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Heterozygous mutations of the cardiac transcription factor Nkx2-5 cause atrioventricular conduction defects in humans by unknown mechanisms. We show in KO mice that the number of cells in the cardiac conduction system is directly related to Nkx2-5 gene dosage. Null mutant embryos appear to lack the primordium of the atrioventricular node. In Nkx2-5(More)
Few data exist on the quality of life in children and adolescents with implantable cardioverter-defibrillators (ICDs). The objective of this study was to determine whether anxiety, depression, family functioning, and quality of life are related to cardiac illness severity in pediatric patients with ICDs. The subjects were 20 patients (mean age 14.8 years;(More)
OBJECTIVES We sought to study the role of I(KACh) in atrial fibrillation (AF) and the potential electrophysiologic effects of a specific I(KACh) antagonist. BACKGROUND I(KACh) mediates much of the cardiac responses to vagal stimulation. Vagal stimulation predisposes to AF, but the specific role of I(KACh) in the generation of AF and the electrophysiologic(More)
BACKGROUND The risks of sports participation for implantable cardioverter-defibrillator (ICD) patients are unknown. METHODS AND RESULTS Athletes with ICDs (age, 10-60 years) participating in organized (n=328) or high-risk (n=44) sports were recruited. Sports-related and clinical data were obtained by phone interview and medical records. Follow-up occurred(More)
BACKGROUND Characterization of reentrant circuits and targeting ablation sites remains difficult for intra-atrial reentrant tachycardias (IART) in congenital heart disease (CHD). METHODS AND RESULTS Electroanatomic mapping and entrainment pacing were performed before successful ablation of 18 IART circuits in 15 patients with CHD. Principal features of(More)
BACKGROUND Myocardial conduction depends on intercellular transfer of current at gap junctions. Atrial myocytes express three different gap junction channel proteins-connexin43 (Cx43), connexin45 (Cx45), and connexin40 (Cx40)-- whereas ventricular myocytes express only Cx43 and Cx45. However, the physiological roles of individual connexins are unknown. We(More)
We developed a technology for heart rate (HR) variability (HRV) analysis in the mouse for characterization of HR dynamics, modulated by vagal and sympathetic activity. The mouse is the principal animal model for studying biological processes. Mouse strains are now available harboring gene mutations providing fundamental insights into molecular mechanisms(More)