The investigation was designed as a multi-center, prospective, single-arm, historical (literature) controlled clinical study of VenaTech Convertible filter safety and performance in 75 subjects in whom the filter has been implanted, converted, and followed for 6-months. The study could enroll up to 323 patients to ensure 75 converted subjects with 6 months of follow-up data. Converted subjects were followed at 30-days, 3-months, and 6-months post conversion. Subjects that were unable to undergo conversion were followed at 6-months post filter implant (permanent filtration subjects).