Congenital Long QT 3 in the Pediatric Population
Department of Pediatrics, Steven and Alexandra Cohen Children's Medical Center of New York, New Hyde Park, USA.The American journal of cardiology (Impact Factor: 3.28). 02/2012; 109(10):1459-65. DOI: 10.1016/j.amjcard.2012.01.361
There is insufficient knowledge concerning long-QT (LQT) 3 in the pediatric population to determine whether recommendations for more aggressive therapy in these patients are appropriate. An international multicenter review of 43 children with cardiac sodium channel (SCN5A) mutations and clinical manifestations of LQT syndrome without overlap of other SCN5A syndromes was undertaken to describe the clinical characteristics of LQT3 in children. Patients were aged 7.6 ± 5.9 years at presentation and were followed for 4.7 ± 3.9 years. There was significant intrasubject corrected QT interval (QTc) variability on serial electrocardiography. Forty-two percent presented with severe symptoms or arrhythmia and exhibited longer QTc intervals compared to asymptomatic patients. None of the 14 patients who underwent primary prevention implantable cardioverter-defibrillator (ICD) implantation received appropriate shocks in 41 patient-years of follow-up, while 2 of 6 patients who underwent secondary prevention ICD implantation received appropriate shocks in 30 patient-years of follow-up. Half of patients who underwent ICD implantation experienced inappropriate shocks or ICD-related complications. Mexiletine significantly shortened the QTc interval, and QTc shortening was greater in patients with longer pretreated QTc intervals. Two ICD patients with frequent appropriate ICD shocks showed immediate clinical improvement, with elimination of appropriate ICD shocks after mexiletine loading. In conclusion, severe symptoms are common in children with LQT3 and are associated with longer QTc intervals. ICD implantation is associated with significant morbidity. Mexiletine shortens the QTc interval, and it may be beneficial.
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ABSTRACT: Opinion statement: The inherited channelopathies are a rare, heterogeneous group of diseases with widely variable clinical presentations and courses. Systematic clinical and experimental work has led to identification of disease-causing genetic mutations and their biophysical manifestation. The process by which the knowledge base is developed, from genetic mutation, to cardiac myocyte, to whole heart, and finally to clinical presentation, has dramatically expanded our understanding of these diseases. Most importantly, we can now begin to comprehend how small changes at the genetic level can dramatically influence a patient's clinical course.Current Treatment Options in Cardiovascular Medicine 08/2012; 14(5):473-89. DOI:10.1007/s11936-012-0198-1
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ABSTRACT: Opinion statement: The vast majority of implantable cardioverter defibrillators (ICDs) continue to be implanted in the adult population. Accordingly, manufacturers develop devices and leads primarily for the adult population. Whilst the number of ICDs implanted in children is small in comparison, the potential benefits are large to this group. It is a common frustration among pediatric cardiologists whom implant devices that impressive technological developments continue to be developed for the adult population; as the population of children with ICDs is small, robust clinical studies often lag behind. By necessity, pediatric cardiologists and cardiothoracic surgeons have developed innovative techniques utilizing adult components in unusual configurations for children with complex congenital heart disease. As in the adult population, inappropriate shocks are one of the most limiting and concerning complications in the use of ICDs. Unfortunately, as will be discussed below, children are at increased risk of inappropriate shocks when compared with adults. The true impact of inappropriate shocks is increasingly being realized, and much of the focus in management of children with ICDs surrounds the prevention of inappropriate shocks.Current Treatment Options in Cardiovascular Medicine 08/2012; 14(5):435-42. DOI:10.1007/s11936-012-0202-9
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ABSTRACT: Objective Long QT syndrome (LQTS) is a cardiac channelopathy predisposing to syncope and sudden death secondary to LQT-triggered ventricular arrhythmias. Long QT syndrome has been regarded as a purely electrical disease. Recent reports have shown by echocardiography that LQTS patients have contraction abnormalities that are associated with cardiac arrhythmias. The purpose of this study was to determine the spectrum and prevalence of echocardiographic anomalies in a large cohort of patients diagnosed genetically and/or clinically with LQTS. Outcome MeasuresTwo-dimensional and Doppler echocardiographic studies performed during medical evaluation in Mayo's LQTS Clinic were reviewed for 216 LQTS patients. Echocardiograms were evaluated for morphologic abnormalities and atrial and ventricular size and function. Left atrial volume was indexed by body mass. Arrhythmic events were defined as a history of aborted cardiac arrest, documented ventricular tachycardia or fibrillation, and syncope. ResultsWhile 75% of patients had normal standard echocardiograms, 54 patients (25%) had at least one abnormal echocardiographic finding. Most common were subclinical cardiomyopathic changes, including increased left atrial volume index (n = 25), left or right ventricular enlargement (n = 7), and grade I-II diastolic dysfunction (n = 7). Left atrial volume index was higher in LQTS patients with arrhythmic events compared with those without (24.4 5.5mL/m(2) vs. 22.3 +/- 6.1mL/m(2), P =.02). Corrected QT intervals and left atrial volume index correlated significantly albeit weakly (r(2) = 0.04, P <.01). Concomitant congenital heart disease was found in two patients. Conclusions Subclinical cardiomyopathic changes were found in nearly 20% of LQTS patients. Left atrial enlargement was the most common finding and was associated with prolonged corrected QT and arrhythmic events. These changes may stem from underlying contraction abnormalities caused by ion channel dysfunction.Congenital Heart Disease 10/2012; 8(4). DOI:10.1111/chd.12011 · 1.08 Impact Factor
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