An IVC filter is a small, metal device designed to stop a blood clot from traveling to the lungs and causing a pulmonary embolism, or a blockage in one of the pulmonary arteries. Doctors insert the device into a patient’s inferior vena cava, the main vein that returns blood from the lower body back to the heart. The device resembles a metal cage, and when blood clots form in the legs, known as deep vein thrombosis, the filters catch the clots. IVC filters are commonly placed in people who are at risk for pulmonary embolism when anticoagulants (blood thinners) are ineffective or not an option. The filters are designed to be permanent implants but some can be removed.
The U.S. Food and Drug Administration (FDA) approved the device in 1979, and its use has increased continuously through the years. By 2012, doctors inserted about 259,000 filters in patients. A 2016 analysis published by the American College of Cardiology found IVC filters are likely being over-used. The author concluded that “retrieval rates are low and information regarding appropriate use and surveillance are lacking.”
According to the agency, “The FDA is concerned that retrievable IVC filters, when placed for a short-term risk of pulmonary embolism, are not always removed once the risk subsides.”
In 2010 and again in 2014, the FDA released safety communications in which the agency warned of adverse events and product problems associated with IVC filters, including device migration, filter fracture, embolization (movement of the entire filter or fracture fragments to the heart or lungs), perforation of the IVC, difficulty removing the device, lower limb deep vein thrombosis and IVC occlusion.
The agency recommends doctors consider removing retrievable IVC filters as soon as protection from pulmonary embolism is no longer needed. “For patients with retrievable filters, some complications may be avoided if the filter can be removed once the risk of pulmonary embolism has subsided,” the agency said. The FDA recommends retrievable devices be removed between the 29th and 54th days after implantation in patients in which the risk of pulmonary embolism subsided.
How IVC Filters Work
The inferior vena cava is the largest vein in the body. It moves de-oxygenated blood from the lower legs to the heart and then to the lungs. Doctors implant an IVC filter in the vein to prevent blood clots from traveling through the vein into the lungs.
Using a catheter, or a thin tube, a doctor inserts the device into a patient’s inferior vena cava through a small incision in the neck or groin. The device’s metal wires capture and trap blood clots before they can reach the lungs.
Some filters are permanent, and some are retrievable or temporary. Doctors remove retrievable filters in a similar way that they implant them. Health care providers inject contrast or X-ray dye around the device to make sure it is safe to proceed with the removal. A catheter-like snare goes into the vein and grabs the hook located at the end of the filter. A sheath covers the filter, and the doctor pulls the device out of the vein.
Types of IVC Filters
The two major companies that manufacture IVC filters are C.R. Bard and Cook Medical.
The most popular brands of IVC filters include:
- The Bard G2 Express filter
- The Bard G2 filter
- The Bard Recovery filter
- The Cook Celect filter
- The Cook Gunther Tulip filter
- The Boston Scientific Greenfield filter
There are two types of IVC filters: permanent and optional (retrievable). Retrievable filters are intended for short-term use but provide the option either for long-term use or for removal when there is no longer a risk for pulmonary embolism. Permanent IVC filters, on the other hand, are designed only for long-term use.
According to a 2014 study published in the Journal of Vascular Surgery, retrievable IVC filters that were left in place were associated with significantly higher complication rates than permanent filters. The study’s authors identified 383 patients in whom retrievable filters were left in place and compared them with patients with permanent filters. Both thrombotic (blood clot-related) and device-related complications were more common with retrievable filters.
When Doctors Recommend IVC Filters
Blood clots that develop deep inside the pelvis and the lower and upper extremities are referred to as deep vein thrombosis, or DVTs. DVTs are not typically life-threatening, but they can cause death when they travel to the lungs and produce pulmonary embolisms, or clots that block normal blood flow in the lungs. These embolisms cause about 300,000 deaths every year. It is the third-most-common cause of death in hospital patients.
People who had recurrent DVTs while on anticoagulation (blood-thinning) medication and/or people who can’t tolerate or consume anticoagulation because of an adverse reaction or bleeding make good candidates for IVC filters. Doctors may also recommend IVC filters in patients who suffer serious trauma or undergo surgery because the risk of blood clots is elevated.
Cases in which doctors may recommend using an IVC filter:
- Car accidents
- Voluntary or emergency surgeries
- Gunshot or stabbing injuries
- Dialysis treatment
- Patients who are immobile
- Patients who just had a baby
- Spinal cord injury
- Cancer diagnosis or treatment
- Serious falls
IVC filters have the potential to migrate away from their surgically positioned location, rendering them ineffective. Sometimes the device itself punctures a vein, causing bleeding and other complications. Broken pieces of filters can travel through the blood and lodge in other organs, such as the heart. Retrievable filters in particular are associated with potential risks, like damaging veins and failing to stop blood clots from bypassing the device.
IVC filter complications typically fall into three categories: procedural, delayed and retrieval.
Procedural complications occur when doctors insert the filter, these include:
- Access site bleeding and/or bruising
- Blood vessel puncture
- Incorrect placement and/or malposition of filter
- Defective filter deployment
Retrieval complications occur when doctors remove the filter and include:
- Blood vessel perforation
- Large clots in the filter that prevent removal
- Difficult retrieval causing long surgery times
- Scars in the vein that prevent removal
Delayed complications occur after the filter is in the body and include:
- Migration to another part of the vena cava, the heart or other organs
- Deep vein thrombosis (blood clots in the legs)
- Filter fracture or breakage
- Perforated organs
- Device infection
- Blockage that causes swelling in the legs
- Embolization (detachment of device components)
FDA Reports and Actions
Between 2005 and 2010, the FDA received 921 device adverse event reports involving IVC filters. About 328 reports involved device migration, 146 involved embolizations, 70 involved perforation of the IVC, and 56 involved filter fracture. Some of the reported events resulted in adverse clinical outcomes in patients. The agency concluded the adverse events could have been related to a retrievable filter remaining in the body after the risk for pulmonary embolism had subsided. It recommended removing retrievable devices within 54 days after implantation if the risk has diminished.
The FDA has also required the collection of additional clinical data for currently marketed IVC filters in the U.S. The studies address safety questions that remain unanswered for both permanent and retrievable filters, according to the agency. Manufacturers were given two options for collecting the data: the PRESERVE study or postmarket surveillance. PERSERVE stands for PREdicting the Safety and Effectiveness of InferioR VEna Cava Filters and is an independent national clinical study that will examine the use of IVC filters in the prevention of pulmonary embolism. Postmarket surveillance will involve 522 studies.
“The data gathered from the PRESERVE study and the 522 studies will help the FDA, manufacturers and health care professionals assess the use and safety profile of these devices, understand evolving patterns of clinical use of IVC filters and ultimately improve patients care,” according to the FDA.
IVC Filter Recalls
In 2005, the FDA announced a Class 2 device recall of the Greenfield Vena Cava Filter manufactured by Boston Scientific. The manufacturer cited the lack of a taper on the braided sheath of the delivery system as reason for the recall. Boston Scientific sent an “Urgent Recall Notice” to customers instructing them to immediately discontinue use of and isolate the recalled lots. “The lack of a taper could lead to vessel damage as a result of the sheath catching on the edge of the vein and causing a tear,” according to the recall notice. A Class 2 recall is used for a situation in which use of a product may cause temporary or medically reversible adverse health consequences or where the probability of serious adverse health consequences is remote. The recall was terminated in November 2006.
Then in 2013, the FDA announced a recall of a retrievable IVC filter manufactured by Cordis Corporation, citing a labeling correction. Cordis sent an “URGENT Medical Device Correction” letter to customers in the U.S. and Canada. The recall covered about 33,000 units of the device distributed in the U.S. between May 6, 2010, and April 2, 2013. The labeling correction was “to provide clarification and additional information to minimize likelihood of implanting the filter backwards,” according to the FDA.
C.R. Bard Warning Letter
In 2015, the FDA sent a warning letter to C.R. Bard Inc. to notify the company of violation found at two of its facilities in New York and Arizona. The agency conducted an inspection of the C.R. Bard facility located at 289 Bay Rd, Queensbury, NY, from Oct. 6, 2014, through Nov. 25, 2014, and of the Bard Peripheral Vascular facility located at 1625 W. 3rd St., Tempe, AZ, from November 18, 2014, through January 05, 2015. According to the letter, the agency concluded C.R. Bard was manufacturing the Recovery Cone Removal System, Model RC-15 without marketing clearance or approval. The device is intended to remove IVC filters.
IVC Filter Studies
Research studies have confirmed problems with retrievable IVC filters. A 2013 study in the Journal of the American Medical Association (JAMA) looked at the filter’s failure rate. Researchers discovered doctors only removed 58 out of 679 retrievable IVC filters. When the filters remained in patients longer than medically necessary, 18.3 percent of attempts to remove the filters failed, 7.8 percent of patients had venous thrombotic events and 25 patients suffered pulmonary embolisms.
Filter Failure Rates
The FDA received 300 reports of adverse events linked to the Recovery filter.
The Recovery filter was C. R. Bard’s first-generation product introduced in 2003. A second-generation device, the Bard G2, arrived in 2005 as a replacement for the Recovery. But before Bard replaced the Recovery, the FDA received 300 reports of adverse events linked to the device. Results from one study showed about 25 percent of the Recovery filters failed, causing the device to fracture or break apart. One patient died at home, although the study did not explain the reason. An NBC News investigation linked the device to at least 27 deaths.
The Bard G2 had a 12 percent failure rate and remained on the market a shorter amount of time than its predecessor. Bard stopped selling the Recovery when the G2 arrived on the market in 2005. The G2’s successor, the G2 Express, entered the market in 2008. One study found all of Bard’s devices experienced a combined 12 percent fracture rate.
Another study found both of Cook Medical’s filters, the Gunther Tulip and the Celect, had histories of perforating patients’ vena cava wall. The perforation often occurred within 71 days of implantation, and the filters migrated out of place in 40 percent of patients.
Additional Treatment Options
IVC Filters should only be used in patients with acute blood clots who can’t take anticoagulants (blood thinners). If these filters are implanted for other indications it should be after much consideration and accompanied by appropriate documentation, experts say. For patients who are not good candidates for IVC filters, doctors may instead recommend blood thinners or lifestyle changes.
The most widely used blood thinner is warfarin, followed by novel oral anticoagulants like Xarelto, Pradaxa and Eliquis. Blood thinners carry risks for side effects like uncontrollable bleeding, and in most cases, patients who begin blood thinners must take them for the rest of their lives.
Changes in lifestyle may also prevent a person’s likelihood of developing blood clots. People should avoid smoking, high-sodium diets and things that cause high amounts of stress. Treating conditions like high blood pressure, high cholesterol or an overactive thyroid can also decrease blood clot risks.