Use of Everolimus to treat cardiac rhabdomyomas and incessant arrhythmias in a newborn: Benefits and complications.

We report treating a term neonate with tuberous sclerosis and giant rhabdomyomas who presented with incessant supraventricular tachycardia with Everolimus. The treatment was efficient in reducing tumor size and assisted as an adjunct therapy in controlling arrhythmia and limiting preexcitation. Treatment was challenged by difficulty to achieve stable drug level and limited by neutropenia as a serious side effect.

Evaluation of the fetal QT interval using non-invasive fetal ECG technology.

Non-invasive fetal electrocardiography (NI-FECG) is a promising alternative continuous fetal monitoring method that has the potential to allow morphological analysis of the FECG. However, there are a number of challenges associated with the evaluation of morphological parameters from the NI-FECG, including low signal to noise ratio of the NI-FECG and methodological challenges for getting reference annotations and evaluating the accuracy of segmentation algorithms. This work aims to validate the measurement of the fetal QT interval in term laboring women using a NI-FECG electrocardiogram monitor. Fetal electrocardiogram data were recorded from 22 laboring women at term using the NI-FECG and an invasive fetal scalp electrode simultaneously. A total of 105 one-minute epochs were selected for analysis. Three pediatric electrophysiologists independently annotated individual waveforms and averaged waveforms from each epoch. The intervals measured on the averaged cycles taken from the NI-FECG and the fetal scalp electrode showed a close agreement; the root mean square error between all corresponding averaged NI-FECG and fetal scalp electrode beats was 13.6 ms, which is lower than the lowest adult root mean square error of 16.1 ms observed in related adult QT studies. These results provide evidence that NI-FECG technology enables accurate extraction of the fetal QT interval.

Percutaneous embolization of congenital portosystemic venous fistula in an infant with down syndrome.

Congenital intrahepatic portosystemic venous shunts are rare vascular malformations often associated with severe complications. We describe a term male infant with Down syndrome with high output heart failure secondary to a congenital arterial to portal venous fistula that was diagnosed by Doppler ultrasound. Percutaneous embolizations of the left hepatic vein, portal vein, and communicating fistulas were performed without complications, resulting in clinical improvement. A subsequent hepatic ultrasound demonstrated resolution of the pathologic fistulous communication and shunting effects.

Multi-institutional study of implantable defibrillator lead performance in children and young adults: results of the Pediatric Lead Extractability and Survival Evaluation (PLEASE) study.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy in children and congenital heart disease patients is hampered by poor long-term lead survival. Lead extraction is technically difficult and carries substantial morbidity. We sought to determine the outcomes of ICD leads in pediatric and congenital heart disease patients. METHODS AND RESULTS: The Pediatric Lead Extractability and Survival Evaluation (PLEASE) is a 24-center international registry. Pediatric and congenital heart disease patients with ICD lead implantations from 2005 to 2010 were eligible. Study subjects comprised 878 ICD patients (44% congenital heart disease). Mean±SD age at implantation was 18.6±9.8 years. Of the 965 total leads, 54% were thin (≤7F), of which 57% were Fidelis, and 23% were coated with expanded polytetrafluoroethylene. There were 139 ICD lead failures (14%) in 132 patients (15%) at a mean lead age of 2.0±1.4 years, causing shocks in 53 patients (40%). Independent predictors of lead failure included younger implantation age and Fidelis leads. Actuarial analysis showed an incremental risk of lead failure with younger age at implantation: <8 years compared with >18 years (P=0.015). The actuarial yearly failure rate was 2.3% for non-Fidelis and 9.1% for Fidelis leads. Extraction was performed on 143 leads (80% thin, 7% expanded polytetrafluoroethylene coated), with lead age as the only independent predictor for advanced extraction techniques. There were 6 major extraction complications (4%) but no procedural mortality. CONCLUSIONS: This study demonstrates that ICD leads in children and congenital heart disease patients have an age-related suboptimal performance, further compounded by a high failure rate of Fidelis leads. Advanced extraction techniques were common and correlated with older lead age. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00335036.

Predictors of ECMO support in infants with tachycardia-induced cardiomyopathy.

The development of tachycardia-induced cardiomyopathy (TIC) is related to the rate and duration of supraventricular tachycardia (SVT). Infants may be more susceptible to TIC because early symptoms might be unrecognized. Extracorporeal membrane oxygenation (ECMO) may improve outcome in patients with SVT and TIC; however, clinical predictors of infants who require ECMO support have not been determined. The purpose of this study was to identify predictors of the need for ECMO in infants with SVT and TIC. Sixteen infants <6 months of age who experienced resolution of TIC following control of arrhythmia were identified. Three patients (19%) required ECMO support. Comparisons were made between patients who required ECMO and those who did not. The groups were similar with respect to age at presentation, type of SVT, rate of SVT, and degree of ventricular dysfunction. However, patients requiring ECMO had increased median M-mode-derived left ventricular end diastolic dimension (LVED) z-score when compared to the medically managed patents (+2.8 vs. 0.0, P = 0.009). No patient in the medically managed group had an LVED z-score >2.3. Infants presenting with SVT and TIC with LVED z-score >2 are at increased risk for requiring ECMO support and early use of ECMO should be considered.

Pediatric nonpost-operative junctional ectopic tachycardia medical management and interventional therapies.

OBJECTIVES: To determine the outcomes of medical management, pacing, and catheter ablation for the treatment of nonpost-operative junctional ectopic tachycardia (JET) in a pediatric population. BACKGROUND: Nonpost-operative JET is a rare tachyarrhythmia that is associated with a high rate of morbidity and mortality. Most reports of clinical outcomes were published before the routine use of amiodarone or ablation therapies. METHODS: This is an international, multicenter retrospective outcome study of pediatric patients treated for nonpost-operative JET. RESULTS: A total of 94 patients with JET and 5 patients with accelerated junctional rhythm (age 0.8 year, range fetus to 16 years) from 22 institutions were identified. JET patients presenting at age < or =6 months were more likely to have incessant JET and to have faster JET rates. Antiarrhythmic medications were utilized in a majority of JET patients (89%), and of those, amiodarone was the most commonly reported effective agent (60%). Radiofrequency ablation was conducted in 17 patients and cryoablation in 27, with comparable success rates (82% radiofrequency vs. 85% cryoablation, p = 1.0). Atrioventricular junction ablation was required in 3% and pacemaker implantation in 14%. There were 4 (4%) deaths, all in patients presenting at age < or =6 months. CONCLUSIONS: Patients with nonpost-operative JET have a wide range of clinical presentations, with younger patients demonstrating higher morbidity and mortality. With current medical, ablative, and device therapies, the majority of patients have a good clinical outcome.

Sinus bradycardia, Wolff Parkinson White, and left ventricular noncompaction: an embryologic connection?

Left ventricular noncompaction (LVNC) is an uncommon disorder that has recently been recognized as a distinct cardiomyopathy. LVNC is thought to result from an arrest in the normal process of myocardial compaction. The association of Wolff-Parkinson-White with noncompaction of the left ventricle is well recognized. Sinus bradycardia has also been associated with LVNC, although less frequently than that of Wolff-Parkinson-White. We report an infant with LVNC, Wolff-Parkinson-White, and progressive sinus bradycardia who had a myocardial vascular abnormality in the region of the sinus node evident on autopsy. We propose that the progressive nature of the conduction system abnormality was as a result of abnormal angiogenesis.

Pacemaker and defibrillator therapy in pediatrics and congenital heart disease.

Pacemakers and defibrillators have a growing use in pediatrics and in patients with congenital heart disease, but they present unique problems and implications for their implantation and follow-up. Congenital and surgically acquired rhythm disturbances are common, but the efficacy of device therapy is not well established in these patient groups. The diversity and complexity of pediatric patients and congenital heart disease make device management a highly individualized art. There are technical issues related to device implantation that have necessitated novel approaches to using leads and device that were not designed with children specifically in mind. The current guidelines and indications for implantable device therapy for children and congenital heart disease are reviewed, as well as some of the specific limitations and problems encountered.

Advances in the approach to treatment of supraventricular tachycardia in the pediatric population.

Supraventricular tachycardia is relatively common in children. Although most forms are not life threatening, treatment options depend on appropriate diagnosis. In certain patients, medical treatments are adequate for controlling symptoms. For those in whom medical therapy is inadequate or undesirable, invasive electrophysiology techniques are a viable treatment option. Increasing experience with radiofrequency catheter ablation techniques has led to improved success rates and decreased complication rates. New technologies, such as nonradiographic mapping systems and novel ablation catheters, are additional tools that can improve the ability of pediatric electrophysiologists to approach treating tachycardia mechanisms that have previously been too challenging to treat safely.

Implantable cardioverter defibrillators in children.

The use of implantable cardioverter defibrillators in children presents several unique challenges for the pediatric cardiologist. Size considerations and hardware limitations are important in the current generation of devices that are not designed with children in mind. Defibrillator devices are used to prolong life, which may have significant implications for leads and electrodes that are affixed to the heart in a child who has continued growth potential. A greater number of children with congenital heart defects are surviving into adulthood, many of whom have a risk of late sudden death following repair. These patients may also have unique anatomic considerations that may affect device placement. This article will address some of the issues faced when considering the use of implantable-defibrillator therapy in the pediatric population.

Polymorphic ventricular tachycardia and KCNJ2 mutations.

We sought to identify the electrophysiologic basis of life-threatening events associated with polymorphic ventricular tachycardia (PVT) in young patients with heterozygous KCNJ2 mutations. PVT describes a beat-to-beat alternating QRS axis and morphology during ventricular tachycardia. PVT may be well tolerated and even asymptomatic in young patients without other heart disease, but an association with syncope, cardiac arrest, or sudden death has long been known. Little is known of the basis of life-threatening events associated with PVT in this setting. We identified heterozygous KCNJ2 mutations (R67W and C101R respectively) in 2 adolescents with PVT (cycle length > 375 ms, < 160 beats/minute). Biophysical properties of wild-type and mutant KCNJ2 channels were characterized during heterologous expression in Xenopus oocytes. Despite a large tachycardia burden, neither patient experienced symptoms during electrocardiographic documentation of PVT. One patient had a history of cardiac arrest, but neither had other evidence of heart disease. Both patients were treated with an implantable cardioverter-defibrillator (ICD). In one patient, ICD interrogation identified rapid ventricular tachycardia (cycle length of 190 to 270 ms), terminated with a single 29-J asynchronous shock, as the cause of 2 syncopal episodes occurring 19 months apart. Biophysical characterization of KCNJ2-C101R demonstrated a loss-of-function and a dominant-negative effect on Kir2.1. Similar effects were previously observed for KCNJ2-R67W. Heterozygous mutations in KCNJ2 can cause life-threatening ventricular arrhythmias. Arrhythmia documented during cardiac arrest is rapid ventricular tachycardia; ICD is effective therapy for cardiac arrest in patients with PVT due to KCNJ2 mutation.