An IVC filter may be discussed if you have a deep venous thrombosis (DVT) in the leg. The primary concern for DVT is the risk of pulmonary embolus (PE), a clot traveling from the leg to the heart and lungs. In many cases, PE can be fatal. The standard of care for the treatment of DVT is anticoagulation with warfarin, but if you cannot take blood thinners because of bleeding problems, recent surgery or head trauma, or if you have a new or worsening clot while on blood thinners, your physician may advise placement of an IVC filter.
The vena cava is the large central vein that takes blood back to your heart. It is formed by the confluence of the right and left iliac veins, which run through the pelvis from the groin to the level of the umbilicus. An IVC filter acts as a trap or sieve to capture a blood clot that wants to travel from the legs to the heart. It looks like the wire frame of a tiny umbrella. Placement of the IVC filter is a minimally invasive procedure which generally takes less than 30 minutes and is done through a needle-stick incision. The vein at the base of your neck or in your groin is accessed with a needle, and then a sheath (tube) is guided over a wire into the vena cava. The filter is collapsed into the sheath, guided into position under continuous x-ray (fluoroscopy), and then deployed. You cannot feel the IVC filter in your abdomen and it will not cause the scanners in the airport to ring. Almost all IVC filters are nonferromagnetic, and are safe for MRI. As with any implant, it is important that you carry a card with you that identifies the type of filter you have, its location, and when it was put in.
Most IVC filters are temporary, meaning they can potentially be removed if no longer needed. For instance, sometimes a filter is placed just prior to a DVT thrombolysis procedure, and it is no longer needed after the clot is removed. Removing an IVC filter involves introducing a needle into the vein at the base of your neck, and, through this vein, guiding a wire and sheath into the vena cava. Through the sheath, a tiny lasso called a snare is advanced into the vena cava and used to capture a small hook at the top end of the filter. The filter is then collapsed into the sheath and removed. This can be done as an outpatient procedure under a light sedative. The procedure can take 10-30 minutes. Nationwide, surgeons only retrieve 50-75 percent of all temporary filters that are put in. Sometimes the filter is filled with clot, sometimes it is slightly tilted and the top hook is not exposed, or sometimes it is too embedded in the surrounding tissues to be removed safely. Our chances of removing the filter are greater the shorter the time that the filter has been in place. After a filter has been in place three months, our chances of removing it decrease significantly. Leaving a filter in and not being on blood thinners is associated with a small risk of development of clot in the filter which can lead to bilateral leg swelling.