CardiomegalyHeartHydrops FetalisCardiomegaly, Exercise-InducedHeart RateHeart FailureJamaicaCardiomyopathiesRadiography, ThoracicHeart Defects, CongenitalArteriovenous FistulaPericardial EffusionChagas CardiomyopathyFetal DiseasesHeart NeoplasmsMyocardiumUltrasonography, PrenatalEchocardiographyFatal OutcomeElectrocardiographyHeart DiseasesHeart TransplantationPregnancyFetal HeartRetrospective StudiesInfant, NewbornPrognosisHeart ValvesHeart AtriaHypertensionHeart BlockHeart Arrest, InducedHeart Function TestsMyocardial ContractionMyocardial IschemiaMyocytes, CardiacCoronary DiseaseHemodynamicsCardiac Output, LowVentricular Function, LeftTime FactorsHeart, ArtificialHeart Failure, SystolicPerfusionCardiomyopathy, DilatedMyocardial InfarctionHeart InjuriesHeart Rate, FetalHeart SeptumCardiotonic AgentsRheumatic Heart DiseaseStroke VolumeMyocardial Reperfusion InjuryHeart ArrestRisk FactorsHeart Valve ProsthesisVentricular Dysfunction, LeftAdrenergic beta-AntagonistsHeart Failure, DiastolicAmerican Heart AssociationVentricular RemodelingDogsProspective StudiesOxygen ConsumptionFollow-Up StudiesAutonomic Nervous SystemCardiac Pacing, ArtificialHeart Septal DefectsHypoplastic Left Heart SyndromeRats, Sprague-DawleyChronic DiseaseNational Heart, Lung, and Blood Institute (U.S.)Natriuretic Peptide, BrainDisease Models, AnimalRats, WistarVentricular PressureTreatment OutcomeExercise Test