MyocardiumHeartHeart RateHeart FailureMyocardial ContractionMyocardial StunningHeart DiseasesMyocardial IschemiaHeart Defects, CongenitalHeart TransplantationFetal HeartMyocardial InfarctionMyocytes, CardiacHeart AtriaMyocardial Reperfusion InjuryDogsHeart ValvesHeart VentriclesCardiotonic AgentsHemodynamicsVentricular Function, LeftCardiomyopathiesCoronary DiseaseCoronary CirculationVentricular RemodelingHeart Function TestsCardiomegalyEchocardiographyHeart Arrest, InducedTime FactorsMyocardial ReperfusionCardiomyopathy, DilatedHeart BlockPerfusionVentricular Dysfunction, LeftDisease Models, AnimalIschemic Preconditioning, MyocardialRats, Sprague-DawleyMyocarditisStroke VolumeCardiac Output, LowRats, WistarModels, CardiovascularHeart InjuriesTissue SurvivalHeart SeptumPericardiumDobutamineCalciumVentricular FunctionRabbitsCoronary VesselsSystoleVentricular PressureOxygen ConsumptionCreatine KinaseFibrosisIodobenzenesDiastoleAdrenergic beta-AntagonistsIsolated Noncompaction of the Ventricular MyocardiumTomography, Emission-Computed, Single-PhotonSarcolemmaCardiac Pacing, ArtificialSwineChronic DiseaseRNA, MessengerHypertrophy, Left VentricularMyofibrilsHeart Failure, SystolicAdrenergic beta-AgonistsCardiac MyosinsVentricular DysfunctionEndomyocardial FibrosisReceptors, Adrenergic, betaRheumatic Heart DiseaseMagnetic Resonance Imaging, CineHeart, ArtificialTroponin IRisk FactorsHeart Conduction SystemHeart ArrestProspective StudiesImmunohistochemistryOrganotechnetium CompoundsHeart NeoplasmsAction PotentialsCells, CulturedHeart Valve ProsthesisTreatment OutcomeExercise TestDose-Response Relationship, DrugThallium RadioisotopesHeart Failure, DiastolicFollow-Up StudiesPropanolaminesModels, AnimalHeart Rate, FetalContrast MediaSarcoplasmic Reticulum