Arrhythmias, CardiacHeartHeart RateHeart Defects, CongenitalFetal HeartCardiac ElectrophysiologyElectrocardiography, AmbulatoryElectrocardiographyVentricular FibrillationVentricular Premature ComplexesTachycardia, VentricularAnti-Arrhythmia AgentsExercise TestMyocardiumTachycardia, SupraventricularDeath, Sudden, CardiacArrhythmia, SinusAtrial FibrillationHeart Conduction SystemHeart VentriclesAction PotentialsHeart FailureTime FactorsHeart DiseasesHeart TransplantationHeart AtriaTachycardiaHeart BlockCardiac Complexes, PrematureLong QT SyndromeMyocytes, CardiacMyocardial IschemiaCardiac Pacing, ArtificialHeart ValvesDefibrillators, ImplantableElectrophysiologic Techniques, CardiacDogsMyocardial ContractionCatheter AblationMyocardial InfarctionAtrial FlutterVentricular DysfunctionMyocardial Reperfusion InjuryModels, CardiovascularCardiomyopathiesHeart Function TestsAmiodaroneHemodynamicsFlecainideElectric CountershockNAV1.5 Voltage-Gated Sodium ChannelFollow-Up StudiesTorsades de PointesCoronary DiseaseCardiomyopathy, DilatedEchocardiographyRisk FactorsAdrenergic beta-AntagonistsHeart Arrest, InducedVentricular Function, LeftDigitalis GlycosidesHeart ArrestTreatment OutcomeAutonomic Nervous SystemPerfusionDeath, SuddenCardiotonic AgentsStroke VolumeProspective StudiesDisease Models, AnimalTelemetryVentricular Dysfunction, LeftBradycardiaCardiomegalyPacemaker, ArtificialVoltage-Sensitive Dye ImagingHeart SeptumCardiac Output, LowAconitineAtrial Premature ComplexesEndocardiumPropafenoneEther-A-Go-Go Potassium ChannelsEncainideSyncopeBody Surface Potential MappingHeart InjuriesConnexin 43Tetralogy of FallotAtrioventricular NodeElectrophysiologyEpinephrineRetrospective StudiesSodium ChannelsVentricular RemodelingPredictive Value of TestsRats, WistarSympathetic Nervous SystemSinoatrial NodeIsoproterenol