Evaluation of the Zilver® Vena™ Venous Stent

Inclusion Criteria: * Symptomatic venous outflow obstruction in up to two iliofemoral venous segments (one in each limb), demonstrated by: * CEAP 'C' ≥ 3, or * VCSS pain score ≥ 2 Exclusion Criteria: * \< 18 years of age * Pregnant or planning to become pregnant in the next 12 months * Planned surgical or interventional procedures (except thrombolysis and thrombectomy in preparation for the procedure or vena cava filter placement prior to stent implantation in patients at high risk for pulmonary embolism) within 30 days prior to or after the study procedure. * Lesions with intended treatment lengths extending into the inferior vena cava or below the level of the lesser trochanter * Previous stenting of the target vessel * Iliofemoral venous segment unsuitable for treatment with available sizes of study devices