Heart AtriaPulmonary VeinsAtrial FunctionAtrial FibrillationAtrial Function, LeftCatheter AblationHeart NeoplasmsElectrophysiologic Techniques, CardiacVentricular Function, LeftHeart Conduction SystemMyocardial ContractionEchocardiographyHeartVena Cava, SuperiorEchocardiography, TransesophagealMyxomaDogsMitral Valve StenosisBody Surface Potential MappingAtrial Function, RightHeart VentriclesVentricular Dysfunction, LeftMitral ValveAtrial AppendageCardiac Pacing, ArtificialElectrocardiographyAtrial SeptumCoronary SinusCor TriatriatumHeart SeptumHeart Septal Defects, AtrialGuinea PigsHypertrophy, Left VentricularAtrial FlutterRefractory Period, ElectrophysiologicalPericardiumHeart AneurysmMitral Valve InsufficiencyCardiac Surgical ProceduresTreatment OutcomeSinoatrial NodeEndocardiumFistulaTachycardia, Ectopic AtrialHeart RateCardiac CatheterizationMyocardiumAutonomic DenervationAnti-Arrhythmia AgentsHeart DiseasesRheumatic Heart DiseaseHemodynamicsTachycardiaStroke VolumeEchocardiography, Doppler, ColorAtrioventricular NodeHeart Valve DiseasesVagus NerveTomography, X-Ray ComputedDiastoleIsoproterenolHeart FailureAtrial Natriuretic FactorPacemaker, ArtificialCardiac VolumePulmonary ArteryAction PotentialsCardiotonic AgentsMitral Valve ProlapsePulmonary CirculationTime FactorsHeart InjuriesBlood PressureVentricular FunctionSystoleCardiopulmonary BypassSurgery, Computer-AssistedHeart BlockFollow-Up StudiesAngiocardiographyTachycardia, ParoxysmalAtrial Premature ComplexesEchocardiography, Three-DimensionalVena Cava, InferiorHeart Septal DefectsFluoroscopyCardiac CathetersCoronary CirculationEsophageal FistulaHeart Defects, CongenitalProlapseModels, CardiovascularMyxosarcomaEchocardiography, DopplerBundle of HisArrhythmias, CardiacElectric StimulationScimitar SyndromeCryosurgeryHeart Valve Prosthesis Implantation