Tachycardia, SupraventricularTachycardiaTachycardia, ParoxysmalTachycardia, VentricularHeart AtriaTachycardia, Atrioventricular Nodal ReentryTachycardia, SinusElectrocardiographyTachycardia, Ectopic AtrialCatheter AblationAtrioventricular NodeTachycardia, Ectopic JunctionalAnti-Arrhythmia AgentsHeart Conduction SystemWolff-Parkinson-White SyndromeArrhythmias, CardiacElectrophysiologic Techniques, CardiacAtrial Premature ComplexesCardiac Pacing, ArtificialBundle of HisAtrial FlutterHydrops FetalisFlecainideAtrial FibrillationTachycardia, Sinoatrial Nodal ReentryElectrocardiography, AmbulatoryAmiodaroneDigoxinHeart RateCardiac Complexes, PrematurePostural Orthostatic Tachycardia SyndromePre-Excitation SyndromesAccessory Atrioventricular BundleBody Surface Potential MappingAtrial FunctionTachycardia, ReciprocatingFetal DiseasesVentricular FibrillationDefibrillators, ImplantableElectric CountershockHeart BlockSotalolVentricular Premature ComplexesElectrocoagulationHeart VentriclesTreatment OutcomeSinoatrial NodeProcainamideFollow-Up StudiesElectrophysiologyHeartAtrioventricular BlockSyncopeVerapamilPropafenonePulmonary VeinsDogsHeart Rate, FetalPacemaker, ArtificialEchocardiographyRecurrenceBradycardiaBundle-Branch BlockRefractory Period, ElectrophysiologicalHeart Defects, CongenitalRetrospective StudiesAntazolineDisopyramideDeath, Sudden, CardiacTime FactorsAdrenergic beta-AntagonistsEndocardiumAtrial Function, RightAdenosineCardiac Surgical ProceduresHydroxyzineCardiac CatheterizationCardiomyopathy, DilatedCryosurgeryCardiomyopathiesFinancial AuditTricuspid AtresiaHemodynamicsInfant, NewbornProspective StudiesIsoproterenolEbstein AnomalyPostoperative ComplicationsSick Sinus SyndromeFetal DistressArrhythmia, SinusFetal HeartHeterotaxy SyndromeFluoroscopyPropanolaminesLavandulaBlood PressureEpicardial MappingEquipment FailureInjections, Intravenous