Tachycardia, SupraventricularTachycardiaTachycardia, ParoxysmalTachycardia, VentricularTachycardia, Atrioventricular Nodal ReentryElectrocardiographyTachycardia, SinusTachycardia, Ectopic AtrialCatheter AblationTachycardia, Ectopic JunctionalAnti-Arrhythmia AgentsAtrioventricular NodeArrhythmias, CardiacHeart Conduction SystemWolff-Parkinson-White SyndromeHeart RateAtrial Premature ComplexesCardiac Complexes, PrematureElectrophysiologic Techniques, CardiacCardiac Pacing, ArtificialLeechesBundle of HisHydrops FetalisFlecainideAtrial FlutterTachycardia, Sinoatrial Nodal ReentryElectrocardiography, AmbulatoryAmiodaroneDigoxinHeartPostural Orthostatic Tachycardia SyndromePre-Excitation SyndromesAccessory Atrioventricular BundleAtrial FibrillationTachycardia, ReciprocatingFetal DiseasesHeart Rate, FetalBody Surface Potential MappingHeart AtriaDefibrillators, ImplantableVentricular FibrillationVentricular Premature ComplexesElectric CountershockSinoatrial NodeSotalolCardiotocographyHeart BlockGanglia, InvertebrateElectrocoagulationElectrophysiologyHeart VentriclesProcainamideTreatment OutcomeArrhythmia, SinusFollow-Up StudiesTime FactorsAtrioventricular BlockSyncopePropafenoneVerapamilCardiac-Gated Imaging TechniquesSignal Processing, Computer-AssistedFMRFamideMyocardial ContractionBundle-Branch BlockRecurrenceBradycardiaBelizePacemaker, ArtificialAntazolineBlood PressureRetrospective StudiesDeath, Sudden, CardiacEchocardiographyModels, CardiovascularDisopyramideUltrasonography, PrenatalHydroxyzineHeart Defects, CongenitalOctopodiformesFourier AnalysisFinancial AuditAdrenergic beta-AntagonistsSympathetic Nervous SystemMyocardiumBrain DeathCardiomyopathiesDogsAdenosineCardiomyopathy, DilatedCryosurgeryPeriodicityReproducibility of ResultsTricuspid AtresiaAlgorithmsInfant, NewbornGestational SacCardiac Surgical ProceduresAtrial FunctionProspective Studies