HeartMyocytes, CardiacHeart DiseasesHeart RateHeart Defects, CongenitalMyocardiumCoronary DiseaseHeart FailureMyocardial IschemiaRheumatic Heart DiseaseMyocardial ContractionCardiomegalyRisk FactorsCells, CulturedHeart TransplantationFetal HeartAnimals, NewbornMyocardial InfarctionHeart AtriaCardiomyopathiesRats, Sprague-DawleyHeart ValvesHeart VentriclesTime FactorsRats, WistarCardiotonic AgentsCarcinoid Heart DiseaseMyocardial Reperfusion InjuryProspective StudiesCardiomyopathy, DilatedCalciumFollow-Up StudiesEchocardiographyCyanosisHeart Function TestsHeart BlockVentricular RemodelingCardiovascular DiseasesCohort StudiesIsoproterenolSignal TransductionMitochondria, HeartVentricular Function, LeftHemodynamicsSarcomeresHeart Valve DiseasesBiological MarkersCardiac MyosinsDisease Models, AnimalCell SizeApoptosisGATA4 Transcription FactorEmbryonic Stem CellsCalcium Channels, L-TypeMyocarditisRisk AssessmentCell DifferentiationIncidenceAge FactorsSarcoplasmic Reticulum Calcium-Transporting ATPasesHeart Arrest, InducedArrhythmias, CardiacMuscle CellsSarcolemmaRiskAdrenergic beta-AgonistsConnexin 43HypertrophyHeart InjuriesMice, Inbred C57BLVentricular Dysfunction, LeftChronic DiseaseCause of DeathSodium-Calcium ExchangerCalcium SignalingHeart Septal DefectsMuscle ProteinsAdrenergic beta-AntagonistsCase-Control StudiesMyoblasts, CardiacSex FactorsProportional Hazards ModelsPrevalenceRNA, MessengerSarcoplasmic ReticulumStroke VolumeElectrocardiographyTreatment OutcomeCardiac Output, LowVentricular MyosinsMice, KnockoutMice, TransgenicAngina PectorisDose-Response Relationship, DrugUnited StatesRetrospective StudiesModels, CardiovascularRheumatic FeverInfant, NewbornPredictive Value of Tests