Atrial AppendageEchocardiography, TransesophagealHeart AtriaAtrial Function, LeftAtrial FibrillationThromboembolismElectric CountershockThrombosisHeart AneurysmSeptal Occluder DeviceAtrial FunctionHeart DiseasesCatheter AblationAtrial SeptumAtrial FlutterProstheses and ImplantsMitral Valve StenosisCardiac Surgical ProceduresCardiac Pacing, ArtificialPulmonary VeinsAnticoagulantsRheumatic Heart DiseaseAtrial Function, RightBlood Flow VelocityTachycardia, Ectopic AtrialElectrophysiologic Techniques, CardiacEmbolismCardiac CatheterizationFeasibility StudiesSick Sinus SyndromePericardiumTreatment OutcomeEchocardiographyTherapeutic OcclusionWarfarinEchocardiography, Doppler, PulsedDogsCardiac CathetersEchocardiography, Three-DimensionalVena Cava, SuperiorStrokeHeart Valve DiseasesExtremitiesPericardial EffusionRefractory Period, ElectrophysiologicalCarcinoma, Skin AppendageMitral ValveHeart Conduction SystemCoronary ThrombosisEchocardiography, DopplerElectrocardiographyBalloon OcclusionSinoatrial NodeCefamandolePacemaker, ArtificialHeart BlockIntracranial EmbolismTime FactorsHeart SeptumMyocardiumPremedicationFollow-Up StudiesHeart Septal DefectsEndocardiumMyocardial StunningProspective StudiesBalloon ValvuloplastyHeart Defects, CongenitalSuture TechniquesSuturesFluoroscopyCardiopulmonary BypassObserver Variation