Splenic VeinSplanchnic CirculationBudd-Chiari SyndromeMyeloproliferative DisordersPortal VeinVenous ThrombosisVeinsSaphenous VeinVaricose VeinsFemoral VeinPulmonary VeinsJugular VeinsMesenteric VeinsRenal VeinsUmbilical VeinsIliac VeinHepatic VeinsPopliteal VeinSubclavian VeinCerebral VeinsRetinal VeinAzygos VeinBrachiocephalic VeinsAxillary VeinRetinal Vein OcclusionPhlebographyVenous InsufficiencyVena Cava, InferiorGraft Occlusion, VascularUltrasonography, Doppler, DuplexHuman Umbilical Vein Endothelial CellsVascular PatencyLegThrombophlebitisVascular Surgical ProceduresEndothelium, VascularVascular GraftingTreatment OutcomeCatheter Ablation