60 y/o male who presented to the IR clinic for consultation | Figure 1

SIRRFS

Radiology

60 y/o male who presented to the IR clinic for consultation of bilateral lower extremity venous insufficiency and recent history of a ruptured venous ulcer for which he was interested in endovenous laser treatment. During the clinic visit, he reported that he had previously had an IVC filter placed in 2008 after sustaining a T11 burst fracture. He also reported that he had a previous imaging evaluation which demonstrated IVC occlusion at the filter site in 2012. The patient notes significant bilateral lower extremity edema requiring the constant use of compression socks.

Q1: Inferior vena cava thrombosis can result in which of the following?

a. Asymptomatic

b. Deep venous thrombosis of the lower extremities

c. Chronic venous insufficiency

d. Post-thrombotic syndrome (lower extremity swelling, pain, and skin changes)

e. Limb ischemia

f. All of the above

Q2: What is the estimated average retrieval rate of IVC filters nation-wide?

a. 95%

b. 75%

c. 50%

d. 30%

e. 10%

Figures 1 & 2: Duplex sonography of the bilateral lower extremities was performed
Figures 3 & 4: Infrarenal IVC with OptEase filter
Figure 5: Multiple abdominal wall and groin varices

The decision was made to perform iliocaval venography and attempt retrieval of his OptEase IVC filter. His IVC and bilateral common iliac veins would then be reconstructed using self expanding stents.

Background

Blood clots in the lungs are called pulmonary emboli. They commonly originate in the leg or pelvic veins, where they can fragment and travel to the lungs via the inferior vena cava (IVC, large vein which carries blood from the lower body to the heart). Further emboli are usually prevented by blood thinning medications (anticoagulants). In some instances (approximately 4% of cases), anticoagulation fails, or it is too dangerous to give anticoagulation.

Vena caval filters are metal alloy devices inserted within the IVC to trap blood clots. Modern filters are 'retrievable,' allowing their removal once they are no longer required. However, a number of retrievable filters are not removed. The long‐term safety profile of these devices is not known. The aim of this review was to assess the effectiveness and safety of vena caval filters. The review authors looked for studies comparing filters with no filter, and studies comparing different filter designs.

Study characteristics and key results

We included six trials with a total of 1388 participants in the review (current until 10 September 2019). There were too many differences between these studies so we could not combine the results.

Two trials were applicable in current clinical settings. One trial showed there is no clear benefit in receiving a retrievable filter for the first three months after an acute PE, for those who can receive anticoagulation, in terms of recurrent pulmonary embolism (PE), deep vein thrombosis (DVT), death or bleeding. Not all filters could be removed. Only minor complications from the filters were noted at six months.

Another study of people who had sustained multiple traumatic injuries did not show any benefit of inserting a filter three days after injury to prevent PE, or reduce deaths. Preventive anticoagulation and calf compression devices were administered to participants when possible.

We are unable to draw any conclusions from the remaining four included studies. This is because three studies are no longer clinically relevant because they utilised permanent filters which are seldom used now, or they did not use routine preventative anticoagulation which is current standard practice. One study showed an increased rate of lower‐extremity DVT in the permanent filter group. The fourth study compared two filter types and was stopped prematurely and thus did not generate sufficient data.

Reliability of the evidence

Two studies were relevant in current clinical contexts. The evidence presented by both of these studies is of moderate certainty. We reached this assessment because we were not able to combine the data from the studies, and because of the low numbers of participants and events involved. The studies differed in type of participants and clinical situations. There is a further need for trials evaluating the effectiveness of caval filters in people who cannot receive anticoagulation, or when PE occurs despite adequate anticoagulation.