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August 9, 2010

Single-Center Study Analyzes Vena Cava Filter Fractures

August 9, 2010—In Archives of Internal Medicine, a single-center, cross-sectional study reported evidence of inferior vena cava (IVC) filters fracturing inside the body, with some fractured fragments traveling to the heart and causing potentially life-threatening complications. The study was published online and will appear in the November 8, 2010 print issue.
 


According to the Archives of Internal Medicine, after one initial case of a fractured filter, William Nicholson, MD, et al evaluated 189 patients who received IVC filters at their institution, York Hospital in Pennsylvania, between April 2004 and January 2009 to determine the prevalence of fracture and embolization. Of these patients, one was pregnant, 35 had died, and 10 already had their filter removed. A total of 80 patients underwent fluoroscopy to assess the integrity of their filters, and those whose filters were fragmented also underwent echocardiography and cardiac computed tomography.

Patients in the study received either the Bard Recovery (first generation) or the Bard G2 (second generation) vena cava filters (Bard Peripheral Vascular, Inc., Tempe, AZ). Speaking with Endovascular Today, Dr. Nicholson stated that the reason only Bard filters were included in the study was that the vast majority of retrievable filters implanted at the center at the time were those manufactured by Bard.

The Bard Recovery filter was designed to be permanently implanted or retrieved as needed. The Recovery device was commercially available from April 2003 through October 2005. In September 2005, Bard modified the design of the filter to improve its resistance to fracture and introduced the device as the G2 vena cava filter. Bard's most recent version of its filter, the Eclipse, was not involved in the study.

The investigators reported that 13 of 80 patients (16%) had at least one arm or strut fracture in their filter. This included seven of 28 filters (25%) that fractured and embolized among patients with the first-generation filter. In five of these seven cases (71%), at least one fragment traveled to the heart; three of these patients experienced life-threatening symptoms of rapid heartbeat or fluid buildup around the heart, and one experienced sudden death at home.
The investigators noted that although the second-generation filter incorporated engineering modifications to reduce these occurrences, 12% of those implanted filters also fractured (six of 52). In two of these six cases, the fragment blocked blood flow (one in the vein leading from the liver and one in the lungs). In the other four cases, the fragments remained close to the filter. 
 

Commenting to the Associated Press on this study, Bram Zuckerman, MD, director of the FDA's Center for Devices and Radiological Health's Division of Cardiovascular Devices, said that the York Hospital's rate seems high and may not be nationally representative.

In a separate interview with Endovascular Today, FDA experts put this recent study in context. “The York Hospital paper is an important contribution to the literature. However, limitations to this paper must also be recognized so that physicians and the public can understand how to best integrate the York data into the general literature in this field. Despite the higher complication rates reported by Dr. Nicholson, not all of the current literature reports for G2 IVC filter fracture rates are in the > 10% range. For example, four recent manuscripts published in the Journal of Vascular and Interventional Radiology demonstrated fracture rates with the G2 filter between 0% and 3.5%. Additionally, the quality improvement guidelines for percutaneous permanent IVC filter placement from the Society for Interventional Radiology suggested that filter fracture rates are expected to range from 2% to 10%.”

On August 9, 2010, the FDA issued a separate communication regarding vena cava filter fractures. Click here to read Endovascular Today's coverage of that announcement. 

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