The inferior vena cava (IVC) is a large vein that enters the bottom part of the heart. Venous blood from the lower portion of the body drains into the IVC. The IVC then returns blood back to the heart. An IVC filter is placed to help prevent the blood clots moving from the legs to the heart or lung. The idea behind using a filter in the IVC is to capture potential fatal pulmonary emboli at an anatomical location where they may pose less risk for the patient. Early filters, 1960's and 70's were, remained in the vein permanently. More recently, temporary or retrievable filters have been developed and are being widely used.

Complications have been demonstrated with long-term placement of IVC filters. In a randomised study it was found that that patients with IVC filter placement had greater than three times the incidence of recurrent deep vein thrombosis (DVT) compared to their control population at two years. Blockage of the vein, recurrent pulmonary emboli, filter penetration and filter fragmentation have all been described.

With the advent of retrievable filters (filters that can be place temporarily and then removed at a later date) there has been renewed popularity for placement of temporary filters. To our knowledge, no one has yet to follow the population of intended temporary IVC filters, who undergo failed retrieval, and consequently end up with a permanent IVC filter. We plan to prospectively enrol 40 Alfred patients who have undergone a temporary IVC filter placement and subsequently have had failed IVC filter retrieval. Our aim is to evaluate the long term outcomes for patients with failed IVC retrieval.

Specifically we will determine the risk, due to failed filter retrieval, of:

• IVC stenosis
• IVC occlusion
• Development of DVT and
• analyse the clinical outcomes (symptoms), their prevalence and their distribution

Patients will receive routine care and their data will be analysed annually as collected. The follow-up period is indefinite and will be at the discretion of the treating doctor.