Ventricular FunctionElectrocardiographyHeart Conduction SystemLong QT SyndromeAction PotentialsArrhythmias, CardiacTorsades de PointesHeart VentriclesAnti-Arrhythmia AgentsMagnetocardiographyRefractory Period, ElectrophysiologicalSotalolHeart RatePericardiumPotassium Channels, Voltage-GatedCardiac Pacing, ArtificialHeartDogsKCNQ1 Potassium ChannelBody Surface Potential MappingEther-A-Go-Go Potassium ChannelsMexiletineTachycardia, VentricularEndocardiumPhenethylaminesDelayed Rectifier Potassium ChannelsPotassium ChannelsVentricular FibrillationVectorcardiographyPotassium Channel BlockersElectrophysiologyElectrophysiologic Techniques, CardiacElectrocardiography, AmbulatoryCardiac Complexes, PrematureKv1.5 Potassium ChannelDeath, Sudden, CardiacGuinea Pigs4-AminopyridineChromansMyocytes, CardiacPatch-Clamp TechniquesMembrane PotentialsTime FactorsSulfonamidesRabbitsAtrial FibrillationDrug-Related Side Effects and Adverse ReactionsPropanolaminesSodium ChannelsMyocardiumMyocardial ContractionPredictive Value of TestsOptical Rotatory DispersionLinear ModelsDrug Evaluation, PreclinicalModels, CardiovascularBrugada SyndromeVentricular Function, LeftReference ValuesHeart FailurePotassiumPurkinje FibersDose-Response Relationship, DrugExercise TestAtrial FunctionHeart AtriaQuinidineCase-Control StudiesSex FactorsRisk AssessmentCalciumElectric ConductivityNAV1.5 Voltage-Gated Sodium ChannelPovidoneCardiac ElectrophysiologyVoltage-Sensitive Dye ImagingProspective StudiesKCNQ Potassium ChannelsRisk FactorsTetraethylammoniumShal Potassium ChannelsIon Channel GatingSodium Channel BlockersRomano-Ward SyndromeComputer SimulationPapillary MusclesRetrospective StudiesChemistry, PharmaceuticalCalcium Channels, L-TypeSodiumElectric StimulationIon ChannelsCalorimetry, Differential ScanningTetraethylammonium CompoundsAcetanilidesBarium CompoundsKineticsMicroelectrodesMethylcelluloseFlecainide