cardiac arrest in the absence of coronary artery disease and overt structural heart disease, present in 5%-10% of cardiac arrest survivors. A genetic contribution to cardiac arrest is more common in this population, most commonly attributed to an inherited ion channel abnormality leading to familial syncope and sudden death. The common causes are Long QT and Brugada syndrome, catecholaminergic ventricular tachycardia, idiopathic ventricular fibrillation, and early repolarization syndrome. Latent structural causes include inherited cardiomyopathy such as arrhythmogenic right ventricular cardiomyopathy. We review these causes in detail and a structured approach to the investigation of these patients, which provides a diagnosis in approximately half of these patients. This allows for the initiation of disease-specific treatments and enables family screening.     

Lone Atrial Fibrillation in the Pediatric Population

Background

There are few reports of pediatric studies of atrial fibrillation (AF). We sought to describe the clinical characteristics, management strategies, and recurrence rates and to identify predictors of AF recurrence in a contemporary pediatric population.

Methods

A retrospective review was performed of patients ≤ 18 years with lone AF who were seen at 4 pediatric institutions from 1996-2011. Patients with AF in the setting of thyroid disease, ventricular pre-excitation, coexisting congenital heart disease, or a history of cardiac surgery were excluded. Demographics, clinical presentation, investigations, treatment, and follow-up were analyzed.

Results

Forty-two patients were diagnosed with a first episode of lone AF, and 4 of these cases were later classified as persistent AF. Thirty-one (74%) were male patients, median age was 15.3 years, and median (interquartile range [IQR]) duration of AF episode was 12 (IQR, 7-24) hours. AF recurred in 39% (15 of 38) of patients. The Kaplan-Meier median time to estimated recurrence was 19 months. By univariate analysis, initial AF episode duration was associated with a higher risk of recurrence (hazard ratio [HR], 1.01; 95% confidence interval [CI], 1-1.02; P = 0.034). Sex, age, family history, size of the left atrium, and history of cardioversion were not associated with recurrence. Recurrence with another supraventricular tachyarrhythmia (SVT) was observed in 6 of 38 (16%) patients, and 12 patients underwent electrophysiology (EP) study, with 6 patients receiving ablation.

Conclusions

Our reported rate of recurrence of 39% is important when counseling pediatric patients and their parents on the expected course and treatment goals.     

Bovine Aortic Arch in Association with Double Inlet Left Ventricle and Pulmonary Atresia: A Novel Association

We report a newborn male who was diagnosed with a double inlet left ventricle with pulmonary atresia antenatally. Postnatally, it was difficult to determine his arch anatomy echocardiographically. Therefore, he underwent three‐dimensional computed tomography angiography, which confirmed the echocardiographic findings and demonstrated a bovine aortic arch. He additionally had a single coronary artery. To our knowledge, the association of a single ventricle with a single outlet of bovine morphology is novel.