Types of IVC Filters

Retrievable or optional IVC filters are sometimes referred to as temporary filters, even though they are FDA cleared for permanent placement. Though there is one IVC filter that is specifically designed to be implanted only on a temporary basis and cannot be used permanently. It is the B. Braun Tempofilter™ II. According to the manufacturer, this device is designed to provide effective filtration for up to three months. The Tempofilter™ II is the successor to the Tempofilter™ I. After several instances of filter migration to the right atrium (which was fatal in two cases), the development of the Tempofilter™ I was suspended. The stability of the filter has been improved in the Tempofilter™ II, but complications have been reported, including the fracture of a filter leg. Fortunately the leg was embedded in the inferior vena cava wall and did not migrate.

FDA Approved Uses for IVC Filters

All types of IVC filters are cleared by the Food and Drug Administration as a treatment for recurrent pulmonary embolism under the following conditions:

• When the patient’s condition is such that treatment with anticoagulants would cause harm.
• When anticoagulant therapy has been unsuccessful.
• Emergency treatment following massive pulmonary embolism when the benefits of conventional therapy are reduced.
• Chronic, recurrent pulmonary embolism when anticoagulant therapy has failed or is could be harmful.

*See our IVC Filter Lawsuit page for a detailed explanation of this condition.

Use of these devices as a preventative measure in patients without a history of pulmonary embolism or where anticoagulant therapy can be used successfully, does not currently have FDA approval. Such use is considered an “off-label use” of the filters. The term off-label is most often applied to medications, but may also apply to use of a medical device under conditions other than those for which the device has received FDA clearance.

Off-label use of IVC filters is common and is believed to represent more than half of all filters implanted in the United States. However, such use may be problematic. In 2014, the FDA warned that filter complications may be related to how long a filter has been implanted. The agency cited a study by researchers at the FDA’s Center for Devices and Radiological Health. The researchers reviewed the implantation of filters in patients who had a “transient, reversible risk of PE [pulmonary embolism].” They found that in these patients, once the risk of PE has passed, the risk of leaving the device in place (within one to two months) begins to outweigh the possible benefits of leaving it in place.

“…if the patient’s transient risk for PE has passed, the risk-benefit profile begins to favor [IVC filter] removal between 1 and 2 months.” Study by researchers with the U.S. Food and Drug Administration’s Center for Devices and Radiological Health (2014). The study is available on the FDA website.

Differences in IVC Filters

Inferior vena cava filters vary both in the size of the veins in which they can be implanted and in the materials of which they are made.

Vena Cava Diameter

One of the main IVC filter differences is related to the diameter of the vena cava for which they can be used. The Bird’s Nest^® Vena Cava filter, for example, can be used in a vena cava measuring up to 40 millimeters (mm) in diameter.Bard’s Denali filter is approved for inferior vena cava diameters less than or equal to 28 mm. The Cook Celect filter is designed for use in vena cavas with diameters less than 30 mm and more than 15 mm.

Materials

Most types of IVC filters are made of nonferromagnetic materials and are not affected by magnetic fields. This is important since it permits the use of magnetic resonance imaging (MRI) in patients who have been implanted with such filters.

Some types of IVC filters, however, are made of weakly ferromagnetic materials. These filters are classified as MR Conditional. MRI can generally be used with these IVC filters, but there are some restrictions. In some cases the use of MRI must be delayed to allow for the filter to become firmly attached to the vena cava wall so that it won’t move if exposed to the magnetic field. This is the case with the Cook Bird’s Nest filter. The Denali and Günther Tulip are also MR Conditional, but patients with these filters can be scanned immediately after filter placement if certain conditions are met.

IVC Filter Complications

In general, IVC filter complications appear to be much more common with retrievable filters than with permanent filters. Doctors at Chicago’s NorthShore University HealthSystem recently reviewed IVC filter placement in 1,225 patients who had received either permanent (785) or retrievable (449) filters. Retrievable filters used in this study were primarily the Cook Celect (241 patients), Cook Günther Tulip (54 patients), Bard G2X (84 patients) and Bard Recovery (39 patients). Patients with retrievable filters had significantly more complications overall than those with permanent filters. Device related complications (vena cava perforation, filter migration and filter fracture) were significantly more common with retrievable filters compared to permanent filters. The authors expressed the view that retrievable filters may have sacrificed long-term design integrity for the sake of ease of retrievability. They warned, “Long term use of retrievable filters should be avoided…” The results of the investigation were published in the Journal of Vascular Surgery: Venous and Lymphatic Disorders™ in 2014.

“With regard to retrievable filters, the design of the filter must be such that it allows the filter to be collapsed during retrieval like an umbrella, allowing it to be withdrawn through a vascular sheath. It is felt that this structural modification, in comparison with permanent filter designs, is the engineering trade-off between long-term design integrity vs ease of retrievability.” - Tina R. Desai, MD, et al., “Complications of indwelling retrievable versus permanent inferior vena cava filters,” Journal of Vascular Surgery: Venous and Lymphatic Disorders, 2014.

Complications Associated With Particular IVC Filter Brands:

Celect IVC Filter and Günther Tulip IVC Filter

Both of these IVC filters have been associated with high rates of perforation of the inferior vena cava by the filter legs. This not only damages the IVC, but can damage organs outside the IVC, including the aorta, intestines, kidneys, pancreas and spinal column.

In one 2012 study of Celect and Günther Tulip filters, CT scans by doctors at the University of California revealed perforation of filter components through the wall of the IVC in 86% of patients. A study by doctors at Northwestern University also revealed significant rates of vena cava penetration associated with Cook’s Celect and Günther Tulip filters. Filter fracture, tilt and migration were also seen in the Cook filters.

Bard Retrievable IVC Filters

The Northwestern University study (mentioned above) investigated six different Bard IVC filters as well as the Cook filters and several other brands. The six Bard filters were the Recovery, G2, G2X, G2 Express, Eclipse and Meridian. Filter fracture and limb embolization (the movement of a fractured filter leg through the IVC to another location, such as the heart or lung) were both higher for the Bard filters than any of the other filters investigated. For more information on complications linked to this filter, visit the Bard IVC Filter page.

Optease IVC Filter

In May 2015, the journal Thrombosis Research published a study of 142 patients who experienced a major trauma (71 were involved in motor vehicle accidents) and were treated with an Optease IVC filter. The formation of blood clots in a vein (known as “venous thromboembolism”) is often seen in trauma patients. The researchers reported that despite the use of anticoagulant medication, 13% of the patients developed blood clots (deep vein thrombosis) and IVC thrombosis (clogging of the filter due to blood clots). The authors suggest that the Optease IVC filter, due to its design, may be a “prothrombotic device”, i.e., it may actually promote the formation of blood clots. Removal of the filter was unsuccessful in 13 patients. The doctors expressed concern over the “persistent complications” related to the use of these devices and stated that their routine use in trauma patients “may not be desirable.”

TrapEase IVC Filter

A Japanese study of Cordis’ permament TrapEase IVC filter found that patients who received this filter were at “extremely high risk of strut fractures” as early as two to three years after placement of the filter.

The PRESERVE IVC Filter Study

Approximately 2,100 subjects are currently being enrolled in a five-year study of IVC filters known as the PRESERVE (Predicting the Safety and Effectiveness of Inferior Vena Cava Filters) study. Filters made by seven different IVC filter manufacturers will be tested and 300 subjects will be enrolled for each filter.

The seven filters to be tested (and their manufacturers) are as follows:

• ALN Vena Cava Filter (ALN Implants Chirurgicaux)
• Option™ Elite Retrievable Vena Cava Filter (Rex Medical)
• VenaTech^® LP Vena Cava Filter (B. Braun)
• Cook Günther Tulip Vena Cava Filter (Cook Incorporated)
• DENALI^® Vena Cava Filter System (C.R. Bard Peripheral Vascular, Inc.)
• OptEase^® Retrievable Vena Cava Filter/ Cordis TrapEase^® Vena Cava Filter (Cordis Corporation)
• Crux^® Vena Cava Filter System (Volcano Corporation)

The study will investigate the major IVC filter complications that have been associated with these medical devices. These include:

• Penetration of filter legs through the inferior vena cava wall resulting in:
  • hemorrhage or hematoma
  • touching or perforation of other organs
  • a decision to remove the filter
• Movement of the filter or its parts to a distant site (e.g., heart, lungs).
• Occlusion (blocking) of the inferior vena cava. This can be caused by the filter capturing blood clots or the tendency of the filter to promote the formation of blood clots.
• Deep vein thrombosis that occurred after the implantation of the filter.
• Other serious adverse events.

The project is being guided by the IVC Filter Study Group Foundation, which is jointly sponsored by the Society for Vascular Surgery (SVS) and the Society of Interventional Radiology (SIR). The filter manufacturers are funding the research and collaborating with New England Research Institutes Inc. (NERI) in carrying out the study.

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