High Rate of Fracture and Embolization
Since 2003, when temporary IVC (inferior vena cava) filters were approved by the U.S. Food and Drug Administration (FDA), they have been widely used.
An IVC filter is placed in the major vein of the body in hopes of preventing blood clots from reaching the heart or lungs where they can be fatal.
Heralded at first as a vast improvement over anticoagulant therapy, there were problems noted soon after IVC filters were approved, namely migration, vein-organ perforation, embolization and filter fracture.
Embolization is reported to be a rare complication of a strut fracture, a fracture of the long dangling spider-like legs of the IVC filter. Strut fractures occur in fewer than 5 percent of cases, according to the literature.
The Department of Cardiology at York Hospital in York, Pennsylvania, set out to determine the rates of fracture and embolization. They chose two C.R. Bard IVC filters – the Bard Recovery and the G2.
Approved by the FDA in 2003, Recovery was off the market just two years later and replaced with the Bard G2. Researchers chose to focus on those devices because they have a high prevalence of fracture and embolization. That is described basically as breaking and detaching leaving particles around a blood vessel that can lodge there and cause an embolism or blood clot.
Ironically, that is the very thing a patient is having an IVC filter to avoid.
In a retrospective patient study conducted from 2004 through 2009, 80 patients who had an IVC filter in place had fragmentation and embolization. It was present in 25 percent of patients who were implanted with the Bard Recovery and in 12 percent of those who received the newer G2.
The emboli or fragment lodged in the right ventricle in five of the seven patients receiving the Recovery IVC filter.
Extrapolating the findings, researchers warned there may be as many as 7,000 Americans who have a fractured G2 that has the potential to embolize and the high rate of fractured IVC filters could pose a public health risk.
The other problems among the implanted group were fractures seen in 16 percent of patients three years after an IVC implant. These filter fragments, made of the metal nitinol, were supposed to be an improvement over Recovery and better resist fracturing. Among these patients the fragments eventually made it to an organ.
One woman suddenly died at home, two of the patients had chest pain another needed emergency open-heart surgery to remove the fragment. The G2 filter fragments ended up in a patient’s hepatic vein (blood vessels that transport deoxygenated blood from the liver to the inferior vena cava) and in a lung. In four cases, the fractured fragments remained near the device. The changes may have made fracture less likely but they still have a potential to move, warned researchers.
This study was published in the Archives of Internal Medicine the same day the FDA warned not to leave in retrievable filters.
In 2010, the FDA issued a Safety Alert warning patients and doctors that retrievable IVC filters should not remain behind in a body after 54 days and should be removed as early as 29 days after implantation because the risks increase over time.
And to echo the concerns of the FDA, of the 189 of the patients who had been treated at York Hospital, only ten patients had the IVC filter removed. Often patients do not return for follow-up treatment if they are feeling well and have no symptoms.
Unfortunately, a published study in the Journal of the American Medical Association (JAMA) in 2013, found in one patient group, only 58 of 679 retrievable filters had been removed.
According to the American Association for the Surgery of Trauma, a multicenter trial in 21 centers found 79 percent of the IVC filters placed were retrievable, but only 22 percent were retrieved and only half of patients had followed-up after they were discharged.
The danger of metal fatigue of nitinol only increases the longer it is allowed to stay in the body. The difficulty of removing the IVC filter may increase with the passage of time.
The FDA says embolization is the second most frequent complication of an IVC filter outside of migration.
If you have one of these IVC filters you are encouraged to, at the very least, have it monitored with a CT scan to make sure it is in place. If it is a retrievable filter, talk to your doctor about having it removed.
As many as 250,000 patients a year may have had IVC filters implanted in recent years.