Arrhythmias, CardiacTachycardiaTachycardia, VentricularTachycardia, SupraventricularHeartElectrocardiographyCardiac ElectrophysiologyVentricular FibrillationElectrocardiography, AmbulatoryAnti-Arrhythmia AgentsVentricular Premature ComplexesTachycardia, Atrioventricular Nodal ReentryTachycardia, Ectopic AtrialTachycardia, ParoxysmalHeart Conduction SystemTachycardia, SinusHeart RateDeath, Sudden, CardiacCatheter AblationAtrial FibrillationArrhythmia, SinusHeart VentriclesTachycardia, Ectopic JunctionalElectrophysiologic Techniques, CardiacCardiac Pacing, ArtificialPostural Orthostatic Tachycardia SyndromeAction PotentialsTime FactorsTachycardia, Sinoatrial Nodal ReentryTachycardia, ReciprocatingAtrioventricular NodeHeart AtriaHeart FailureBody Surface Potential MappingHeart BlockDefibrillators, ImplantableBundle of HisCardiac Complexes, PrematureHeart DiseasesHeart Defects, CongenitalWolff-Parkinson-White SyndromeAmiodaroneAtrial FlutterFlecainideMyocardiumDogsHeart TransplantationElectric CountershockEndocardiumFollow-Up StudiesLong QT SyndromeProcainamideTreatment OutcomeCardiomyopathiesMyocardial InfarctionMyocardial IschemiaElectrophysiologyFetal HeartSyncopeVentricular DysfunctionMyocytes, CardiacCryosurgeryAdrenergic beta-AntagonistsHemodynamicsBundle-Branch BlockEpicardial MappingPre-Excitation SyndromesSotalolEchocardiographyPacemaker, ArtificialMyocardial ContractionCardiomyopathy, DilatedBradycardiaTorsades de PointesHeart ArrestPropafenoneDeath, SuddenAccessory Atrioventricular BundleArrhythmogenic Right Ventricular DysplasiaHeart ValvesProspective StudiesNAV1.5 Voltage-Gated Sodium ChannelModels, CardiovascularRecurrencePericardiumDigitalis GlycosidesAutonomic Nervous SystemAtrial Premature ComplexesAtrioventricular BlockStroke VolumeMyocardial Reperfusion InjuryRetrospective StudiesCoronary DiseaseSinoatrial NodePropranololVentricular Function, LeftHeart Function TestsRisk FactorsMexiletineVentricular Dysfunction, Left