Atrial Function, LeftAtrial FunctionHeart AtriaAtrial Function, RightAtrial FibrillationEchocardiography, DopplerVentricular Function, LeftMyocardial ContractionEchocardiographyElectric CountershockEchocardiography, Doppler, PulsedPulmonary VeinsPericardiectomyEchocardiography, TransesophagealHeart Function TestsStroke VolumeVentricular FunctionVentricular Dysfunction, LeftHemodynamicsObserver VariationCatheter AblationHeart NeoplasmsBlood Flow VelocityElectrophysiologic Techniques, CardiacHeart VentriclesHeartHypertrophy, Left VentricularHeart Conduction SystemDogsVena Cava, SuperiorMitral Valve StenosisMitral ValveBody Surface Potential MappingMyxomaElectrocardiographyAtrial AppendageCardiac Pacing, ArtificialCoronary SinusAtrial SeptumHeart SeptumHeart AneurysmTreatment OutcomeHeart Septal Defects, AtrialPericardiumMyocardiumCor TriatriatumCardiac Surgical ProceduresCardiac CatheterizationEndocardiumHeart RateGuinea PigsAtrial FlutterRefractory Period, ElectrophysiologicalFistulaDiastoleMitral Valve InsufficiencySinoatrial NodeHeart DiseasesTachycardia, Ectopic AtrialHeart FailureEchocardiography, Doppler, ColorAnti-Arrhythmia AgentsAutonomic DenervationSystoleTachycardiaCardiac VolumeTomography, X-Ray ComputedTime FactorsRheumatic Heart DiseaseHeart Valve DiseasesBlood PressureAtrioventricular Node