Heart RateHeartHeart FailureHeart Rate, FetalBlood PressureAutonomic Nervous SystemHeart DiseasesHemodynamicsHeart TransplantationHeart Defects, CongenitalTime FactorsFetal HeartReproducibility of ResultsSympathetic Nervous SystemElectrocardiographyElectrocardiography, AmbulatoryBaroreflexHeart AtriaExercise TestAdrenergic beta-AntagonistsOxygen ConsumptionMyocardiumMyocardial ContractionHeart ValvesDogsHeart BlockTelemetryHeart Function TestsProspective StudiesReference ValuesRespirationParasympathetic Nervous SystemStroke VolumeBradycardiaVentricular Function, LeftCardiac OutputPropranololMyocardial IschemiaExercisePhysical ExertionCoronary DiseaseCardiovascular Physiological PhenomenaRestSensitivity and SpecificityRisk FactorsTachycardiaCardiovascular SystemEchocardiographyPostureAtropinePredictive Value of TestsPropanolaminesCardiotonic AgentsPressoreceptorsNorepinephrineBlood Flow VelocityHeart Arrest, InducedSignal Processing, Computer-AssistedModels, CardiovascularRegional Blood FlowMyocardial InfarctionDose-Response Relationship, DrugFollow-Up StudiesSinoatrial NodeAnalysis of VarianceOxygenDouble-Blind MethodMonitoring, PhysiologicSystoleReflexRats, Sprague-DawleyBody TemperatureAutonomic Nervous System DiseasesSupine PositionMyocytes, CardiacTreatment OutcomeCardiac Output, LowObserver VariationDiastoleCardiac Pacing, ArtificialArrhythmia, SinusCircadian RhythmRats, WistarIsoproterenolMetoprololBiological MarkersEpinephrineVentricular Dysfunction, LeftHypertensionCardiomyopathy, DilatedDisease Models, AnimalLinear ModelsRegression AnalysisAlgorithmsChronic DiseaseRabbitsArrhythmias, CardiacCross-Over StudiesCatecholaminesHypotension