Researchers at the UC Davis Health System have found that inferior vena cava filters (IVC filters) may increase the risk of new blood clots. The findings were published in Circulation, an online journal sponsored by the American Heart Association. The study was conducted mainly to distinguish what kinds of patients should receive an IVC filter and which should not.
The IVC filter is a cage-like device that is inserted into the vena cava, the largest vein in the body. It is used most often in patients that cannot tolerate blood thinning medication. The fingers of the cage are intended to catch blood clots, preventing pulmonary embolism.
The retrievable models such as the Recovery made by C.R. Bard are intended to be left in the patient for only a short amount of time. But when physicians are unable to retrieve the filter due to various issues such as migration, tilting or perforation, the device may be left in the body longer than recommended. This increases the risk of device fracture, which can cause the broken fingers to travel through the body and puncture vital organs as well as veins.
Lawsuits alleging injuries and deaths linked to the medical devices have been filed against makers of IVC filters such as C.R. Bard, Boston Scientific Corp. and Cook Medical. Complaints allege the Bard Recovery filter has been linked to at least 27 deaths by itself.
According to Richard White, the lead author of the study and chief of general medicine for UC Davis Health System, there have not been enough clinical trials to help doctors make the decision about whether or not to use an IVC filter for their patients.
“Decisions about the use of IVC filters have so far not been driven by good science, primarily because there have been only two very small clinical trials that studied them,” White, who is also the medical director of the anticoagulation service at UC Davis, said. “Our results will help physicians know when a filter may be helpful and when it should not be considered.”
Initial findings indicated that the filters increased the risk of leg blood clots by 135 percent, and that using an IVC filter may not benefit patients who can tolerate anticoagulation treatment.
“If a filter is used, I recommend removing it as soon as possible to help reduce the possibility of additional clots forming,” White said.