TachycardiaHypotensionTachycardia, VentricularTachycardia, SupraventricularOxygenHypotension, ControlledTachycardia, Atrioventricular Nodal ReentryTachycardia, ParoxysmalTachycardia, Ectopic AtrialTachycardia, SinusHypotension, OrthostaticElectrocardiographyCatheter AblationIntracranial HypotensionTachycardia, Ectopic JunctionalPostural Orthostatic Tachycardia SyndromeOxygen ConsumptionTachycardia, ReciprocatingTachycardia, Sinoatrial Nodal ReentryReactive Oxygen SpeciesHeart Conduction SystemElectrophysiologic Techniques, CardiacHeart RateCardiac Pacing, ArtificialAnti-Arrhythmia AgentsAtrioventricular NodeBlood PressureBundle of HisBody Surface Potential MappingArrhythmias, CardiacVentricular FibrillationWolff-Parkinson-White SyndromeBradycardiaHemodynamicsSyncopeDefibrillators, ImplantableAmiodaroneOxygen Inhalation TherapyElectrocardiography, AmbulatoryFlecainideVentricular Premature ComplexesHeart AtriaSinglet OxygenCryosurgeryTreatment OutcomeDogsTime FactorsProcainamideEndocardiumHeart VentriclesHeart BlockAtrial FlutterBundle-Branch BlockPre-Excitation SyndromesPost-Exercise HypotensionAccessory Atrioventricular BundleCardiac Complexes, PrematureElectrophysiologyFollow-Up StudiesTrimethaphanAutonomic Nervous System DiseasesDeath, Sudden, CardiacElectric CountershockTilt-Table TestEpicardial MappingMidodrineAnesthesiaAnesthesia, ObstetricalHeartEphedrineCardiac OutputProspective StudiesAdrenergic beta-AntagonistsSympathetic Nervous SystemPostureRecurrenceAtrial FibrillationSotalolPropranololCardiomyopathiesRetrospective StudiesHydrops FetalisAnesthesia, SpinalVascular ResistanceShockHypovolemiaArrhythmogenic Right Ventricular DysplasiaAutonomic Nervous SystemOxygen IsotopesCardiovascular SystemPacemaker, ArtificialDose-Response Relationship, DrugCerebrovascular CirculationPartial PressureVerapamilMyocardial InfarctionAnoxiaPericardiumNitroprussideShock, Septic