IVC Filters - Who and When

Duncan F Ettles MD, FRCP, FRCR Consultant Cardiovascular and Interventional Radiologist

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The morbidity and mortality due to pulmonary embolic disease is very difficult to establish. Embolic disease is still under-diagnosed and often considered only after other investigations have proved inconclusive. Estimates of mortality suggest a figure of up to 35% in the 12 months in following untreated pulmonary emboli. A growing body of evidence shows that caval filtration reduces the incidence of early fatal repeat emboli, but controversy remains over long term outcomes (1,2). IVC filters have very low long term morbidity, despite fears of potential device related complications (3,4).

The commonest indications for filter placement are proven pulmonary emboli in patients with contraindications to anticoagulation therapy, and in patients with repeated pulmonary embolism despite effective anticoagulation. Increased use of caval filters has led to an expanded range of indications including prophylaxis after pelvic trauma, prior to abdominal surgery and in patients with documented iliocaval thrombus (5,6,7)

A range of devices is commercially available, manufactured from stainless steel or nitinol compounds and all can be delivered percutaneously, using either transfemoral or transjugular approaches. One device, the Simon nitinol filter, can be placed from the antecubital fossa , which can be very useful in the dyspnoeic patient who is unable to lie flat during filter insertion. There is no data to establish the superiority of any of the currently available filters as few comparative studies exist (8). Caval filters may be permanent (ie Bird’s Nest) or retrievable (Gunther Tulip) in type. Retrievable or temporary filters are particularly suitable in younger patients requiring short term prophylaxis. These filters can be removed up to several weeks or longer after implantation or alternatively, repositioned within the IVC at suitable intervals to avoid incorporation into the wall of the cava (9). In our unit and elsewhere, temporary filters have been used for prophylaxis in the late stages of pregnancy and successfully removed after delivery (10).

Filter placement is rarely problematic, with cannulation of a suitable access vein followed by preliminary venography to demonstrate venous anatomy. Once the level of the renal veins and position of the iliac confluence is established, the filter is deployed in the infrarenal portion of the IVC. When preliminary imaging shows extensive caval thrombus, a jugular approach is preferred. Occasionally, suprarenal filter placement is indicated which can be technically difficult if the intrahepatic portion of the IVC is short (11). In the management of subacute massive pulmonary embolism, IVC filter placement can be combined with pulmonary angiography and mechanical clot disruption or intrapulmonary thrombolysis. Device related complications are rare, but strut fracture and occasionally fatal migration have been reported (4,12). Modern designs are much less prone to migration but some authorities recommend surveillance by plain abdominal radiography. Perforation of the IVC wall is well recognised but usually clinically unimportant (13). Occlusion of the IVC following filter insertion has been reported and may relate to filter type. In the author’s unit we found a less than 5% incidence using the Bird’s Nest filter (3,4,14) . Recurrent pulmonary emboli occur with an incidence of between 2 and 5% after filter implantation. This may be due to failure of thrombus trapping, collateral venous pathways or thrombus propagation on the superior aspect of the filter (1,15). Unless contraindicated, anticoagulation should be continued for at least 6 months after filter insertion to minimise the risks of recurrent emboli and DVT.

Retrievable filters are removed using a jugular approach and a specially adapted snare set. Check venography is performed to ensure that no trapped thrombi are present.

If this is shown to be the case, then the filter is left in situ and regarded as a permanent device. Even after short implantation periods, some temporary filters become incorporated into the cava and in these circumstances, forcible removal should not be attempted (16). Maldeployment of temporary devices or subsequent tilting within the cava may also make retrieval impractical in a small number of cases.

Since their first reported use in 1967, many thousands of caval filters have been implanted with encouraging results from numerous case series (17). However, a lack of randomised data concerning long term outcomes after implantation means that further prospective evaluation is still required.

References

1) Decousus H, Leizorovicz A, Parent F, et al. A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep vein thrombosis. New England Journal of Medicine 1998; 338(7): 409-415.

2) Girard P, Stern J, Parent F. Medical literature and vena cava filters. So far so weak. Chest 2002; 122: 963-7

3) Nicholson A, Ettles DF, Paddon AJ, Dyet JF. Long term follow-up of the Bird’s Nest IVC Filter. Clinical Radiology 1999;54: 759-764

4) Ray CE, Kaufman JA. Complications of inferior vena cava filters. Abdom Imaging 1996;21:368-374

5) Pacouret G, Alison D, Pottier JM, Bertrand P, Charbonnier B. Free-floating thrombus and embolic risk in patients with angiographically confirmed proximal deep venous thrombosis. Arch Int Med 1997;157:305-308

6) Proctor MC. Indications for filter placement. Semin Vasc Surg 2000;13:194-198

7) Rogers FB, Strindberg G, Shackford SR, et al. Five year follow-up of prophylactic vena cava filters in high-risk trauma patients. Arch Surg 1998;133:406-412

8) Millward SF. Vena cava filters: continuing the search for an ideal device. J Vasc Interven Radiol 2005;16:1423-1425

9) Terhaar OA, Lyon SM, Given MF, et al. Extended interval for retieval of Gunther Tulip filters. J Vasc Interv Radiol 2004;15:1257-1262

10) Kawamata K, Chiba Y, Tanaka R, Higashi M, Kazuhiro N. Experience of temporary inferior vena cava filters inserted in the perinatal period tp prevent pulmonary embolism in pregnant women with deep vein thrombosis. J Vasc Surg 2005;41:652-656

11) Matchett WJ, Jones MP, McFarland DR, Ferris EJ. Suprarenal vena caval filter placement: follow-up of four filter types in 22 patients. J Vasc Interv Radiol 1998;9:588-593

12) Riley P, Mackie G, Taylor S. Migration of an Antheor vena cava filter into the right pulmonary artery. J Intervent Radiol 1997;12:99-101

13) Lok SY, Adkins J, Asch M. Caval perforation by a Greenfield filter resulting in small bowel volvulus. J Vasc Interven Radiol 1996;7:95-97

14) Ballew KA, Philbrick JT, Becker DM. Vena cava filter devices. Clin Chest Mede 1995;16:295-305

15) David W, Gross WS, Colaiuta E, Gonda R, Osher D, Lanuti S. Pulmonary embolus after vena cava filter placement. Am Surg 1999 ;65 : 341-346

16) Burbridge BE, Walker DR, Millward SF. Incorportation of the Gunther temporary inferior vena cava filter into the caval wall. J Vasc Interven Radiol 1996;7:289-290

17) Mobin-Uddin K, Smith PE, Martines LO, Lombardo CR, Jude JR. A vena cava filter for the prevention of pulmonary embolus. Surg Forum 1967;18:209-211