HeartHeart RateHeart DiseasesTachycardia, VentricularHeart Defects, CongenitalHeart FailureCatheter AblationElectrocardiographyVentricular Premature ComplexesAtrial FibrillationHeart BlockHeart AtriaFetal HeartAnti-Arrhythmia AgentsSyncopeElectrophysiologic Techniques, CardiacVentricular FibrillationHeart TransplantationCardiac Pacing, ArtificialDeath, Sudden, CardiacArrhythmias, CardiacDefibrillators, ImplantableHeart Septal DefectsAmiodaroneHeart Conduction SystemElectrocardiography, AmbulatoryBrugada SyndromeCardiomyopathiesBody Surface Potential MappingEchocardiographyAtrial Premature ComplexesHeart ValvesFollow-Up StudiesTreatment OutcomeBundle-Branch BlockMyocardiumAccessory Atrioventricular BundleVentricular Dysfunction, LeftAtrial FlutterStroke VolumeTime FactorsAtrioventricular BlockCardiomyopathy, DilatedFetal DiseasesRecurrenceRisk FactorsRetrospective StudiesTachycardiaElectric CountershockHeart Arrest, InducedTachycardia, SupraventricularHeart Function TestsProspective StudiesAtrial FunctionMyocardial ContractionRefractory Period, ElectrophysiologicalPredictive Value of TestsMyocardial IschemiaPacemaker, ArtificialCardiac CatheterizationSyndromeMyocytes, CardiacPericardiumRisk AssessmentLong QT SyndromeUltrasonography, PrenatalHeart VentriclesCoronary DiseaseHemodynamicsPrognosisHeart Valve DiseasesCardiac Output, LowVentricular Function, LeftPrevalenceInfant, NewbornJapanHeart, ArtificialHeart Failure, SystolicPerfusionElectrophysiologyCardiomegalyMyocardial InfarctionHeart InjuriesHeart Rate, FetalHeart SeptumCardiotonic AgentsRheumatic Heart DiseaseCase-Control StudiesMyocardial Reperfusion InjuryKaplan-Meier EstimateHeart ArrestIncidenceHeart Valve ProsthesisSurvival RateAdrenergic beta-AntagonistsHeart Failure, DiastolicAmerican Heart AssociationVentricular RemodelingDogsOxygen Consumption