Heart AtriaAtrial Natriuretic FactorMyocardiumMyocytes, CardiacHeartCardiac OutputAtrial FunctionCardiac Surgical ProceduresArrhythmias, CardiacDeath, Sudden, CardiacMyocardial ContractionCardiac Pacing, ArtificialHeart VentriclesCardiomegalyHeart DiseasesHeart Conduction SystemCardiac TamponadeCardiac CatheterizationAtrial FibrillationHeart NeoplasmsElectrocardiographyHeart RateDogsEchocardiographyAtrial Function, RightPulmonary VeinsHeart ArrestHeart FailureElectrophysiologic Techniques, CardiacCardiomyopathiesCardiac MyosinsCardiac Imaging TechniquesHemodynamicsMyoblasts, CardiacCardiac GlycosidesSinoatrial NodeCardiac VolumeHeart Defects, CongenitalGuinea PigsCatheter AblationCardiac Output, LowHeart TransplantationVentricular Function, LeftCardiotonic AgentsVentricular RemodelingIsoproterenolMyocardial InfarctionOut-of-Hospital Cardiac ArrestTime FactorsModels, CardiovascularBlood PressureTreatment OutcomeFetal HeartTroponin IVentricular FunctionStroke VolumeMyxomaPericardiumVena Cava, SuperiorHeart InjuriesCardiomyopathy, DilatedAction PotentialsAtrial Function, LeftCardiac ElectrophysiologyCalciumHeart Function TestsAtrioventricular NodePacemaker, ArtificialEchocardiography, TransesophagealCardiac Resynchronization TherapyAnti-Arrhythmia AgentsFibrosisRats, Sprague-DawleyRefractory Period, ElectrophysiologicalVentricular Dysfunction, LeftMyocardial IschemiaEndocardiumCardiopulmonary BypassDisease Models, AnimalTroponin TAtrial FlutterVagus NerveCardiopulmonary ResuscitationCardiac Care FacilitiesProspective StudiesBody Surface Potential MappingTachycardiaHeart BlockAtrial AppendageFollow-Up StudiesHeart ValvesElectrophysiologyRats, WistarCells, CulturedRabbitsAdrenergic beta-AntagonistsMuscle ProteinsAdrenergic beta-Agonists