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.

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.

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.