CADRIOVASCULAR

John Rectenwald, M.D., M.S., FACS, led the creation of the nation's first IVC filter registry.

Short-term Solution

IVC filters are often not retrieved after their purpose is served

issue 19 | Fall 2013

More inferior vena cava filters, cage-like devices that catch blood clots and prevent them from reaching the lungs, are being implanted in patients than ever before. Some patients will require the long-term protection provided by the filter from potentially deadly pulmonary embolisms, but others only require a short-term safeguard. It is for treatment of the latter group that retrievable filters were developed. They can be removed when the patient no longer needs the protection the filter provides.

John Rectenwald, M.D., M.S., associate professor of surgery and radiology at the University of Michigan Medical School, led the creation of the first prospective national IVC filter registry and offers recommendations about the ongoing care of the thousands of patients implanted with IVC filters each year.

"There's concern that these IVC filters, intended for retrieval, are not always removed once a patient's risk for PE is over," Rectenwald says. "In real-world use, much less than 50 percent of retrievable filters are actually removed as intended."

Known potential complications of IVC filters are recurrent deep vein thrombosis and pulmonary embolism, filter migration, caval perforation, wire entanglement, and device fatigue and fracture.

DATA IS LACKING

"Retrievable filters are designed for retrieval and may be at increased risk for fracture and migration," says Rectenwald, a vascular surgeon at U-M Frankel Cardiovascular Center. "All retrievable filters were first approved for permanent placement, but data on these filters' long-term performance is lacking."

Implanting physicians and clinicians responsible for the ongoing care of patients with IVC filters, including interventional radiologists, interventional cardiologists, vascular surgeons, emergency room physicians, bariatric surgeons, orthopedic surgeons and primary care physicians, are urged to take a second look at their use of IVC filters and avoid the use of prophylactic IVC filters whenever possible. IVC filter use has skyrocketed since 1979 when 2,000 of them were implanted. By 2007, almost 167,000 filters were implanted and the market for filters is only expected to increase. Today an estimated 267,000 IVC filters are deployed annually.

PERMANENT OR RETRIEVABLE?

"Retrievable IVC filters are attractive in the patient with a well-defined, short-term risk for VTE who cannot tolerate anticoagulation," says Rectenwald. "But if the responsible physician does not intend to remove a filter, then I believe a permanent filter should be placed." More than 10 permanent and retrievable IVC filters are on the market in North America, and their use is intuitive, he says. The filters are intended to be used in patients who have deep venous thrombosis or PE and have a contraindication to anticoagulation, or in patients who hemorrhage while anticoagulated for DVT.

He notes that filters are useful for preventing pulmonary embolisms — risk factors include history of DVT, having surgery or certain orthopedic fractures, certain diseases or conditions such as hemorrhagic stroke, profound paralysis, right heart failure or severe pulmonary hypertension — but the devices do not treat the underlying DVT.

"The spirited debate concerning which patient should get which type of filter is just beginning," says the UM vascular surgeon. "More prospective, randomized trials evaluating optional retrievable filters are needed to answer these important questions."