Inflow Improve for Deep Vein ThrombOsis with Ultrasound AcceLerated ThrombOlysis and Venoplasty

Inclusion Criteria: * Patient admitted in Vascular Surgery Unit, San Raffaele Hospital, Milan * Patients able to sign specific informed consent for the study. * Proximal deep vein Thrombosis (iliac vein, common femoral vein, deep femoral vein, and femoral vein) that was objectively diagnosed with duplex imaging and/or venography ≥ 6 months prior to study screening. * Persistent chronic deep vein Thrombosis causing restrictive flow, as confirmed by imaging, within 60 days prior to the study procedure. * Failed a minimum of 3 consecutive months of conservative treatment (therapeutic anticoagulation and compression stockings). * Villalta score ≥8 for the affected limb within 30 days prior to the study procedure Exclusion Criteria: * Treated with mechanical thrombectomy within 2 weeks of the study thrombolysis procedure. * Treated with thrombolysis drugs within 48 hours of the study thrombolytic procedure. * Life expectancy less than (\<) 1 year. * Body Mass Index (BMI) greater than (\>) 40 kilograms/square meter (kg/m\^2) or per Investigator's discretion participant is able tolerate the procedure and be compliant with post-procedure increased physical activity. * No flow in popliteal vein on duplex imaging * Thrombus extending ≥ 3 centimeters (cm) into the inferior vena cava (IVC). If central venous occlusion, consider computed tomography (CT) or magnetic resonance venography (MRV). For participants with bilateral DVT, it is recommended that central imaging be performed prior…