Heart RateHeartHeart Rate, FetalHeart FailureAutonomic Nervous SystemBlood PressureHeart DiseasesHeart TransplantationHeart Defects, CongenitalHemodynamicsFetal HeartSympathetic Nervous SystemElectrocardiography, AmbulatoryBaroreflexHeart AtriaElectrocardiographyTime FactorsAdrenergic beta-AntagonistsHeart ValvesExercise TestMyocardial ContractionMyocardiumHeart BlockOxygen ConsumptionTelemetryHeart Function TestsDogsParasympathetic Nervous SystemBradycardiaPropranololRespirationStroke VolumeMonitoring, PhysiologicMyocardial IschemiaVentricular Function, LeftCardiovascular Physiological PhenomenaTachycardiaExercisePhysical ExertionCoronary DiseaseCardiac OutputCardiovascular SystemRestAtropinePressoreceptorsPropanolaminesCardiotonic AgentsHeart Arrest, InducedNorepinephrineSinoatrial NodeProspective StudiesEchocardiographyReflexAutonomic Nervous System DiseasesMyocardial InfarctionMyocytes, CardiacArrhythmia, SinusRisk FactorsPostureCardiac Output, LowSignal Processing, Computer-AssistedCardiac Pacing, ArtificialDose-Response Relationship, DrugIsoproterenolMetoprololSupine PositionDouble-Blind MethodModels, CardiovascularRats, Sprague-DawleySystoleBody TemperatureEpinephrineReference ValuesCardiomyopathy, DilatedRats, WistarFetal MonitoringDiastoleFollow-Up StudiesVentricular Dysfunction, LeftRegional Blood FlowArrhythmias, CardiacCircadian RhythmHypotensionReproducibility of ResultsTreatment OutcomeCatecholaminesAnesthesiaAnti-Arrhythmia AgentsTilt-Table TestAtenololCardiomegalyOxygenPredictive Value of TestsPhenylephrineDisease Models, AnimalMyocardial Reperfusion InjuryConsciousnessCross-Over StudiesCardiomyopathiesHeart Failure, Systolic