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Retrievable inferior vena cava (IVC) filters are porous barriers. They are implanted inside the main vessel, the inferior vena cava (IVC), through which blood from the lower extremities and pelvis is carried back to the heart. 1 This is normally done on an outpatient basis.
IVC filters are typically implanted in patients who are at risk of blood clots in the lungs, known as pulmonary emboli (PE), when anticoagulant medications cannot be used or have not been effective. 2
Function of Inferior Vena Cava Filters
The purpose of IVC filters is to prevent blood clots that have formed in the lower extremities or pelvis from entering the lungs or heart. If blood clots do enter the heart or lungs, they could cause potentially serious or fatal harm.
Retrievable IVC filters are approved by the U.S. Food and Drug Administration (FDA) to be implanted either temporarily or permanently. 3
Doctors may consider implanting a retrievable IVC filter when a patient has recurrent pulmonary embolism. Use of the devices for preventing recurrent PE is approved by the FDA in these situations: 4
- Anticoagulant therapy has failed.
- Anticoagulant therapy is contraindicated.
- Emergency intervention is required after a massive pulmonary embolism when anticipated benefit of conventional therapies is reduced.
Preventing Pulmonary Embolisms
The respiratory system, working with the circulatory system, allows oxygenated blood to circulate throughout the entire body. For most people, these systems function without impairment.
Some retrievable IVC filters have demonstrated patterns of failure, with some studies reporting many problems.
For some, however, there may be certain diseases present or a tendency that causes the body to form tiny clots of blood that can inhibit blood moving through the body efficiently. The clots are called thrombi.
These clots often originate in the deep veins of the legs. The causes vary, but when these thrombi form in the legs it is an event referred to as deep vein thrombosis, or DVT.
These DVT clots can migrate into the main portion of the inferior vena cava, which can transport them to the upper body and into lungs or heart. If the clots enter the lungs and block the passage of blood in the vessels in this organ they are known as pulmonary emboli — PE for short. PE carry the potential for serious injury or death because of the vital function the lungs play in providing the body with oxygenated blood.
A retrievable IVC filter works much like the screen inside the end of a kitchen faucet. The screen prevents mineral deposits contained in the water supply from passing through the faucet.
Retrievable IVC filters are intended to intercept migrating DVT before they reach the lungs. The blood that passes beyond the point of the retrievable IVC filter is “strained” of clots, but the retrievable IVC filter can be removed once the risk of PE has passed.