Heart FailureHeart-Assist DevicesVentricular Function, LeftHeartVentricular Dysfunction, LeftStroke VolumeHeart TransplantationVentricular Function, RightHeart RateHeart VentriclesHemodynamicsCardiomyopathy, DilatedEchocardiographyMyocytes, CardiacMyocardiumVentricular FunctionCardiac Output, LowMyocardial ContractionTreatment OutcomeHeart DiseasesCardiomyopathiesMyocardial InfarctionVentricular Dysfunction, RightTime FactorsCardiac OutputProsthesis ImplantationVentricular RemodelingShock, CardiogenicEquipment DesignCardiac Surgical ProceduresFollow-Up StudiesSystoleCardiac Pacing, ArtificialHeart Function TestsCardiotonic AgentsHeart Failure, SystolicProspective StudiesNatriuretic Peptide, BrainDiastoleElectrocardiographyCardiac CatheterizationMyocardial IschemiaRetrospective StudiesEchocardiography, DopplerDevice RemovalHeart Failure, DiastolicHeart Defects, CongenitalArrhythmias, CardiacCardiomegalyVentricular PressureChronic DiseaseProsthesis DesignAdrenergic beta-AntagonistsAssisted CirculationExercise TestBlood PressurePredictive Value of TestsHeart AtriaHypertrophy, Left VentricularRisk FactorsPrognosisEquipment FailureDeath, Sudden, CardiacDogsSeverity of Illness IndexExtracorporeal Membrane OxygenationRadionuclide VentriculographyDisease Models, AnimalCardiac VolumeCoronary DiseaseVentricular DysfunctionIntra-Aortic Balloon PumpingRisk AssessmentHeart, ArtificialTreatment FailureMyocarditisCoronary CirculationCardiovascular AgentsGated Blood-Pool ImagingBiological MarkersCardiac Resynchronization TherapySurvival AnalysisRecovery of FunctionSurvival RatePulmonary Wedge PressurePacemaker, ArtificialEquipment SafetyOxygen ConsumptionMitral Valve InsufficiencyRadionuclide AngiographyAngiotensin-Converting Enzyme InhibitorsModels, CardiovascularPropanolaminesDevice ApprovalPostoperative ComplicationsDobutamineExercise ToleranceEchocardiography, TransesophagealCoronary Artery BypassDefibrillators, Implantable