DobutamineCardiotonic AgentsEchocardiography, StressMyocardial ContractionEchocardiographyAdrenergic beta-AgonistsExercise TestMyocardial StunningAdrenergic beta-1 Receptor AgonistsVentricular Function, LeftHemodynamicsMyocardial IschemiaVentricular Dysfunction, LeftHydrazonesCoronary DiseaseCoronary CirculationHeartTissue SurvivalThallium RadioisotopesTomography, Emission-Computed, Single-PhotonTechnetium Tc 99m SestamibiAmrinoneMilrinoneCoronary AngiographySensitivity and SpecificityHeart RateDipyridamolePredictive Value of TestsStroke VolumePyridazinesEnoximoneElectrocardiographyDogsMyocardial RevascularizationMyocardiumMagnetic Resonance Imaging, CineCardiac OutputSympathomimeticsCatecholaminesAtropineMyocardial InfarctionSystolePropanolaminesFeasibility StudiesOxygen ConsumptionAdrenergic beta-AntagonistsObserver VariationBlood PressureCardiomyopathy, DilatedReceptors, Adrenergic, betaProspective StudiesVasodilator AgentsRadionuclide VentriculographyHistory, Early Modern 1451-1600Tomography, Emission-ComputedDiastoleRadiopharmaceuticalsEchocardiography, DopplerInfusions, Intravenous