IVC filters what you need to know

1. IVC filterswhat you need to know Sam Chakraverty Consultant Radiologist Ninewells Hospital Dundee, Scotland

2. IVC filters When rather than How

3. IVC filters • Placed to prevent significant PE from deep veins of the leg, pelvis or IVC • The best method of preventing such PE is anticoagulation

4. IVC filters • RITI module 1c_027 • Clinical Radiology (2009) 64:502-509 • 3 centre audit in UK over 12 years • BSIR IVC Registry

5. Venous thrombo-embolic disease • 30% of patients with venous TED die within 30 days • 1 in 5 die of PE • 1% hospital admissions from any cause • 1 in 5 of these have PE • Isolated calf vein thrombosis not always benign

6. Venous thrombo-embolic disease • Multiple controlled trials confirm benefit of anticoagulation • Repeated confirmation of efficacy for newer agents • The best method of preventing such PE is anticoagulation

7. Evolution • Prevention of possible embolism from deep veins to lungs • Surgical caval interruption • Surgical caval clips/plication • Insertion of filter with surgical access • Insertion of filter with percutaneous access • Possibility of retrieval • Most permanent filters retrievable

8. Indications • Absolute / “definite” • Relative • Prophylactic • Evidence base is poor

9. IVC filter – “definite” indications • Recurrent PE despite adequate therapeutic anticoagulation • DVT or PE when anticoagulation is or has become contraindicated

10. IVC filter - relative indications • Patients with PE and limited cardiorespiratory reserve • Patients with massive PE requiring thrombectomy or thrombolysis • “free-floating” iliofemoral DVT

11. IVC filter - prophylactic indications • surgery / delivery in patients with DVT or recent PE • Spinal cord trauma • High risk polytrauma

12. IVC filter - prophylactic indications • surgery / delivery in patients with DVT or recent PE • Spinal cord trauma • High risk polytrauma • Evidence base = 0

14. IVC filter use variable • USA 140 per 1 million

15. IVC filter use • USA 140 per 1 million • Sweden 3 per million • UK ?

16. IVC filter use • USA 140 per 1 million • Sweden 3 per million • UK ? ?30 per million • But increasing x3 1996-2004

17. Evidence base is poor • 1 RCT patients with DVT • Combined with trial of LMWH and iv heparin • 200 pts anticoagulation • 200 pts anticoagulation + filter • Day 12 • 2 patients had PE in filter group • 9 patients had PE in non-filter group • Odds ratio 0.22 (0.05- 0.9)

18. Evidence base is poor • 1 RCT patients with DVT • Combined with trial of LMWH and iv heparin • 200 pts anticoagulation • 200 pts anticoagulation + filter • 2 years • 37 patients had recurrent DVT in filter group • 21 patients had recurrent DVT in non-filter group • Odds ratio 1.87 (1.1-3.3)

19. Evidence base is poor • 1 RCT patients with DVT • Combined with trial of LMWH and iv heparin • 200 pts anticoagulation • 200 pts anticoagulation + filter • 2 years • 37 patients had recurrent DVT in filter group • 21 patients had recurrent DVT in non-filter group • NO difference in mortality

20. What does this tell us? • IVC filters unlikely to stop all PE when inserted in other groups of patients • Associated with some increased incidence of recurrent DVT

21. What does this not tell us? • Whether any of our definite or absolute indications for filter insertion are correct • Whether our relative indications for filter insertion are correct

22. Assumptions • IVC filters don’t stop all PE but hopefully stop large life-threatening PE • May therefore have some impact on mortality • The increased risk of recurrent DVT is acceptable Are parachutes effective? multiple single airplane studies only No RCT Unlikely to get a RCT for filter use in patients who are not anticoagulated

23. Procedure • Definite indications • Reasonable to proceed • Check patient has has the best, most cost-effective and evidence-based treatment • Relative indications • Always discuss pros and cons • No right answer • Importance of audit and registry data over time

24. Procedure • Usually aim to place below renal veins • suprarenal placement if IVC thrombus • small (6F) sheaths • local anaesthetic

25. Procedure • no sedation • no starvation • ? stay therapeutically anticoagulated • bed rest 1 hour

26. Procedure • Review imaging before you start • Where is DVT? • How big is IVC? • May give you information re IVC anatomical variation • Check you know how to deploy filter • Some easier than others to remember • Keep instructions to hand

27. Procedure • Usually R CFV or R IJV • Modern filters tolerant of other approaches • Check anatomy normal (iliac vein confluence) • Check position of renal veins

28. Procedure • Mark site below renal veins • Deploy filter • Remove sheath • Finish

29. Procedure – femoral approach

30. Procedure – jugular approach

31. Permanent or temporary? • Place a potentially-retrievable filter anyway • window for retrieval used to be 2 weeks, now longer periods possible • can remain as a permanent filter if becomes appropriate • anticoagulation if possible

32. Permanent or temporary? • Decision and timing can be left until later, but don’t lose patients • Best is as early as possible e.g. mobilizing and therapeutically anticoagulated ?? • Only 1/3 of retrievable filters end up being removed

33. Retrieval • Potentially retrievable filters not always retrievable • IVC thrombus (doing its job) • Or the cause... • technical failure 5-10% • Complication rate of removal is not zero • Do you need to retrieve it?

34. Retrieval

35. Complications • Access site thrombosis • IVC perforation • Migration • rare but catastrophic • Structural failure • IVC thrombosis • ?10-20% at 5 years • anticoagulate if possible

36. IVC filters • Discuss non-definite indications • The best method of preventing such PE is anticoagulation