Cardiac ElectrophysiologyArrhythmias, CardiacElectrophysiological ProcessesElectrophysiologic Techniques, CardiacEpicardial MappingModels, CardiovascularHeartMyocytes, CardiacHeart Conduction SystemElectrophysiologyElectrocardiographyVoltage-Sensitive Dye ImagingElectrophysiological PhenomenaAction PotentialsHeart VentriclesAtrioventricular NodeLong QT SyndromeCatheter AblationMyocardiumHeart RateCardiac OutputComputer SimulationDeath, Sudden, CardiacArrhythmia, SinusPotassium ChannelsCardiac Surgical ProceduresCardiac Pacing, ArtificialTachycardia, VentricularAnti-Arrhythmia AgentsVentricular FibrillationHeart DiseasesCardiomegalyMyocardial ContractionAlgorithmsCardiac CatheterizationHeart AtriaTime FactorsCardiac TamponadeHeart ArrestDogsHeart FailureAtrial FibrillationCardiomyopathiesVentricular Premature ComplexesTachycardiaMyocardial InfarctionElectrocardiography, AmbulatoryEchocardiographyTachycardia, SupraventricularPatch-Clamp TechniquesDefibrillators, ImplantableNAV1.5 Voltage-Gated Sodium ChannelHemodynamicsCardiac Imaging TechniquesMyoblasts, CardiacVentricular Function, LeftCalciumVentricular FunctionMyocardial IschemiaRats, Sprague-DawleyCardiac Complexes, PrematureCardiac MyosinsCardiac GlycosidesDisease Models, AnimalMembrane PotentialsVentricular DysfunctionTreatment OutcomeCardiac Output, LowPacemaker, ArtificialPericardiumSodium ChannelsElectric CountershockBlood PressureBody Surface Potential MappingVentricular RemodelingHeart BlockAtrial FlutterHeart Defects, CongenitalHeart TransplantationOut-of-Hospital Cardiac ArrestStroke VolumeCardiomyopathy, DilatedCardiac VolumeProspective StudiesTroponin IFollow-Up StudiesEther-A-Go-Go Potassium ChannelsCardiotonic AgentsVentricular Dysfunction, LeftAtrial FunctionHeart Function TestsCells, CulturedMyocardial Reperfusion InjuryPotassium Channels, Voltage-GatedBradycardiaPurkinje FibersRetrospective StudiesRisk Factors