The treatment protocol the study team will be following is as follows for all enrolled patients. First, a pulse spray tPA infusion with 20 cc of 8 mg tPA and saline will be administered to the thrombus with a 20-minute dwell time. Afterwards, an 8F curved sheath (Indigo 8 Torq Tip, ranges 85 to 115 cm) with CAT8 penumbra device will be used to aspirate the thrombus. If the operating physician deems necessary, they will have the option at that point to balloon plasty, stent, or use catheter-directed thrombolysis at this point. Clinical parameters such as areas of clinically-significant stenosis, extent of thrombus, (more parameters) will be tracked at the time of the procedure. The device is being used is FDA approved and being used according to FDA indications.

The treatment protocol the study team will be following is as follows. First, a pulse spray tPA infusion with 20 cc of 8 mg tPA and saline will be administered to the thrombus with a 20-minute dwell time. Afterwards, an 8F curved sheath (Indigo 8 Torq Tip, ranges 85 to 115 cm) with CAT8 penumbra device will be used to aspirate the thrombus. If the operating physician deems necessary, they will have the option at that point to balloon plasty, stent, or use catheter-directed thrombolysis at this point. Clinical parameters such as areas of clinically-significant stenosis, extent of thrombus, (more parameters) will be tracked at the time of the procedure. The device is being used is FDA approved and being used according to FDA indications.

Patient outcomes will be measured through clinical grading of PTS severity using the Villalta score, a clinical measure for the post-thrombotic syndrome that grades the severity, from 0 (absent) to 3 (severe), of each of 5 patient-rated symptoms (pain, cramps, heaviness, pruritus, and paresthesia) and 6 clinician-rated clinical signs (edema, redness, skin induration, hyperpigmentation, venous ectasia, and pain of calf). A summative score of 5 or more on the Villalta scale indicates the presence of the postthrombotic syndrome (Villalta).