IVC filters are small medical devices that are implanted in patients to prevent blood clots in the lungs. The blood clots will stay in the filter for a time until the body is able to break them down. Because the device will only prevent clots from going to the lungs or heart and will not do anything for clots in the pelvis or legs, most patients are on blood thinning drugs in addition to having the filter in place.
While these can be life-saving devices for some patients, they also have a high degree of complications and side effects. Some of the IVC filters with the most common problems include these:
- Bard G2 Filter
- Bard Recovery Filter
- Cook Celect
- Gunther Tulip Filter
FDA has gotten thousands of serious adverse event reports about IVC filters in the last decade. Many of the cases involved the arms of the filter puncturing the wall of the inferior vena cava or migrating out of position. Small pieces of the devices have been known to travel to the lungs or heart and causing a stroke or embolism.
From 2005-10, there were more than 900 serious adverse event reports received by FDA regarding IVC filters:
- 35% involved IVC Filter migration (328 reports)
- 15% involved IVC Filter embolization or detachment of device components (146 reports)
- 7.5% involved IVC Filter perforation (70 reports)
- 6% involved IVC Filter fractures (56 reports)
Some of the complications involving IVC filters are as follows:
IVC filters may migrate from the position where they were deployed to the heart or to the pulmonary outflow tract. The best treatment plan for migration of the IVC filter is to use a loop snare or another retrieval device. However, in some cases, migration to heart valves, the right ventricle of the heart or the pulmonary outflow tract, removal of the migrated IVC filter may be very difficult. Surgery could be needed.
IVC filters can reduce the chances of embolism, there is still a risk of embolisms occurring with the devices. There have been reports of an increase in the incidence of thrombosis after a filter has been inserted in patients that did not have any sign of thrombosis before insertion.
The reported rate of caval thrombosis with an IVC filter implanted varies according to the study, but it has approached 50% in some clinical studies. It seems that the risk can increase with the amount of time that the device is implanted in the body.
Eight cases of IVC filter fracture were reported in a database of IVC filter problems since the filters were first introduced years ago. The type of filter that was used in each case was not provided. There have been scattered reports of permanent filters being fractured. One report indicated that there were fractures of one strut in six out of 38 patients. However, in those cases, none of the fractures involved the basket part of the filter.
Penetration of the vein wall by the device is quite common but often is clinically not significant. The incidence of this occurrence has been found to be as common as 40% to 95%. Other related problems have been reported, such as:
- Aortic penetration
- Ureteral perforation
- Duodenal penetration
Laceration of lumbar vessels that caused major bleeding also has been reported in a few cases. Further, IVC erosion that led to complete filter perforation that caused deaths in some cases has been reported, as well.
Note that retrieving temporary filters can carry a risk of perforation or rupture of the device. This is a particular risk after the implant has been in the body for an extended time period.
A study from MA General Hospital found incidence of pulmonary embolism after implantation to be 5.6%. Incidence of fatal embolism was 3.7%. Other studies have reported less than 5% rate of pulmonary embolism.
Bacteremia is present in some patients who have IVC filters implanted. Doctors avoid access sites that are infected, and will use retrievable filters in patients with bacteremia, so that the device can be removed just in case there is a problem with bacterial infection.
Device Retrieval Problems
There are no long term studies yet related to results with removing retrievable filters. While there are major advantages to an IVC filter that can be removed, complications that could occur include large clot burden, wall apposition that prevents removal, and difficulty with retrieval, which can require a procedure that takes much longer.
It should be noted that IVC filters are not benign devices, and should only be in patients that have a high risk of pulmonary embolism or deep venous thrombosis. Evidence has increased over time that the rate of complication could be higher than previously thought.
Risks of problems go up considerably the longer the devices are left in place. Retrievable IVC filters should be taken out of the body as soon as possible. In most patients, this may be two or three weeks after anticoagulation has started.
However, the majority of retrievable filters are left in for far longer than is medically necessary. This often is the case because there is a large clot stuck in the filter, an inability to get the filter out due to in growth or tilt, and also loss of follow up with the patient.
Also, research indicates that some doctors will place a retrievable IVC without a specific plan to remove it. Many experts stress that it is very important that the removal of the temporary IVC filter be attempted in a timely manner. Patients that stand to gain the most from preventing an embolism stand to lose a great deal if they have a retrievable IVC filter left in for too long, as it can lead to serious complications. For example, young patients who have a retrievable filter left in place for too long are at risk for filter fracture, perforation, embolization and caval thrombosis.
It should be noted that some of the other complications that can occur with this filter are:
- Cardiac tamponade, where the fluid around the heart can inhibit the heart beat
- Obstruction or narrowing of the inferior vena cava, which can reduce blood flow in the heart
- Edema, or swelling in the legs
- Chest pain
- Hemorrhage or internal bleeding
- Breathing difficulties
- Death in rare cases