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Though inferior vena cava (IVC) filters were designed to capture and dissipate blood clots before they can reach the lungs or the heart, they have been linked with a number of complications over the past few years. They look like little spiders, and their “legs” can break off and migrate to other areas of the body, where they can become embedded in tissues and organs. They can also tilt after implantation, puncturing the vena cava and potentially becoming a source of blood clots themselves.

Once the filters move or fracture this way, they are much more difficult to remove. Even though they are designed to be temporary, sometimes they end up embedded in the body permanently, as the risk to remove them is too great. In a 2013 study, for example, researchers noted that of 679 IVC filters, only 8.5 percent were successfully removed.

It’s not only prior to removal that these devices tend to tilt, however. Sometimes, it occurs during the retrieval process itself, making retrieval more difficult and risky. A group of New York researchers decided to look into why this might be happening. They recently presented their findings at the 2016 Society of Interventional Radiology Meeting.

Study Shows Some Filters Tilt Less Than Others

According to a “Medical Research” interview with lead researcher Eric T. Aaltonen, they decided to conduct this study after finding that Bard Denali IVC filters tended not to tilt during retrieval and were therefore easier to remove. (The FDA advised in 2014 that the devices should be removed within 29-54 days after implantation, as long as the patient’s risk of pulmonary embolism had subsided.)

They decided to compare Denali filters with ALN and Option filters, and found that the Option filters, over the other two, had an increased rate of tilt during retrieval, and increased retrieval time. They added that this tilting action required doctors to use more equipment for a successful retrieval.

The study showed that different brands of filters act differently, and the researchers recommended that patients and doctors consider the differences when discussing which to use. This was a small study, though, and they suggested that larger studies be conducted to detect other differences between various filters.

They added that in addition, “long term safety profiles of retrievable filters also need to be further evaluated, especially for relatively newer filter brands.”

Plaintiffs Claim IVC Manufacturers Were Negligent

The FDA first warned about the risks associated with IVC filters in 2010. Between 2005 and 2010, they received 921 adverse event reports involving these filters. Most reports involved device migration, while others involved detachment of components that moved to other areas of the body, perforation of the IVC and filter fracture.

Both C. R. Bard and Cook Medical, manufacturers of IVC filters, are currently defending lawsuits in consolidated litigation in Arizona and Indiana, respectively. Plaintiffs claim that the companies failed to warn of the serious risks associated with their devices, and also failed to conduct thorough clinical trials to determine the risks and make sure the products were safe before releasing them on the market.

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