Pulmonary VeinsVeinsCatheter AblationAtrial FibrillationPulmonary Veno-Occlusive DiseaseCerebral VeinsPortal VeinHeart AtriaPhlebographyFemoral VeinSaphenous VeinElectrophysiologic Techniques, CardiacVaricose VeinsJugular VeinsVenous InsufficiencyCryosurgeryPopliteal VeinVascular MalformationsVenous PressureCorrosion CastingVena Cava, SuperiorHepatic VeinsIliac VeinHeart Conduction SystemPortal SystemRenal VeinsBody Surface Potential MappingSplenic VeinTachycardia, Ectopic AtrialMesenteric VeinsTreatment OutcomeCardiac CathetersVena Cava, InferiorAzygos VeinVenous ThrombosisVenous ValvesCoronary SinusUmbilical VeinsRecurrenceSubclavian VeinConstriction, PathologicDogsMagnetic Resonance AngiographyImaging, Three-DimensionalThrombophlebitisTomography, X-Ray ComputedUltrasonography, Doppler, DuplexTomography, Spiral ComputedUltrasonography, Doppler, ColorVenae CavaeLegBrachiocephalic VeinsVaricose UlcerFollow-Up StudiesTachycardia, ParoxysmalFluoroscopyPortographyAngiographyScimitar SyndromeKlippel-Trenaunay-Weber SyndromeAtrial SeptumAnti-Arrhythmia AgentsSurgery, Computer-AssistedBlood Flow VelocityElectrocardiographyAutonomic DenervationCranial SinusesAtrial Premature ComplexesSinus Thrombosis, IntracranialAtrial AppendageAtrial FunctionBreath HoldingTime FactorsAtrial Function, LeftEchocardiography, TransesophagealDura MaterAtrial FlutterFeasibility StudiesElectrocardiography, AmbulatoryDissectionEmbolism, AirCardiac Pacing, ArtificialProspective StudiesElectrophysiological PhenomenaCardiac Complexes, PrematureRetrospective StudiesAdrenergic AgonistsCatheterizationHypertension, PortalPulmonary ArteryVascular DiseasesUltrasonography, PrenatalCatheterization, Central VenousSinoatrial NodePulmonary CirculationVascular Surgical ProceduresLymphangiectasisTachycardiaHeart Septal Defects, AtrialAnticoagulants