Heart RateHeartRegional Blood FlowHeart Rate, FetalBlood Flow VelocityHeart FailureBlood PressureAutonomic Nervous SystemHeart DiseasesFlow CytometryHeart TransplantationHeart Defects, CongenitalHemodynamicsFetal HeartSympathetic Nervous SystemTime FactorsElectrocardiography, AmbulatoryBaroreflexHeart AtriaElectrocardiographyAdrenergic beta-AntagonistsHeart ValvesOxygen ConsumptionExercise TestMyocardiumPulsatile FlowMyocardial ContractionHeart BlockHeart Function TestsParasympathetic Nervous SystemTelemetryPropranololRespirationCardiac OutputDogsBradycardiaStroke VolumeMyocardial IschemiaVentricular Function, LeftPhysical ExertionCoronary DiseaseCardiovascular Physiological PhenomenaExerciseRestTachycardiaModels, CardiovascularAtropineGene FlowCardiovascular SystemCoronary CirculationPressoreceptorsNorepinephrinePropanolaminesCardiotonic AgentsHeart Arrest, InducedEchocardiographyProspective StudiesMyocardial InfarctionSinoatrial NodeReflexDose-Response Relationship, DrugAutonomic Nervous System DiseasesPostureRats, Sprague-DawleyReference ValuesCardiac Output, LowMyocytes, CardiacCardiac Pacing, ArtificialSystoleArrhythmia, SinusDouble-Blind MethodSupine PositionDiastoleIsoproterenolRisk FactorsMetoprololOxygenEpinephrineRats, WistarBody TemperaturePerfusionSignal Processing, Computer-AssistedBlood CirculationCardiomyopathy, DilatedCerebrovascular CirculationHypotensionVasodilator AgentsAnesthesiaFollow-Up StudiesDisease Models, AnimalTreatment OutcomeTilt-Table TestVentricular Dysfunction, LeftPhenylephrineCatecholaminesCircadian RhythmPredictive Value of TestsArrhythmias, CardiacAtenololCardiomegaly